Hi Yash, 1) To avoid conflicts with other sensors, the PluginMetrics implementation will append a suffix to sensor names to unique identify the plugin (based on the class name and tags). Also I changed the semantics of the sensor() method to only create sensors (originally it was get or create). If a sensor with the same name already exists, the method will throw. 2) Tags will be automatically added to metrics and sensors to unique identify the plugin. For Connect plugins, the connector name, task id and alias can be added if available. The class implementing PluginMetrics will be similar to ConnectMetrics, as in it will provide a simplified API wrapping Metrics. I'm planning to use PluginMetrics for Connect plugin too and should not need to interact with ConnectMetrics. 3) Right, I fixed the last rejected alternative.
Thanks, Mickael On Thu, Jan 26, 2023 at 4:04 PM Mickael Maison <mickael.mai...@gmail.com> wrote: > > Hi Federico, > > - The metricName() method does not register anything, it just builds a > MetricName instance which is just a container holding a name, group, > description and tags for a metric. Each time it is called, it returns > a new instance. If called with the same arguments, the returned value > will be equal. > - Initially I just copied the API of Metrics. I made some small > changes so the metric and sensor methods are a bit more similar > - Good catch! I fixed the example. > > Thanks, > Mickael > > > On Thu, Jan 26, 2023 at 3:54 PM Mickael Maison <mickael.mai...@gmail.com> > wrote: > > > > Hi Chris, > > > > 1) I updated the KIP to only mention the interface. > > 2) This was a mistake. I've added ReplicationPolicy to the list of plugins. > > > > Thanks, > > Mickael > > > > On Tue, Jan 24, 2023 at 11:16 AM Yash Mayya <yash.ma...@gmail.com> wrote: > > > > > > Hi Mickael, > > > > > > Thanks for the updated KIP, this is looking really good! I had a couple > > > more questions - > > > > > > 1) Sensor names need to be unique across all groups for a `Metrics` > > > instance. How are we planning to avoid naming clashes (both between > > > different plugins as well as with pre-defined sensors)? > > > > > > 2) Connect has a `ConnectMetrics` wrapper around `Metrics` via which > > > rebalance / worker / connector / task metrics are recorded. Could you > > > please elaborate in the KIP how the plugin metrics for connectors / tasks > > > will inter-operate with this? > > > > > > Another minor point is that the third rejected alternative appears to be > > > an > > > incomplete sentence? > > > > > > Thanks, > > > Yash > > > > > > On Fri, Jan 13, 2023 at 10:56 PM Mickael Maison <mickael.mai...@gmail.com> > > > wrote: > > > > > > > Hi, > > > > > > > > I've updated the KIP based on the feedback. > > > > > > > > Now instead of receiving a Metrics instance, plugins get access to > > > > PluginMetrics that exposes a much smaller API. I've removed the > > > > special handling for connectors and tasks and they must now implement > > > > the Monitorable interface as well to use this feature. Finally the > > > > goal is to allow all plugins (apart from metrics reporters) to use > > > > this feature. I've listed them all (there are over 30 pluggable APIs) > > > > but I've not added the list in the KIP. The reason is that new plugins > > > > could be added in the future and instead I'll focus on adding support > > > > in all the place that instantiate classes. > > > > > > > > Thanks, > > > > Mickael > > > > > > > > On Tue, Jan 10, 2023 at 7:00 PM Mickael Maison > > > > <mickael.mai...@gmail.com> > > > > wrote: > > > > > > > > > > Hi Chris/Yash, > > > > > > > > > > Thanks for taking a look and providing feedback. > > > > > > > > > > 1) Yes you're right, when using incompatible version, metrics() would > > > > > trigger NoSuchMethodError. I thought using the context to pass the > > > > > Metrics object would be more idiomatic for Connect but maybe > > > > > implementing Monitorable would be simpler. It would also allow other > > > > > Connect plugins (transformations, converters, etc) to register > > > > > metrics. So I'll make that change. > > > > > > > > > > 2) As mentioned in the rejected alternatives, I considered having a > > > > > PluginMetrics class/interface with a limited API. But since Metrics is > > > > > part of the public API, I thought it would be simpler to reuse it. > > > > > That said you bring interesting points so I took another look today. > > > > > It's true that the Metrics API is pretty complex and most methods are > > > > > useless for plugin authors. I'd expect most use cases only need one > > > > > addMetric and one sensor methods. Rather than subclassing Metrics, I > > > > > think a delegate/forwarding pattern might work well here. A > > > > > PluginMetric class would forward its method to the Metrics instance > > > > > and could perform some basic validations such as only letting plugins > > > > > delete metrics they created, or automatically injecting tags with the > > > > > class name for example. > > > > > > > > > > 3) Between the clients, brokers, streams and connect, Kafka has quite > > > > > a lot! In practice I think registering metrics should be beneficial > > > > > for all plugins, I think the only exception would be metrics reporters > > > > > (which are instantiated before the Metrics object). I'll try to build > > > > > a list of all plugin types and add that to the KIP. > > > > > > > > > > Thanks, > > > > > Mickael > > > > > > > > > > > > > > > > > > > > On Tue, Dec 27, 2022 at 4:54 PM Chris Egerton > > > > > <chr...@aiven.io.invalid> > > > > wrote: > > > > > > > > > > > > Hi Yash, > > > > > > > > > > > > Yes, a default no-op is exactly what I had in mind should the > > > > Connector and > > > > > > Task classes implement the Monitorable interface. > > > > > > > > > > > > Cheers, > > > > > > > > > > > > Chris > > > > > > > > > > > > On Tue, Dec 20, 2022 at 2:46 AM Yash Mayya <yash.ma...@gmail.com> > > > > wrote: > > > > > > > > > > > > > Hi Mickael, > > > > > > > > > > > > > > Thanks for creating this KIP, this will be a super useful feature > > > > > > > to > > > > > > > enhance existing connectors in the Kafka Connect ecosystem. > > > > > > > > > > > > > > I have some similar concerns to the ones that Chris has outlined > > > > above, > > > > > > > especially with regard to directly exposing Connect's Metrics > > > > > > > object > > > > to > > > > > > > plugins. I believe it would be a lot friendlier to developers if > > > > > > > we > > > > instead > > > > > > > exposed wrapper methods in the context classes - such as one for > > > > > > > registering a new metric, one for recording metric values and so > > > > > > > on. > > > > This > > > > > > > would also have the added benefit of minimizing the surface area > > > > > > > for > > > > > > > potential misuse by custom plugins. > > > > > > > > > > > > > > > for connectors and tasks they should handle the > > > > > > > > metrics() method returning null when deployed on > > > > > > > > an older runtime. > > > > > > > > > > > > > > I believe this won't be the case, and instead they'll need to > > > > > > > handle > > > > a > > > > > > > `NoSuchMethodError` right? This is similar to previous KIPs that > > > > added > > > > > > > methods to connector context classes and will arise due to an > > > > > > > incompatibility between the `connect-api` dependency that a plugin > > > > will be > > > > > > > compiled against versus what it will actually get at runtime. > > > > > > > > > > > > > > Hi Chris, > > > > > > > > > > > > > > > WDYT about having the Connector and Task classes > > > > > > > > implement the Monitorable interface, both for > > > > > > > > consistency's sake, and to prevent classloading > > > > > > > > headaches? > > > > > > > > > > > > > > Are you suggesting that the framework should configure connectors > > > > > > > / > > > > tasks > > > > > > > with a Metrics instance during their startup rather than the > > > > connector / > > > > > > > task asking the framework to provide one? In this case, I'm > > > > > > > guessing > > > > you're > > > > > > > envisioning a default no-op implementation for the metrics > > > > configuration > > > > > > > method rather than the framework having to handle the case where > > > > > > > the > > > > > > > connector was compiled against an older version of Connect right? > > > > > > > > > > > > > > Thanks, > > > > > > > Yash > > > > > > > > > > > > > > On Wed, Nov 30, 2022 at 1:38 AM Chris Egerton > > > > <chr...@aiven.io.invalid> > > > > > > > wrote: > > > > > > > > > > > > > > > Hi Mickael, > > > > > > > > > > > > > > > > Thanks for the KIP! This seems especially useful to reduce the > > > > > > > > implementation cost and divergence in behavior for connectors > > > > > > > > that > > > > choose > > > > > > > > to publish their own metrics. > > > > > > > > > > > > > > > > My initial thoughts: > > > > > > > > > > > > > > > > 1. Are you certain that the default implementation of the > > > > > > > > "metrics" > > > > > > > method > > > > > > > > for the various connector/task context classes will be used on > > > > older > > > > > > > > versions of the Connect runtime? My understanding was that a > > > > > > > > NoSuchMethodError (or some similar classloading exception) > > > > > > > > would be > > > > > > > thrown > > > > > > > > in that case. If that turns out to be true, WDYT about having > > > > > > > > the > > > > > > > Connector > > > > > > > > and Task classes implement the Monitorable interface, both for > > > > > > > > consistency's sake, and to prevent classloading headaches? > > > > > > > > > > > > > > > > 2. Although I agree that administrators should be careful about > > > > which > > > > > > > > plugins they run on their clients, Connect clusters, etc., I > > > > wonder if > > > > > > > > there might still be value in wrapping the Metrics class behind > > > > > > > > a > > > > new > > > > > > > > interface, for a few reasons: > > > > > > > > > > > > > > > > a. Developers and administrators may still make mistakes, and > > > > > > > > if > > > > we can > > > > > > > > reduce the blast radius by preventing plugins from, e.g., > > > > > > > > closing > > > > the > > > > > > > > Metrics instance we give them, it may be worth it. This could > > > > > > > > also > > > > be > > > > > > > > accomplished by forbidding plugins from invoking these methods, > > > > > > > > and > > > > > > > giving > > > > > > > > them a subclass of Metrics that throws > > > > UnsupportedOperationException from > > > > > > > > these methods. > > > > > > > > > > > > > > > > b. If we don't know of any reasonable use cases for closing > > > > > > > > the > > > > > > > instance, > > > > > > > > adding new reporters, removing metrics, etc., it can make the > > > > > > > > API > > > > cleaner > > > > > > > > and easier for developers to grok if they don't even have the > > > > option to > > > > > > > do > > > > > > > > any of those things. > > > > > > > > > > > > > > > > c. Interoperability between plugins that implement Monitorable > > > > and > > > > > > > their > > > > > > > > runtime becomes complicated. For example, a connector may be > > > > > > > > built > > > > > > > against > > > > > > > > a version of Kafka that introduces new methods for the Metrics > > > > class, > > > > > > > which > > > > > > > > introduces risks of incompatibility if its developer chooses to > > > > take > > > > > > > > advantage of these methods without realizing that they will not > > > > > > > > be > > > > > > > > available on Connect runtimes built against an older version of > > > > Kafka. > > > > > > > With > > > > > > > > a wrapper interface, we at least have a chance to isolate these > > > > issues so > > > > > > > > that the Metrics class can be expanded without adding footguns > > > > > > > > for > > > > > > > plugins > > > > > > > > that implement Monitorable, and to call out potential > > > > > > > > compatibility > > > > > > > > problems in documentation more clearly if/when we do expand the > > > > wrapper > > > > > > > > interface. > > > > > > > > > > > > > > > > 3. It'd be nice to see a list of exactly which plugins will be > > > > able to > > > > > > > take > > > > > > > > advantage of the new Monitorable interface. > > > > > > > > > > > > > > > > Looking forward to your thoughts! > > > > > > > > > > > > > > > > Cheers, > > > > > > > > > > > > > > > > Chris > > > > > > > > > > > > > > > > On Mon, Nov 7, 2022 at 11:42 AM Mickael Maison < > > > > mickael.mai...@gmail.com > > > > > > > > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > I have opened KIP-877 to make it easy for plugins and > > > > > > > > > connectors > > > > to > > > > > > > > > register their own metrics: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://eu01.z.antigena.com/l/9lWv8kbU9CKs2LajwgfKF~yMNQVM7rWRxYmYVNrHU_2nQbisTiXYZdowNfQ-NcgF1uai2lk-sv6hJASnbdr_gqVwyVae_~y-~oq5yQFgO_-IHD3UGDn3lsIyauAG2tG6giPJH-9yCYg3Hwe26sm7nep258qB6SNXRwpaVxbU3SaVTybfLQVvTn_uUlHKMhmVnpnc1dUnusK6x4j8JPPQQ1Ce~rrg-nsSLouHHMf0ewmpsFNy4BcbMaqHd4Y > > > > > > > > > > > > > > > > > > Let me know if you have any feedback or suggestions. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > Mickael > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
