Hi Rajini, One quick question I was wondering about is whether this could be used to update the inter-broker protocol version or the message format version? Potentially then we'd only need one rolling restart to upgrade the cluster. I glanced quickly through the uses of this config in the code and it seems like it might be possible. Not sure if there are any complications you or others can think of.
Thanks, Jason On Tue, Nov 28, 2017 at 2:48 PM, Rajini Sivaram <rajinisiva...@gmail.com> wrote: > Hi Colin, > > Thank you for reviewing the KIP. > > *kaka-configs.sh* will be converted to use *AdminClient* under KAFKA-5722. > This is targeted for the next release (1.1.0). Under this KIP, we will > implement *AdminClient#alterConfigs* for the dynamic configs listed in the > KIP. This will include validation of the configs and will return > appropriate errors if configs are invalid. Integration tests will also be > added using AdmnClient. Only the actual conversion of ConfigCommand to use > AdminClient will be left to be done under KAFKA-5722. > > Once KAFKA-5722 is implemented,* kafka-confgs.sh* can be used to obtain the > current configuration, which can be redirected to a text file to create a > static *server.properties* file. This should help when downgrading - but it > does require brokers to be running. We can also document how to obtain the > properties using *zookeeper-shell.sh* while downgrading if brokers are > down. > > If we rename properties, we should add the new property to ZK based on the > value of the old property when the upgraded broker starts up. But we would > probably leave the old property as is. The old property will be returned > and used as a synonym only as long as the broker is on a version where it > is still valid. But it can remain in ZK and be updated if downgrading - it > will be up to the user to update the old property if downgrading or delete > it if not needed. Renaming properties is likely to be confusing in any case > even without dynamic configs, so hopefully it will be very rare. > > > Rajini > > On Tue, Nov 28, 2017 at 7:47 PM, Colin McCabe <cmcc...@apache.org> wrote: > > > Hi Rajini, > > > > This seems like a nice improvement! > > > > One thing that is a bit concerning is that, if bin/kafka-configs.sh is > > used, there is no way for the broker to give feedback or error > > messages. The broker can't say "sorry, I can't reconfigure that in that > > way." Or even "that configuration property is not reconfigurable in > > this version of the software." It seems like in the examples give, > > users will simply set a configuration using bin/kafka-configs.sh, but > > then they have to check the broker log files to see if it could actually > > be applied. And even if it couldn't be applied, then it still lingers > > in ZooKeeper. > > > > This seems like it would lead to a lot of user confusion, since they get > > no feedback when reconfiguring something. For example, there will be a > > lot of scenarios where someone finds a reconfiguration command on > > Google, runs it, but then it doesn't do anything because the software > > version is different. And there's no error message or feedback about > > this. It just doesn't work. > > > > To prevent this, I think we should convert bin/kafka-configs.sh to use > > AdminClient's AlterConfigsRequest. This allows us to detect scenarios > > where, because of a typo, different software version, or a value of the > > wrong type (eg. string vs. int), the given configuration cannot be > > applied. We really should convert kafka-configs.sh to use AdminClient > > anyway, for all the usual reasons-- people want to lock down ZooKeeper, > > ACLs should be enforced, internal representations should be hidden, we > > should support environments where ZK is not exposed, etc. etc. > > > > Another issue that I see here is, how does this interact with downgrade? > > Presumably, if the user downgrades to a version that doesn't support > > KIP-226, all the dynamic configurations stored in ZK revert to whatever > > value they have in the local config files. Do we need to have a utility > > that can reify the actual applied configuration into a local text file, > > to make downgrades less painful? > > > > With regard to upgrades, what happens if we change the name of a > > configuration key in the future? For example, if we decide to rename > > min.insync.replicas to min.in.sync.replicas, presumably we will > > deprecate the old key name. And then perhaps it will be removed in a > > future release, such as Apache Kafka 2.0. In this scenario, should the > > Kafka upgrade process change the name of the configuration key in ZK > > from min.insync.replicas to min.in.sync.replicas? Obviously this will > > make downgrades harder, if so. But if it doesn't, then removing > > deprecated configuration key synonyms might become very difficult. > > > > best, > > Colin > > > > > > On Wed, Nov 22, 2017, at 12:52, Rajini Sivaram wrote: > > > Hi Tom, > > > > > > No, I am not proposing this as a way to configure replication quotas. > > > When > > > you describe broker configs using AdminClient, you will see all the > > > configs > > > persisted in /configs/brokers/<brokerId> in ZooKeeper and this includes > > > leader.replication.throttled.rate, follower.replication.throttled.rate > > > etc. But > > > the broker configs that can be altered using AdminClient as a result of > > > this KIP are those explicitly stated in the KIP (does not include any > of > > > the quota configs). > > > > > > Regards, > > > > > > Rajini > > > > > > On Wed, Nov 22, 2017 at 7:54 PM, Tom Bentley <t.j.bent...@gmail.com> > > > wrote: > > > > > > > Hi Rajini, > > > > > > > > Just to clarify, are you proposing this as a way to configure > > interbroker > > > > throttling/quotas? I don't think you are, just wanted to check (since > > > > KIP-179 proposes a different mechanism for setting them which > supports > > > > their automatic removal). > > > > > > > > Cheers, > > > > > > > > Tom > > > > > > > > On 22 November 2017 at 18:28, Rajini Sivaram < > rajinisiva...@gmail.com> > > > > wrote: > > > > > > > > > I have made an update to the KIP to optionally return all the > config > > > > > synonyms in *DescribeConfigsResponse*. The synonyms are returned in > > the > > > > > order of precedence. AlterConfigsResponse will not be modified by > the > > > > KIP. > > > > > Since many configs already have various overrides (e.g. topic > configs > > > > with > > > > > broker overrides, security properties with listener name overrides) > > and > > > > we > > > > > will be adding more levels with dynamic configs, it will be useful > to > > > > > obtain the full list in order of precedence. > > > > > > > > > > On Tue, Nov 21, 2017 at 11:24 AM, Rajini Sivaram < > > > > rajinisiva...@gmail.com> > > > > > wrote: > > > > > > > > > > > Hi Ted, > > > > > > > > > > > > You can quote the config name, but it is not necessary for > > deleting a > > > > > > config since the name doesn't contain any special characters that > > > > > requires > > > > > > quoting. > > > > > > > > > > > > On Mon, Nov 20, 2017 at 9:20 PM, Ted Yu <yuzhih...@gmail.com> > > wrote: > > > > > > > > > > > >> Thanks for the quick response. > > > > > >> > > > > > >> It seems the config following --delete-config should be quoted. > > > > > >> > > > > > >> Cheers > > > > > >> > > > > > >> On Mon, Nov 20, 2017 at 12:02 PM, Rajini Sivaram < > > > > > rajinisiva...@gmail.com > > > > > >> > > > > > > >> wrote: > > > > > >> > > > > > >> > Ted, > > > > > >> > > > > > > >> > Have added an example for --delete-config. > > > > > >> > > > > > > >> > On Mon, Nov 20, 2017 at 7:42 PM, Ted Yu <yuzhih...@gmail.com> > > > > wrote: > > > > > >> > > > > > > >> > > bq. There is a --delete-config option > > > > > >> > > > > > > > >> > > Consider adding a sample with the above option to the KIP. > > > > > >> > > > > > > > >> > > Thanks > > > > > >> > > > > > > > >> > > On Mon, Nov 20, 2017 at 11:36 AM, Rajini Sivaram < > > > > > >> > rajinisiva...@gmail.com> > > > > > >> > > wrote: > > > > > >> > > > > > > > >> > > > Hi Ted, > > > > > >> > > > > > > > > >> > > > Thank you for reviewing the KIP. > > > > > >> > > > > > > > > >> > > > *Would decreasing network/IO threads be supported ?* > > > > > >> > > > Yes, As described in the KIP, some connections will be > > closed if > > > > > >> > network > > > > > >> > > > thread count is reduced (and reconnections will be > > processed on > > > > > >> > remaining > > > > > >> > > > threads) > > > > > >> > > > > > > > > >> > > > *What if some keys in configs are not in the Set returned > > > > > >> > > > by reconfigurableConfigs()? Would exception be thrown ?* > > > > > >> > > > No, *reconfigurableConfigs() *will be used to decide which > > > > classes > > > > > >> are > > > > > >> > > > notified when a configuration update is made*. > > > > > >> > **reconfigure(Map<String, > > > > > >> > > ?