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 > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > > > > > > > > > > >
