Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Sam- Under the current design, you can provide a specific endpoint (singular) via the `endpoint_override` conf option. Based on feedback on this thread, we will also be keeping support for `[glance]api_servers` for consumers who actually need to be able to specify multiple endpoints. See latest spec proposal[1] for details. [1] https://review.openstack.org/#/c/461481/ Thanks, Eric (efried) On 05/01/2017 12:20 PM, Sam Morrison wrote: > >> On 1 May 2017, at 4:24 pm, Sean McGinniswrote: >> >> On Mon, May 01, 2017 at 10:17:43AM -0400, Matthew Treinish wrote: >>> >>> I thought it was just nova too, but it turns out cinder has the same exact >>> option as nova: (I hit this in my devstack patch trying to get glance >>> deployed >>> as a wsgi app) >>> >>> https://github.com/openstack/cinder/blob/d47eda3a3ba9971330b27beeeb471e2bc94575ca/cinder/common/config.py#L51-L55 >>> >>> Although from what I can tell you don't have to set it and it will fallback >>> to >>> using the catalog, assuming you configured the catalog info for cinder: >>> >>> https://github.com/openstack/cinder/blob/19d07a1f394c905c23f109c1888c019da830b49e/cinder/image/glance.py#L117-L129 >>> >>> >>> -Matt Treinish >>> >> >> FWIW, that came with the original fork out of Nova. I do not have any real >> world data on whether that is used or not. > > Yes this is used in cinder. > > A lot of the projects you can set endpoints for them to use. This is > extremely useful in a a large production Openstack install where you want to > control the traffic. > > I can understand using the catalog in certain situations and feel it’s OK for > that to be the default but please don’t prevent operators configuring it > differently. > > Glance is the big one as you want to control the data flow efficiently but > any service to service configuration should ideally be able to be manually > configured. > > Cheers, > Sam > > >> >> >> __ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > __ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
On 29 April 2017 at 01:46, Mike Dormanwrote: > I don’t disagree with you that the client side choose-a-server-at-random is > not a great load balancer. (But isn’t this roughly the same thing that > oslo-messaging does when we give it a list of RMQ servers?) For us it’s more > about the failure handling if one is down than it is about actually equally > distributing the load. Maybe not great, but still better than making operators deploy (often complex) full-featured external LBs when they really just want *enough* redundancy. In many cases this seems to just create pets in the control plane. I think it'd be useful if all OpenStack APIs and their clients actively handled this poor-man's HA without having to resort to haproxy etc, or e.g., assuming operators own the DNS. -- Cheers, ~Blairo __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
> On 1 May 2017, at 4:24 pm, Sean McGinniswrote: > > On Mon, May 01, 2017 at 10:17:43AM -0400, Matthew Treinish wrote: >>> >> >> I thought it was just nova too, but it turns out cinder has the same exact >> option as nova: (I hit this in my devstack patch trying to get glance >> deployed >> as a wsgi app) >> >> https://github.com/openstack/cinder/blob/d47eda3a3ba9971330b27beeeb471e2bc94575ca/cinder/common/config.py#L51-L55 >> >> Although from what I can tell you don't have to set it and it will fallback >> to >> using the catalog, assuming you configured the catalog info for cinder: >> >> https://github.com/openstack/cinder/blob/19d07a1f394c905c23f109c1888c019da830b49e/cinder/image/glance.py#L117-L129 >> >> >> -Matt Treinish >> > > FWIW, that came with the original fork out of Nova. I do not have any real > world data on whether that is used or not. Yes this is used in cinder. A lot of the projects you can set endpoints for them to use. This is extremely useful in a a large production Openstack install where you want to control the traffic. I can understand using the catalog in certain situations and feel it’s OK for that to be the default but please don’t prevent operators configuring it differently. Glance is the big one as you want to control the data flow efficiently but any service to service configuration should ideally be able to be manually configured. Cheers, Sam > > > __ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Matt- Yeah, clearly other projects have the same issuethis blueprint is trying to solve in nova. I think the idea is that, once the infrastructure is in place and nova has demonstrated the concept, other projects can climbaboard. It's conceivable that the new get_service_url() method could be moved to a more common lib (ksaor os-client-config perhaps) in the future to facilitate this. Eric (efried) On 05/01/2017 09:17 AM, Matthew Treinish wrote: > On Mon, May 01, 2017 at 05:00:17AM -0700, Flavio Percoco wrote: >> On 28/04/17 11:19 -0500, Eric Fried wrote: >>> If it's *just* glance we're making an exception for, I prefer #1 (don't >>> deprecate/remove [glance]api_servers). It's way less code & >>> infrastructure, and it discourages others from jumping on the >>> multiple-endpoints bandwagon. If we provide endpoint_override_list >>> (handwave), people will think it's okay to use it. >>> >>> Anyone aware of any other services that use multiple endpoints? >> Probably a bit late but yeah, I think this makes sense. I'm not aware of >> other >> projects that have list of api_servers. > I thought it was just nova too, but it turns out cinder has the same exact > option as nova: (I hit this in my devstack patch trying to get glance deployed > as a wsgi app) > > https://github.com/openstack/cinder/blob/d47eda3a3ba9971330b27beeeb471e2bc94575ca/cinder/common/config.py#L51-L55 > > Although from what I can tell you don't have to set it and it will fallback to > using the catalog, assuming you configured the catalog info for cinder: > > https://github.com/openstack/cinder/blob/19d07a1f394c905c23f109c1888c019da830b49e/cinder/image/glance.py#L117-L129 > > > -Matt Treinish > > >>> On 04/28/2017 10:46 AM, Mike Dorman wrote: Maybe we are talking about two different things here? I’m a bit confused. Our Glance config in nova.conf on HV’s looks like this: [glance] api_servers=http://glance1:9292,http://glance2:9292,http://glance3:9292,http://glance4:9292 glance_api_insecure=True glance_num_retries=4 glance_protocol=http >> >> FWIW, this feature is being used as intended. I'm sure there are ways to >> achieve >> this using external tools like haproxy/nginx but that adds an extra burden to >> OPs that is probably not necessary since this functionality is already there. >> >> Flavio >> So we do provide the full URLs, and there is SSL support. Right? I am fairly certain we tested this to ensure that if one URL fails, nova goes on to retry the next one. That failure does not get bubbled up to the user (which is ultimately the goal.) I don’t disagree with you that the client side choose-a-server-at-random is not a great load balancer. (But isn’t this roughly the same thing that oslo-messaging does when we give it a list of RMQ servers?) For us it’s more about the failure handling if one is down than it is about actually equally distributing the load. In my mind options One and Two are the same, since today we are already providing full URLs and not only server names. At the end of the day, I don’t feel like there is a compelling argument here to remove this functionality (that people are actively making use of.) To be clear, I, and I think others, are fine with nova by default getting the Glance endpoint from Keystone. And that in Keystone there should exist only one Glance endpoint. What I’d like to see remain is the ability to override that for nova-compute and to target more than one Glance URL for purposes of fail over. Thanks, Mike On 4/28/17, 8:20 AM, "Monty Taylor"wrote: Thank you both for your feedback - that's really helpful. Let me say a few more words about what we're trying to accomplish here overall so that maybe we can figure out what the right way forward is. (it may be keeping the glance api servers setting, but let me at least make the case real quick) From a 10,000 foot view, the thing we're trying to do is to get nova's consumption of all of the OpenStack services it uses to be less special. The clouds have catalogs which list information about the services - public, admin and internal endpoints and whatnot - and then we're asking admins to not only register that information with the catalog, but to also put it into the nova.conf. That means that any updating of that info needs to be an API call to keystone and also a change to nova.conf. If we, on the other hand, use the catalog, then nova can pick up changes in real time as they're rolled out to the cloud - and there is hopefully a sane set of defaults we could choose (based on operator feedback like what
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
On Mon, May 01, 2017 at 10:17:43AM -0400, Matthew Treinish wrote: > > > > I thought it was just nova too, but it turns out cinder has the same exact > option as nova: (I hit this in my devstack patch trying to get glance deployed > as a wsgi app) > > https://github.com/openstack/cinder/blob/d47eda3a3ba9971330b27beeeb471e2bc94575ca/cinder/common/config.py#L51-L55 > > Although from what I can tell you don't have to set it and it will fallback to > using the catalog, assuming you configured the catalog info for cinder: > > https://github.com/openstack/cinder/blob/19d07a1f394c905c23f109c1888c019da830b49e/cinder/image/glance.py#L117-L129 > > > -Matt Treinish > FWIW, that came with the original fork out of Nova. I do not have any real world data on whether that is used or not. __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
On Mon, May 01, 2017 at 05:00:17AM -0700, Flavio Percoco wrote: > On 28/04/17 11:19 -0500, Eric Fried wrote: > > If it's *just* glance we're making an exception for, I prefer #1 (don't > > deprecate/remove [glance]api_servers). It's way less code & > > infrastructure, and it discourages others from jumping on the > > multiple-endpoints bandwagon. If we provide endpoint_override_list > > (handwave), people will think it's okay to use it. > > > > Anyone aware of any other services that use multiple endpoints? > > Probably a bit late but yeah, I think this makes sense. I'm not aware of other > projects that have list of api_servers. I thought it was just nova too, but it turns out cinder has the same exact option as nova: (I hit this in my devstack patch trying to get glance deployed as a wsgi app) https://github.com/openstack/cinder/blob/d47eda3a3ba9971330b27beeeb471e2bc94575ca/cinder/common/config.py#L51-L55 Although from what I can tell you don't have to set it and it will fallback to using the catalog, assuming you configured the catalog info for cinder: https://github.com/openstack/cinder/blob/19d07a1f394c905c23f109c1888c019da830b49e/cinder/image/glance.py#L117-L129 -Matt Treinish > > > On 04/28/2017 10:46 AM, Mike Dorman wrote: > > > Maybe we are talking about two different things here? I’m a bit confused. > > > > > > Our Glance config in nova.conf on HV’s looks like this: > > > > > > [glance] > > > api_servers=http://glance1:9292,http://glance2:9292,http://glance3:9292,http://glance4:9292 > > > glance_api_insecure=True > > > glance_num_retries=4 > > > glance_protocol=http > > > FWIW, this feature is being used as intended. I'm sure there are ways to > achieve > this using external tools like haproxy/nginx but that adds an extra burden to > OPs that is probably not necessary since this functionality is already there. > > Flavio > > > > So we do provide the full URLs, and there is SSL support. Right? I am > > > fairly certain we tested this to ensure that if one URL fails, nova goes > > > on to retry the next one. That failure does not get bubbled up to the > > > user (which is ultimately the goal.) > > > > > > I don’t disagree with you that the client side choose-a-server-at-random > > > is not a great load balancer. (But isn’t this roughly the same thing > > > that oslo-messaging does when we give it a list of RMQ servers?) For us > > > it’s more about the failure handling if one is down than it is about > > > actually equally distributing the load. > > > > > > In my mind options One and Two are the same, since today we are already > > > providing full URLs and not only server names. At the end of the day, I > > > don’t feel like there is a compelling argument here to remove this > > > functionality (that people are actively making use of.) > > > > > > To be clear, I, and I think others, are fine with nova by default getting > > > the Glance endpoint from Keystone. And that in Keystone there should > > > exist only one Glance endpoint. What I’d like to see remain is the > > > ability to override that for nova-compute and to target more than one > > > Glance URL for purposes of fail over. > > > > > > Thanks, > > > Mike > > > > > > > > > > > > > > > On 4/28/17, 8:20 AM, "Monty Taylor"wrote: > > > > > > Thank you both for your feedback - that's really helpful. > > > > > > Let me say a few more words about what we're trying to accomplish here > > > overall so that maybe we can figure out what the right way forward is. > > > (it may be keeping the glance api servers setting, but let me at least > > > make the case real quick) > > > > > > From a 10,000 foot view, the thing we're trying to do is to get > > > nova's > > > consumption of all of the OpenStack services it uses to be less > > > special. > > > > > > The clouds have catalogs which list information about the services - > > > public, admin and internal endpoints and whatnot - and then we're > > > asking > > > admins to not only register that information with the catalog, but to > > > also put it into the nova.conf. That means that any updating of that > > > info needs to be an API call to keystone and also a change to > > > nova.conf. > > > If we, on the other hand, use the catalog, then nova can pick up > > > changes > > > in real time as they're rolled out to the cloud - and there is > > > hopefully > > > a sane set of defaults we could choose (based on operator feedback > > > like > > > what you've given) so that in most cases you don't have to tell nova > > > where to find glance _at_all_ becuase the cloud already knows where it > > > is. (nova would know to look in the catalog for the interal interface > > > of > > > the image service - for instance - there's no need to ask an operator > > > to > > > add to the config "what is the service_type of the image service we > > >
