>can you give an example of what parent.config looks like when 2 ds's share an origin and have different a different topology?
Answering because I encountered this directly, when rewriting parent.config. For example: Suppose you have one Delivery Service: XML_ID: foo Type: HTPT_LIVE_NATL Query String Handling: 1 - ignore in cache key, and pass up Origin Server Base URL: http://foo.example.net And another Delivery Service: XML_ID: bar Type: HTPT_LIVE_NATL Query String Handling: 1 - ignore in cache key, and pass up Origin Server Base URL: http://foo.example.net ATS only supports unique `dest_domain` entries in parent.config. Therefore, the parent.config generated for a server assigned to both of these Delivery Services with either be: dest_domain=foo.example.net port=80 go_direct=true Or dest_domain=foo.example.net port=80 go_direct=false qstring=consider Right now, it's arbitrary which Perl Traffic Ops inserts, and Perl provides no warning or error of any kind (the pending Go parent.config PR logs an error). Whichever is arbitrarily inserted, the resulting remaps for the other delivery service will be wrong. Either `foo` requests will drop the query string when they shouldn't, and go to the mid when they shouldn't; or `bar` requests will use the query string and skip the mid when it shouldn't. Does that make sense? The only correct solution, is to somehow prevent different DSes having the same origin, and tell tenants they must use CNAMEs if they need. This isn't a bug in Traffic Control. ATS fundamentally doesn't support multiple remap rules with the same parent FQDN with different configurations. Hence, Traffic Control needs to prohibit that. On Tue, Dec 18, 2018 at 12:24 PM Jeremy Mitchell <mitchell...@gmail.com> wrote: > brennan, > > can you give an example of what parent.config looks like when 2 ds's share > an origin and have different a different topology? > > jeremy > > On Tue, Dec 18, 2018 at 11:39 AM Fieck, Brennan <brennan_fi...@comcast.com > > > wrote: > > > To be clear, the "Warning" I'm talking about would happen at startup, but > > I'd like a UI-only constraint to come with that to disallow using the API > > to bind the same origin to multiple Delivery Services with varying > > topography requirements. It wouldn't change the existing data, but > prevent > > users from creating more bad data. > > > > "warning" doesn't really sufficiently describe that, my bad. > > ________________________________________ > > From: Fieck, Brennan <brennan_fi...@comcast.com> > > Sent: Tuesday, December 18, 2018 11:24 AM > > To: dev@trafficcontrol.apache.org > > Subject: Re: [EXTERNAL] Re: Origins assigned to Multipe Delivery Services > > produces indeterminate parent.config > > > > Well the cost of fixing this bug is a constraint on the data. Unless we > > make it a UI-only constraint - which I'm personally against - there must > be > > some point in the future where ATC cannot reasonably be expected to work > > with data that violates that constraint. The question is when that should > > occur, which should likely happen at a minor version release. Minor not > > major because it doesn't involve a change in data structures, merely > > relationships between them - in my opinion that's a minor version change > > but that's definitely up for debate. With several release candidates for > > 3.0.0 that _doesn't_ include this restriction already in the wild, I > > wouldn't recommend putting it in there. That means to fix the bug as soon > > as possible it should go in 3.1.0 which should be the target of "master" > > after the 3.0.0 release is cut from it. > > > > So I'd recommend immediately implementing the constraint in master with a > > refusal to upgrade with bad data, and backport a warning about the future > > behavior into 3.0.0 or as part of a 3.0.1 provided we had more changes > that > > would warrant a micro version bump. > > ________________________________________ > > From: Gray, Jonathan <jonathan_g...@comcast.com> > > Sent: Tuesday, December 18, 2018 9:34 AM > > To: dev@trafficcontrol.apache.org > > Subject: Re: [EXTERNAL] Re: Origins assigned to Multipe Delivery Services > > produces indeterminate parent.config > > > > -1 Holding an ATC upgrade hostage to data cleanup seems like a bad idea. > > The issue isn't great, but it's also not new. We should allow teams to > fix > > their data at their normal paces if it doesn't create significant > overhead > > or an inherant blocker for new functionality or correction of other major > > problems imho. > > > > Jonathan G > > > > > > On 12/18/18, 9:28 AM, "Fieck, Brennan" <brennan_fi...@comcast.com> > wrote: > > > > Another option is we could detect collisions at startup and simply > > refuse to continue with the upgrade until the data is fixed. That would > > allow people using the now-unsupported data format to continue to use > their > > old versions of Traffic Ops without wrecking their database, but also > > provide an incentive to clean up the data. > > ________________________________________ > > From: Gray, Jonathan <jonathan_g...@comcast.com> > > Sent: Tuesday, December 18, 2018 5:12 AM > > To: dev@trafficcontrol.apache.org > > Subject: Re: [EXTERNAL] Re: Origins assigned to Multipe Delivery > > Services produces indeterminate parent.config > > > > I'm generally a fan of constrain your data in your database, but not > > necessarily exclusively. I see this as a one-way cleanup/conversion so > it > > doesn't need to be configurable; otherwise you have to ask the question > > what happens if someone turns it off. That said, something in the UI > layer > > would be nice to prevent spending significant quantities of time > building a > > complex DS only to have it fail to post for reasons that could have been > > known earlier. > > > > The way my brain works in this case: > > If !unique_constraint_exists_query() > > If has_duplicates_query() > > show_warning() > > else > > add_unique_constraint() > > > > to which the API and UI configuration could also make use of > > unique_constraint_exists_query() to drive additional layer constraints if > > desired. > > > > Jonathan G > > > > On 12/17/18, 1:11 PM, "Rawlin Peters" <rawlin.pet...@gmail.com> > wrote: > > > > That is an interesting idea...detect at TO startup whether or not > > there are duplicate origins and operate in a "prevent duplicate > > origins" state if no duplicates are found or "prevent conflicting > > DS > > topologies" state if duplicates are found? So once operators have > > replaced all the duplicate origins with CNAMEs, TO will > essentially > > operate in a "prohibit all duplicate origins" state. That would > > probably make for a simpler transition, but I'd want to remove > that > > logic in a following release that strictly prohibits duplicate > > origins > > (assuming that the community agrees we should prohibit duplicate > > origins altogether). > > > > As for DB constraints vs UI, I was thinking those DS-type > > constraints > > I pointed out would live in the API. It would basically be added > > validation in the deliveryservices POST/PUT endpoint that checks > > the > > DB for existing DSes that conflict with the requested DS. > > > > - Rawlin > > > > On Mon, Dec 17, 2018 at 12:35 PM Gray, Jonathan > > <jonathan_g...@comcast.com> wrote: > > > > > > These kinds of conditions should be detectable with a > > sufficiently advanced SQL query. Is it possible to add the constraint if > > it passes and emit a warning during TO startup otherwise? That would let > > you know the condition exists at startup but not getting in your way and > > keep you out of trouble once you've cleaned up. We made a mistake early > > on, but this would acknowledge it was bad and encourage it to be fixed at > > the speed of operations teams. Also this puts the constraint in the > > database rather than the UI which is really where the contention is for > > usability. > > > > > > Jonathan G > > > > > > > > > On 12/17/18, 11:38 AM, "Rawlin Peters" < > rawlin.pet...@gmail.com> > > wrote: > > > > > > We occasionally discuss this issue but haven't tackled it > > yet. I think > > > the main issue is just that duplicate origins have been > > allowed since > > > the beginning, and now everyone's Traffic Ops could be > > littered with > > > duplicate origins. Also, depending on the config of the > > duplicate > > > delivery services, the origins might not be in conflict at > > all (if > > > they don't have different topology constraints). I would > > love for us > > > to just add a uniqueness constraint, but there would need > to > > be a fair > > > amount of warning to the community before doing so and > might > > > invalidate a significant amount of valid use cases. > > Operators would > > > need time to make DNS CNAME records for the duplicate > > origins and > > > update their DSes to use the different CNAMEs. > > > > > > I think as a good first step to eliminating the use of > > duplicate > > > origins altogether, we should identify which "topology > > constraints" > > > actually cause conflicting config when used with duplicate > > origins and > > > prevent creating DSes with duplicate origins _if it would > > cause a > > > conflict with an existing DS that uses the same origin_. > > > > > > For instance, I believe an HTTP and DNS-type DS can live > > happily > > > side-by-side using the same origin (probably need different > > > routing_names?), but scenarios like HTTP and HTTP_LIVE, or > > DNS and > > > HTTP_NO_CACHE sharing the same origin will cause conflicts > > for sure. > > > So maybe we can start by making sure the DS types "match" > > when using > > > the same origin: > > > HTTP + DNS: possibly good, if they have different routing > > names? > > > HTTP_LIVE + HTTP_LIVE_NATNL: bad > > > HTTP_NO_CACHE + [any other type]: bad > > > HTTP_LIVE + HTTP: bad > > > etc. > > > > > > There are most likely other conflict scenarios that don't > > involve the > > > DS types, but I think this would be a good start. In the > > future with > > > Delivery Service Topologies (aka Flexible Cachegroups aka > > Bring Your > > > Own Topology), we might be able to prohibit assigning a DS > > to a > > > Topology if the DS's origin is already used by another DS > in > > a > > > different Topology. > > > > > > - Rawlin > > > > > > On Mon, Dec 17, 2018 at 10:52 AM Fieck, Brennan > > > <brennan_fi...@comcast.com> wrote: > > > > > > > > As some of you may be aware, `parent.config` files > > generated by Traffic Ops can vary wildly when an origin is assigned to > > multiple Delivery Services. This results in undefined behavior. I'm told > > that the conflict only happens when two Delivery Services with different > > "topology requirements" use the same origin, whatever that means (content > > routing type?). Regardless, the issue should be addressed. The obvious > > solution is to put in place a database constraint that prevents an origin > > from being assigned to more that one Delivery Service with API checks in > > place that would provide helpful error messages when an attempt is made > to > > violate the constraint. However, would that mess with things like > > Multi-Site Origin? Or is it just not viable for some other reason? If it > is > > a good solution, I'm prepared to work on a fix that utilizes it. > > > > > > > > > > > > > > > > >