> > > > > > >> > > > configs)* will be invoked with all of the configured > > configs of > > > > > the > > > > > >> > > broker, > > > > > >> > > > similar to *configure(Map<String, ?> configs). *For > > example, > > > > > when > > > > > >> > > > *SslChannelBuilder* is made reconfigurable, it could just > > > > create a > > > > > >> new > > > > > >> > > > SslFactory with the latest configs, using the same code as > > > > > >> > *configure()*. > > > > > >> > > > We avoid reconfiguring *SslChannelBuilder *unnecessarily*, > > *for > > > > > >> example > > > > > >> > > if > > > > > >> > > > a topic config has changed, since topic configs are not > > listed > > > > in > > > > > >> the > > > > > >> > > > *SslChannelBuilder#**reconfigurableConfigs().* > > > > > >> > > > > > > > > >> > > > *The sample commands for bin/kafka-configs include > > > > '--add-config'. > > > > > >> > Would > > > > > >> > > > there be '--remove-config' ?* > > > > > >> > > > bin/kafka-configs.sh is an existing tool whose parameters > > will > > > > not > > > > > >> be > > > > > >> > > > modified by this KIP. There is a --delete-config option. > > > > > >> > > > > > > > > >> > > > *ssl.keystore.password appears a few lines above. Would > > there be > > > > > any > > > > > >> > > > issue with mixture of connections (with old and new > > password) ?* > > > > > >> > > > No, passwords (and the actual keystore) are only used > during > > > > > >> > > > authentication. Any channel created using the old > SslFactory > > > > will > > > > > >> not > > > > > >> > be > > > > > >> > > > impacted. > > > > > >> > > > > > > > > >> > > > Regards, > > > > > >> > > > > > > > > >> > > > Rajini > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > On Mon, Nov 20, 2017 at 4:39 PM, Ted Yu < > > yuzhih...@gmail.com> > > > > > >> wrote: > > > > > >> > > > > > > > > >> > > > > bq. (e.g. increase network/IO threads) > > > > > >> > > > > > > > > > >> > > > > Would decreasing network/IO threads be supported ? > > > > > >> > > > > > > > > > >> > > > > bq. void reconfigure(Map<String, ?> configs); > > > > > >> > > > > > > > > > >> > > > > What if some keys in configs are not in the Set returned > > by > > > > > >> > > > > reconfigurableConfigs() > > > > > >> > > > > ? Would exception be thrown ? > > > > > >> > > > > If so, please specify which exception would be thrown. > > > > > >> > > > > > > > > > >> > > > > The sample commands for bin/kafka-configs include > > > > > '--add-config'. > > > > > >> > > > > Would there be '--remove-config' ? > > > > > >> > > > > > > > > > >> > > > > bq. Existing connections will not be affected, new > > connections > > > > > >> will > > > > > >> > use > > > > > >> > > > the > > > > > >> > > > > new keystore. > > > > > >> > > > > > > > > > >> > > > > ssl.keystore.password appears a few lines above. Would > > there > > > > be > > > > > >> any > > > > > >> > > issue > > > > > >> > > > > with mixture of connections (with old and new password) > ? > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > > > Cheers > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > > > On Mon, Nov 20, 2017 at 5:57 AM, Rajini Sivaram < > > > > > >> > > rajinisiva...@gmail.com > > > > > >> > > > > > > > > > >> > > > > wrote: > > > > > >> > > > > > > > > > >> > > > > > Hi all, > > > > > >> > > > > > > > > > > >> > > > > > I have submitted KIP-226 to enable dynamic > > reconfiguration > > > > of > > > > > >> > brokers > > > > > >> > > > > > without restart: > > > > > >> > > > > > > > > > > >> > > > > > https://cwiki.apache.org/ > confluence/display/KAFKA/KIP- > > > > > >> > > > > > 226+-+Dynamic+Broker+Configuration > > > > > >> > > > > > > > > > > >> > > > > > The KIP proposes to extend the current dynamic > > replication > > > > > quota > > > > > >> > > > > > configuration for brokers to support dynamic > > reconfiguration > > > > > of > > > > > >> a > > > > > >> > > > limited > > > > > >> > > > > > set of configuration options that are typically > updated > > > > during > > > > > >> the > > > > > >> > > > > lifetime > > > > > >> > > > > > of a broker. > > > > > >> > > > > > > > > > > >> > > > > > Feedback and suggestions are welcome. > > > > > >> > > > > > > > > > > >> > > > > > Thank you... > > > > > >> > > > > > > > > > > >> > > > > > Regards, > > > > > >> > > > > > > > > > > >> > > > > > Rajini > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > >