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
On 28/04/17 11:19 -0500, Eric Fried wrote: If it's *just* glance we're making an exception for, I prefer #1 (don't deprecate/remove [glance]api_servers). It's way less code & infrastructure, and it discourages others from jumping on the multiple-endpoints bandwagon. If we provide endpoint_override_list (handwave), people will think it's okay to use it. Anyone aware of any other services that use multiple endpoints? Probably a bit late but yeah, I think this makes sense. I'm not aware of other projects that have list of api_servers. On 04/28/2017 10:46 AM, Mike Dorman wrote: Maybe we are talking about two different things here? I’m a bit confused. Our Glance config in nova.conf on HV’s looks like this: [glance] api_servers=http://glance1:9292,http://glance2:9292,http://glance3:9292,http://glance4:9292 glance_api_insecure=True glance_num_retries=4 glance_protocol=http FWIW, this feature is being used as intended. I'm sure there are ways to achieve this using external tools like haproxy/nginx but that adds an extra burden to OPs that is probably not necessary since this functionality is already there. Flavio So we do provide the full URLs, and there is SSL support. Right? I am fairly certain we tested this to ensure that if one URL fails, nova goes on to retry the next one. That failure does not get bubbled up to the user (which is ultimately the goal.) I don’t disagree with you that the client side choose-a-server-at-random is not a great load balancer. (But isn’t this roughly the same thing that oslo-messaging does when we give it a list of RMQ servers?) For us it’s more about the failure handling if one is down than it is about actually equally distributing the load. In my mind options One and Two are the same, since today we are already providing full URLs and not only server names. At the end of the day, I don’t feel like there is a compelling argument here to remove this functionality (that people are actively making use of.) To be clear, I, and I think others, are fine with nova by default getting the Glance endpoint from Keystone. And that in Keystone there should exist only one Glance endpoint. What I’d like to see remain is the ability to override that for nova-compute and to target more than one Glance URL for purposes of fail over. Thanks, Mike On 4/28/17, 8:20 AM, "Monty Taylor"wrote: Thank you both for your feedback - that's really helpful. Let me say a few more words about what we're trying to accomplish here overall so that maybe we can figure out what the right way forward is. (it may be keeping the glance api servers setting, but let me at least make the case real quick) From a 10,000 foot view, the thing we're trying to do is to get nova's consumption of all of the OpenStack services it uses to be less special. The clouds have catalogs which list information about the services - public, admin and internal endpoints and whatnot - and then we're asking admins to not only register that information with the catalog, but to also put it into the nova.conf. That means that any updating of that info needs to be an API call to keystone and also a change to nova.conf. If we, on the other hand, use the catalog, then nova can pick up changes in real time as they're rolled out to the cloud - and there is hopefully a sane set of defaults we could choose (based on operator feedback like what you've given) so that in most cases you don't have to tell nova where to find glance _at_all_ becuase the cloud already knows where it is. (nova would know to look in the catalog for the interal interface of the image service - for instance - there's no need to ask an operator to add to the config "what is the service_type of the image service we should talk to" :) ) Now - glance, and the thing you like that we don't - is especially hairy because of the api_servers list. The list, as you know, is just a list of servers, not even of URLs. This means it's not possible to configure nova to talk to glance over SSL (which I know you said works for you, but we'd like for people to be able to choose to SSL all their things) We could add that, but it would be an additional pile of special config. Because of all of that, we also have to attempt to make working URLs from what is usually a list of IP addresses. This is also clunky and prone to failure. The implementation on the underside of the api_servers code is the world's dumbest load balancer. It picks a server from the list at random and uses it. There is no facility for dealing with a server in the list that stops working or for allowing rolling upgrades like there would with a real load-balancer across the set. If one of the API servers goes away, we have no context to know that, so just some of your internal calls to glance fail. Those
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
See - this is what happens when I write an entirely too long email while on coffee number one. :) Yes - you are, obviously, entirely right. I had clearly blocked memory of those pieces out of my memory. I still blame the coffee. It's down to the round-robin impl. Thanks for keeping me honest. On 04/28/2017 10:46 AM, Mike Dorman wrote: Maybe we are talking about two different things here? I’m a bit confused. Our Glance config in nova.conf on HV’s looks like this: [glance] api_servers=http://glance1:9292,http://glance2:9292,http://glance3:9292,http://glance4:9292 glance_api_insecure=True glance_num_retries=4 glance_protocol=http So we do provide the full URLs, and there is SSL support. Right? I am fairly certain we tested this to ensure that if one URL fails, nova goes on to retry the next one. That failure does not get bubbled up to the user (which is ultimately the goal.) I don’t disagree with you that the client side choose-a-server-at-random is not a great load balancer. (But isn’t this roughly the same thing that oslo-messaging does when we give it a list of RMQ servers?) For us it’s more about the failure handling if one is down than it is about actually equally distributing the load. In my mind options One and Two are the same, since today we are already providing full URLs and not only server names. At the end of the day, I don’t feel like there is a compelling argument here to remove this functionality (that people are actively making use of.) To be clear, I, and I think others, are fine with nova by default getting the Glance endpoint from Keystone. And that in Keystone there should exist only one Glance endpoint. What I’d like to see remain is the ability to override that for nova-compute and to target more than one Glance URL for purposes of fail over. Thanks, Mike On 4/28/17, 8:20 AM, "Monty Taylor"wrote: Thank you both for your feedback - that's really helpful. Let me say a few more words about what we're trying to accomplish here overall so that maybe we can figure out what the right way forward is. (it may be keeping the glance api servers setting, but let me at least make the case real quick) From a 10,000 foot view, the thing we're trying to do is to get nova's consumption of all of the OpenStack services it uses to be less special. The clouds have catalogs which list information about the services - public, admin and internal endpoints and whatnot - and then we're asking admins to not only register that information with the catalog, but to also put it into the nova.conf. That means that any updating of that info needs to be an API call to keystone and also a change to nova.conf. If we, on the other hand, use the catalog, then nova can pick up changes in real time as they're rolled out to the cloud - and there is hopefully a sane set of defaults we could choose (based on operator feedback like what you've given) so that in most cases you don't have to tell nova where to find glance _at_all_ becuase the cloud already knows where it is. (nova would know to look in the catalog for the interal interface of the image service - for instance - there's no need to ask an operator to add to the config "what is the service_type of the image service we should talk to" :) ) Now - glance, and the thing you like that we don't - is especially hairy because of the api_servers list. The list, as you know, is just a list of servers, not even of URLs. This means it's not possible to configure nova to talk to glance over SSL (which I know you said works for you, but we'd like for people to be able to choose to SSL all their things) We could add that, but it would be an additional pile of special config. Because of all of that, we also have to attempt to make working URLs from what is usually a list of IP addresses. This is also clunky and prone to failure. The implementation on the underside of the api_servers code is the world's dumbest load balancer. It picks a server from the list at random and uses it. There is no facility for dealing with a server in the list that stops working or for allowing rolling upgrades like there would with a real load-balancer across the set. If one of the API servers goes away, we have no context to know that, so just some of your internal calls to glance fail. Those are the issues - basically: - current config is special and fragile - impossible to SSL - unflexible/unpowerful de-facto software loadbalancer Now - as is often the case - it turns out the combo of those things is working very well for you -so we need to adjust our thinking on the topic a bit. Let me toss out some alternatives and see what you think: Alternative One - Do Both things We add the new "consume from catalog" and make it default. (and make it
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
If it's *just* glance we're making an exception for, I prefer #1 (don't deprecate/remove [glance]api_servers). It's way less code & infrastructure, and it discourages others from jumping on the multiple-endpoints bandwagon. If we provide endpoint_override_list (handwave), people will think it's okay to use it. Anyone aware of any other services that use multiple endpoints? On 04/28/2017 10:46 AM, Mike Dorman wrote: > Maybe we are talking about two different things here? I’m a bit confused. > > Our Glance config in nova.conf on HV’s looks like this: > > [glance] > api_servers=http://glance1:9292,http://glance2:9292,http://glance3:9292,http://glance4:9292 > glance_api_insecure=True > glance_num_retries=4 > glance_protocol=http > > So we do provide the full URLs, and there is SSL support. Right? I am > fairly certain we tested this to ensure that if one URL fails, nova goes on > to retry the next one. That failure does not get bubbled up to the user > (which is ultimately the goal.) > > I don’t disagree with you that the client side choose-a-server-at-random is > not a great load balancer. (But isn’t this roughly the same thing that > oslo-messaging does when we give it a list of RMQ servers?) For us it’s more > about the failure handling if one is down than it is about actually equally > distributing the load. > > In my mind options One and Two are the same, since today we are already > providing full URLs and not only server names. At the end of the day, I > don’t feel like there is a compelling argument here to remove this > functionality (that people are actively making use of.) > > To be clear, I, and I think others, are fine with nova by default getting the > Glance endpoint from Keystone. And that in Keystone there should exist only > one Glance endpoint. What I’d like to see remain is the ability to override > that for nova-compute and to target more than one Glance URL for purposes of > fail over. > > Thanks, > Mike > > > > > On 4/28/17, 8:20 AM, "Monty Taylor"wrote: > > Thank you both for your feedback - that's really helpful. > > Let me say a few more words about what we're trying to accomplish here > overall so that maybe we can figure out what the right way forward is. > (it may be keeping the glance api servers setting, but let me at least > make the case real quick) > > From a 10,000 foot view, the thing we're trying to do is to get nova's > consumption of all of the OpenStack services it uses to be less special. > > The clouds have catalogs which list information about the services - > public, admin and internal endpoints and whatnot - and then we're asking > admins to not only register that information with the catalog, but to > also put it into the nova.conf. That means that any updating of that > info needs to be an API call to keystone and also a change to nova.conf. > If we, on the other hand, use the catalog, then nova can pick up changes > in real time as they're rolled out to the cloud - and there is hopefully > a sane set of defaults we could choose (based on operator feedback like > what you've given) so that in most cases you don't have to tell nova > where to find glance _at_all_ becuase the cloud already knows where it > is. (nova would know to look in the catalog for the interal interface of > the image service - for instance - there's no need to ask an operator to > add to the config "what is the service_type of the image service we > should talk to" :) ) > > Now - glance, and the thing you like that we don't - is especially hairy > because of the api_servers list. The list, as you know, is just a list > of servers, not even of URLs. This means it's not possible to configure > nova to talk to glance over SSL (which I know you said works for you, > but we'd like for people to be able to choose to SSL all their things) > We could add that, but it would be an additional pile of special config. > Because of all of that, we also have to attempt to make working URLs > from what is usually a list of IP addresses. This is also clunky and > prone to failure. > > The implementation on the underside of the api_servers code is the > world's dumbest load balancer. It picks a server from the list at > random and uses it. There is no facility for dealing with a server in > the list that stops working or for allowing rolling upgrades like there > would with a real load-balancer across the set. If one of the API > servers goes away, we have no context to know that, so just some of your > internal calls to glance fail. > > Those are the issues - basically: > - current config is special and fragile > - impossible to SSL > - unflexible/unpowerful de-facto software loadbalancer > > Now - as is often the
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Well, endpoint_overrride itself is already a concept with keystoneauth and all of the various client libraries (and more generally is already a concept in consuming the API services) It's a singleton - so we'd need to add a concept of an endpoint_override_list (*handwave on name*) Oh - oops - I just now noticed that this was a reply to Eric and not to my ludicrously unreadable long novel of an email. :) I'll go back to my hole ... On 04/28/2017 09:25 AM, Mike Dorman wrote: Ok. That would solve some of the problem for us, but we’d still be losing the redundancy. We could do some HAProxy tricks to route around downed services, but it wouldn’t handle the case when that one physical box is down. Is there some downside to allowing endpoint_override to remain a list? That piece seems orthogonal to the spec and IRC discussion referenced, which are more around the service catalog. I don’t think anyone in this thread is arguing against the idea that there should be just one endpoint URL in the catalog. But it seems like there are good reasons to allow multiples on the override setting (at least for glance in nova-compute.) Thanks, Mike On 4/28/17, 8:05 AM, "Eric Fried"wrote: Blair, Mike- There will be an endpoint_override that will bypass the service catalog. It still only takes one URL, though. Thanks, Eric (efried) On 04/27/2017 11:50 PM, Blair Bethwaite wrote: > We at Nectar are in the same boat as Mike. Our use-case is a little > bit more about geo-distributed operations though - our Cells are in > different States around the country, so the local glance-apis are > particularly important for caching popular images close to the > nova-computes. We consider these glance-apis as part of the underlying > cloud infra rather than user-facing, so I think we'd prefer not to see > them in the service-catalog returned to users either... is there going > to be a (standard) way to hide them? > > On 28 April 2017 at 09:15, Mike Dorman wrote: >> We make extensive use of the [glance]/api_servers list. We configure that on hypervisors to direct them to Glance servers which are more “local” network-wise (in order to reduce network traffic across security zones/firewalls/etc.) This way nova-compute can fail over in case one of the Glance servers in the list is down, without putting them behind a load balancer. We also don’t run https for these “internal” Glance calls, to save the overhead when transferring images. >> >> End-user calls to Glance DO go through a real load balancer and then are distributed out to the Glance servers on the backend. From the end-user’s perspective, I totally agree there should be one, and only one URL. >> >> However, we would be disappointed to see the change you’re suggesting implemented. We would lose the redundancy we get now by providing a list. Or we would have to shunt all the calls through the user-facing endpoint, which would generate a lot of extra traffic (in places where we don’t want it) for image transfers. >> >> Thanks, >> Mike >> >> >> >> On 4/27/17, 4:02 PM, "Matt Riedemann" wrote: >> >> On 4/27/2017 4:52 PM, Eric Fried wrote: >> > Y'all- >> > >> > TL;DR: Does glance ever really need/use multiple endpoint URLs? >> > >> > I'm working on bp use-service-catalog-for-endpoints[1], which intends >> > to deprecate disparate conf options in various groups, and centralize >> > acquisition of service endpoint URLs. The idea is to introduce >> > nova.utils.get_service_url(group) -- note singular 'url'. >> > >> > One affected conf option is [glance]api_servers[2], which currently >> > accepts a *list* of endpoint URLs. The new API will only ever return *one*. >> > >> > Thus, as planned, this blueprint will have the side effect of >> > deprecating support for multiple glance endpoint URLs in Pike, and >> > removing said support in Queens. >> > >> > Some have asserted that there should only ever be one endpoint URL for >> > a given service_type/interface combo[3]. I'm fine with that - it >> > simplifies things quite a bit for the bp impl - but wanted to make sure >> > there were no loudly-dissenting opinions before we get too far down this >> > path. >> > >> > [1] >> > https://blueprints.launchpad.net/nova/+spec/use-service-catalog-for-endpoints >> > [2] >> > https://github.com/openstack/nova/blob/7e7bdb198ed6412273e22dea72e37a6371fce8bd/nova/conf/glance.py#L27-L37 >> > [3] >> >
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Maybe we are talking about two different things here? I’m a bit confused. Our Glance config in nova.conf on HV’s looks like this: [glance] api_servers=http://glance1:9292,http://glance2:9292,http://glance3:9292,http://glance4:9292 glance_api_insecure=True glance_num_retries=4 glance_protocol=http So we do provide the full URLs, and there is SSL support. Right? I am fairly certain we tested this to ensure that if one URL fails, nova goes on to retry the next one. That failure does not get bubbled up to the user (which is ultimately the goal.) I don’t disagree with you that the client side choose-a-server-at-random is not a great load balancer. (But isn’t this roughly the same thing that oslo-messaging does when we give it a list of RMQ servers?) For us it’s more about the failure handling if one is down than it is about actually equally distributing the load. In my mind options One and Two are the same, since today we are already providing full URLs and not only server names. At the end of the day, I don’t feel like there is a compelling argument here to remove this functionality (that people are actively making use of.) To be clear, I, and I think others, are fine with nova by default getting the Glance endpoint from Keystone. And that in Keystone there should exist only one Glance endpoint. What I’d like to see remain is the ability to override that for nova-compute and to target more than one Glance URL for purposes of fail over. Thanks, Mike On 4/28/17, 8:20 AM, "Monty Taylor"wrote: Thank you both for your feedback - that's really helpful. Let me say a few more words about what we're trying to accomplish here overall so that maybe we can figure out what the right way forward is. (it may be keeping the glance api servers setting, but let me at least make the case real quick) From a 10,000 foot view, the thing we're trying to do is to get nova's consumption of all of the OpenStack services it uses to be less special. The clouds have catalogs which list information about the services - public, admin and internal endpoints and whatnot - and then we're asking admins to not only register that information with the catalog, but to also put it into the nova.conf. That means that any updating of that info needs to be an API call to keystone and also a change to nova.conf. If we, on the other hand, use the catalog, then nova can pick up changes in real time as they're rolled out to the cloud - and there is hopefully a sane set of defaults we could choose (based on operator feedback like what you've given) so that in most cases you don't have to tell nova where to find glance _at_all_ becuase the cloud already knows where it is. (nova would know to look in the catalog for the interal interface of the image service - for instance - there's no need to ask an operator to add to the config "what is the service_type of the image service we should talk to" :) ) Now - glance, and the thing you like that we don't - is especially hairy because of the api_servers list. The list, as you know, is just a list of servers, not even of URLs. This means it's not possible to configure nova to talk to glance over SSL (which I know you said works for you, but we'd like for people to be able to choose to SSL all their things) We could add that, but it would be an additional pile of special config. Because of all of that, we also have to attempt to make working URLs from what is usually a list of IP addresses. This is also clunky and prone to failure. The implementation on the underside of the api_servers code is the world's dumbest load balancer. It picks a server from the list at random and uses it. There is no facility for dealing with a server in the list that stops working or for allowing rolling upgrades like there would with a real load-balancer across the set. If one of the API servers goes away, we have no context to know that, so just some of your internal calls to glance fail. Those are the issues - basically: - current config is special and fragile - impossible to SSL - unflexible/unpowerful de-facto software loadbalancer Now - as is often the case - it turns out the combo of those things is working very well for you -so we need to adjust our thinking on the topic a bit. Let me toss out some alternatives and see what you think: Alternative One - Do Both things We add the new "consume from catalog" and make it default. (and make it default to consuming the internal interface by default) We have to do that in parallel with the current glance api_servers setting anyway, because of deprecation periods, so the code to support both approaches will exist. Instead of then deprecating the
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Ok. That would solve some of the problem for us, but we’d still be losing the redundancy. We could do some HAProxy tricks to route around downed services, but it wouldn’t handle the case when that one physical box is down. Is there some downside to allowing endpoint_override to remain a list? That piece seems orthogonal to the spec and IRC discussion referenced, which are more around the service catalog. I don’t think anyone in this thread is arguing against the idea that there should be just one endpoint URL in the catalog. But it seems like there are good reasons to allow multiples on the override setting (at least for glance in nova-compute.) Thanks, Mike On 4/28/17, 8:05 AM, "Eric Fried"wrote: Blair, Mike- There will be an endpoint_override that will bypass the service catalog. It still only takes one URL, though. Thanks, Eric (efried) On 04/27/2017 11:50 PM, Blair Bethwaite wrote: > We at Nectar are in the same boat as Mike. Our use-case is a little > bit more about geo-distributed operations though - our Cells are in > different States around the country, so the local glance-apis are > particularly important for caching popular images close to the > nova-computes. We consider these glance-apis as part of the underlying > cloud infra rather than user-facing, so I think we'd prefer not to see > them in the service-catalog returned to users either... is there going > to be a (standard) way to hide them? > > On 28 April 2017 at 09:15, Mike Dorman wrote: >> We make extensive use of the [glance]/api_servers list. We configure that on hypervisors to direct them to Glance servers which are more “local” network-wise (in order to reduce network traffic across security zones/firewalls/etc.) This way nova-compute can fail over in case one of the Glance servers in the list is down, without putting them behind a load balancer. We also don’t run https for these “internal” Glance calls, to save the overhead when transferring images. >> >> End-user calls to Glance DO go through a real load balancer and then are distributed out to the Glance servers on the backend. From the end-user’s perspective, I totally agree there should be one, and only one URL. >> >> However, we would be disappointed to see the change you’re suggesting implemented. We would lose the redundancy we get now by providing a list. Or we would have to shunt all the calls through the user-facing endpoint, which would generate a lot of extra traffic (in places where we don’t want it) for image transfers. >> >> Thanks, >> Mike >> >> >> >> On 4/27/17, 4:02 PM, "Matt Riedemann" wrote: >> >> On 4/27/2017 4:52 PM, Eric Fried wrote: >> > Y'all- >> > >> > TL;DR: Does glance ever really need/use multiple endpoint URLs? >> > >> > I'm working on bp use-service-catalog-for-endpoints[1], which intends >> > to deprecate disparate conf options in various groups, and centralize >> > acquisition of service endpoint URLs. The idea is to introduce >> > nova.utils.get_service_url(group) -- note singular 'url'. >> > >> > One affected conf option is [glance]api_servers[2], which currently >> > accepts a *list* of endpoint URLs. The new API will only ever return *one*. >> > >> > Thus, as planned, this blueprint will have the side effect of >> > deprecating support for multiple glance endpoint URLs in Pike, and >> > removing said support in Queens. >> > >> > Some have asserted that there should only ever be one endpoint URL for >> > a given service_type/interface combo[3]. I'm fine with that - it >> > simplifies things quite a bit for the bp impl - but wanted to make sure >> > there were no loudly-dissenting opinions before we get too far down this >> > path. >> > >> > [1] >> > https://blueprints.launchpad.net/nova/+spec/use-service-catalog-for-endpoints >> > [2] >> > https://github.com/openstack/nova/blob/7e7bdb198ed6412273e22dea72e37a6371fce8bd/nova/conf/glance.py#L27-L37 >> > [3] >> > http://eavesdrop.openstack.org/irclogs/%23openstack-keystone/%23openstack-keystone.2017-04-27.log.html#t2017-04-27T20:38:29 >> > >> > Thanks, >> > Eric Fried (efried) >> > . >> > >> > __ >> > OpenStack Development Mailing List (not for usage questions) >> > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> > >>
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Thank you both for your feedback - that's really helpful. Let me say a few more words about what we're trying to accomplish here overall so that maybe we can figure out what the right way forward is. (it may be keeping the glance api servers setting, but let me at least make the case real quick) From a 10,000 foot view, the thing we're trying to do is to get nova's consumption of all of the OpenStack services it uses to be less special. The clouds have catalogs which list information about the services - public, admin and internal endpoints and whatnot - and then we're asking admins to not only register that information with the catalog, but to also put it into the nova.conf. That means that any updating of that info needs to be an API call to keystone and also a change to nova.conf. If we, on the other hand, use the catalog, then nova can pick up changes in real time as they're rolled out to the cloud - and there is hopefully a sane set of defaults we could choose (based on operator feedback like what you've given) so that in most cases you don't have to tell nova where to find glance _at_all_ becuase the cloud already knows where it is. (nova would know to look in the catalog for the interal interface of the image service - for instance - there's no need to ask an operator to add to the config "what is the service_type of the image service we should talk to" :) ) Now - glance, and the thing you like that we don't - is especially hairy because of the api_servers list. The list, as you know, is just a list of servers, not even of URLs. This means it's not possible to configure nova to talk to glance over SSL (which I know you said works for you, but we'd like for people to be able to choose to SSL all their things) We could add that, but it would be an additional pile of special config. Because of all of that, we also have to attempt to make working URLs from what is usually a list of IP addresses. This is also clunky and prone to failure. The implementation on the underside of the api_servers code is the world's dumbest load balancer. It picks a server from the list at random and uses it. There is no facility for dealing with a server in the list that stops working or for allowing rolling upgrades like there would with a real load-balancer across the set. If one of the API servers goes away, we have no context to know that, so just some of your internal calls to glance fail. Those are the issues - basically: - current config is special and fragile - impossible to SSL - unflexible/unpowerful de-facto software loadbalancer Now - as is often the case - it turns out the combo of those things is working very well for you -so we need to adjust our thinking on the topic a bit. Let me toss out some alternatives and see what you think: Alternative One - Do Both things We add the new "consume from catalog" and make it default. (and make it default to consuming the internal interface by default) We have to do that in parallel with the current glance api_servers setting anyway, because of deprecation periods, so the code to support both approaches will exist. Instead of then deprecating the api_servers list, we keep it- but add a big doc warning listing the gotchas and limitations - but for those folks for whom they are not an issue, you've got an out. Alternative Two - Hybrid Approach - optional list of URLs We go ahead and move to service config being the standard way one lists how to consume a service from the catalog. One of the standard options for consuming services is "endpoint_override" - which is a way an API user can say "hi, please to ignore the catalog and use this endpoint I've given you instead". The endpoint in question is a full URL, so https/http and ports and whatnot are all handled properly. We add, in addition, an additional option "endpoint_override_list" which allows you to provide a list of URLs (not API servers) and if you provide that option, we'll keep the logic of choosing one at random at API call time. It's still a poor load balancer, and we'll still put warnings in the docs about it not being a featureful load balancing solution, but again would be available if needed. Alternative Three - We ignore you and give you docs I'm only including this because in the name of completeness. But we could write a bunch of docs about a recommended way of putting your internal endpoints in a load balancer and registering that with the internal endpoint in keystone. (I would prefer to make the operators happy, so let's say whatever vote I have is not for this option) Alternative Four - We update client libs to understand multiple values from keystone for endpoints I _really_ don't like this one - as I think us doing dumb software loadbalancing client side is prone to a ton of failures. BUT - right now the assumption when consuming endpoints from the catalog is that one and only one endpoint will be returned for a
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
Blair, Mike- There will be an endpoint_override that will bypass the service catalog. It still only takes one URL, though. Thanks, Eric (efried) On 04/27/2017 11:50 PM, Blair Bethwaite wrote: > We at Nectar are in the same boat as Mike. Our use-case is a little > bit more about geo-distributed operations though - our Cells are in > different States around the country, so the local glance-apis are > particularly important for caching popular images close to the > nova-computes. We consider these glance-apis as part of the underlying > cloud infra rather than user-facing, so I think we'd prefer not to see > them in the service-catalog returned to users either... is there going > to be a (standard) way to hide them? > > On 28 April 2017 at 09:15, Mike Dormanwrote: >> We make extensive use of the [glance]/api_servers list. We configure that >> on hypervisors to direct them to Glance servers which are more “local” >> network-wise (in order to reduce network traffic across security >> zones/firewalls/etc.) This way nova-compute can fail over in case one of >> the Glance servers in the list is down, without putting them behind a load >> balancer. We also don’t run https for these “internal” Glance calls, to >> save the overhead when transferring images. >> >> End-user calls to Glance DO go through a real load balancer and then are >> distributed out to the Glance servers on the backend. From the end-user’s >> perspective, I totally agree there should be one, and only one URL. >> >> However, we would be disappointed to see the change you’re suggesting >> implemented. We would lose the redundancy we get now by providing a list. >> Or we would have to shunt all the calls through the user-facing endpoint, >> which would generate a lot of extra traffic (in places where we don’t want >> it) for image transfers. >> >> Thanks, >> Mike >> >> >> >> On 4/27/17, 4:02 PM, "Matt Riedemann" wrote: >> >> On 4/27/2017 4:52 PM, Eric Fried wrote: >> > Y'all- >> > >> > TL;DR: Does glance ever really need/use multiple endpoint URLs? >> > >> > I'm working on bp use-service-catalog-for-endpoints[1], which intends >> > to deprecate disparate conf options in various groups, and centralize >> > acquisition of service endpoint URLs. The idea is to introduce >> > nova.utils.get_service_url(group) -- note singular 'url'. >> > >> > One affected conf option is [glance]api_servers[2], which currently >> > accepts a *list* of endpoint URLs. The new API will only ever return >> *one*. >> > >> > Thus, as planned, this blueprint will have the side effect of >> > deprecating support for multiple glance endpoint URLs in Pike, and >> > removing said support in Queens. >> > >> > Some have asserted that there should only ever be one endpoint URL >> for >> > a given service_type/interface combo[3]. I'm fine with that - it >> > simplifies things quite a bit for the bp impl - but wanted to make sure >> > there were no loudly-dissenting opinions before we get too far down >> this >> > path. >> > >> > [1] >> > >> https://blueprints.launchpad.net/nova/+spec/use-service-catalog-for-endpoints >> > [2] >> > >> https://github.com/openstack/nova/blob/7e7bdb198ed6412273e22dea72e37a6371fce8bd/nova/conf/glance.py#L27-L37 >> > [3] >> > >> http://eavesdrop.openstack.org/irclogs/%23openstack-keystone/%23openstack-keystone.2017-04-27.log.html#t2017-04-27T20:38:29 >> > >> > Thanks, >> > Eric Fried (efried) >> > . >> > >> > >> __ >> > OpenStack Development Mailing List (not for usage questions) >> > Unsubscribe: >> openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> > >> >> +openstack-operators >> >> -- >> >> Thanks, >> >> Matt >> >> >> __ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: >> openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> >> ___ >> OpenStack-operators mailing list >> openstack-operat...@lists.openstack.org >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators > > > __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [Openstack-operators] [nova][glance] Who needs multiple api_servers?
We at Nectar are in the same boat as Mike. Our use-case is a little bit more about geo-distributed operations though - our Cells are in different States around the country, so the local glance-apis are particularly important for caching popular images close to the nova-computes. We consider these glance-apis as part of the underlying cloud infra rather than user-facing, so I think we'd prefer not to see them in the service-catalog returned to users either... is there going to be a (standard) way to hide them? On 28 April 2017 at 09:15, Mike Dormanwrote: > We make extensive use of the [glance]/api_servers list. We configure that on > hypervisors to direct them to Glance servers which are more “local” > network-wise (in order to reduce network traffic across security > zones/firewalls/etc.) This way nova-compute can fail over in case one of the > Glance servers in the list is down, without putting them behind a load > balancer. We also don’t run https for these “internal” Glance calls, to save > the overhead when transferring images. > > End-user calls to Glance DO go through a real load balancer and then are > distributed out to the Glance servers on the backend. From the end-user’s > perspective, I totally agree there should be one, and only one URL. > > However, we would be disappointed to see the change you’re suggesting > implemented. We would lose the redundancy we get now by providing a list. > Or we would have to shunt all the calls through the user-facing endpoint, > which would generate a lot of extra traffic (in places where we don’t want > it) for image transfers. > > Thanks, > Mike > > > > On 4/27/17, 4:02 PM, "Matt Riedemann" wrote: > > On 4/27/2017 4:52 PM, Eric Fried wrote: > > Y'all- > > > > TL;DR: Does glance ever really need/use multiple endpoint URLs? > > > > I'm working on bp use-service-catalog-for-endpoints[1], which intends > > to deprecate disparate conf options in various groups, and centralize > > acquisition of service endpoint URLs. The idea is to introduce > > nova.utils.get_service_url(group) -- note singular 'url'. > > > > One affected conf option is [glance]api_servers[2], which currently > > accepts a *list* of endpoint URLs. The new API will only ever return > *one*. > > > > Thus, as planned, this blueprint will have the side effect of > > deprecating support for multiple glance endpoint URLs in Pike, and > > removing said support in Queens. > > > > Some have asserted that there should only ever be one endpoint URL for > > a given service_type/interface combo[3]. I'm fine with that - it > > simplifies things quite a bit for the bp impl - but wanted to make sure > > there were no loudly-dissenting opinions before we get too far down this > > path. > > > > [1] > > > https://blueprints.launchpad.net/nova/+spec/use-service-catalog-for-endpoints > > [2] > > > https://github.com/openstack/nova/blob/7e7bdb198ed6412273e22dea72e37a6371fce8bd/nova/conf/glance.py#L27-L37 > > [3] > > > http://eavesdrop.openstack.org/irclogs/%23openstack-keystone/%23openstack-keystone.2017-04-27.log.html#t2017-04-27T20:38:29 > > > > Thanks, > > Eric Fried (efried) > > . > > > > > __ > > OpenStack Development Mailing List (not for usage questions) > > Unsubscribe: > openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > > +openstack-operators > > -- > > Thanks, > > Matt > > __ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > ___ > OpenStack-operators mailing list > openstack-operat...@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators -- Cheers, ~Blairo __ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev