mlbiscoc opened a new pull request, #2902: URL: https://github.com/apache/solr/pull/2902
https://issues.apache.org/jira/browse/SOLR-17587 <!-- _(If you are a project committer then you may remove some/all of the following template.)_ Before creating a pull request, please file an issue in the ASF Jira system for Solr: * https://issues.apache.org/jira/projects/SOLR For something minor (i.e. that wouldn't be worth putting in release notes), you can skip JIRA. To create a Jira issue, you will need to create an account there first. The title of the PR should reference the Jira issue number in the form: * SOLR-####: <short description of problem or changes> SOLR must be fully capitalized. A short description helps people scanning pull requests for items they can work on. Properly referencing the issue in the title ensures that Jira is correctly updated with code review comments and commits. --> # Description Solr's Prometheus writer duplicates `# TYPE <metric name> <prometheus metric type>` in it's exposition format for `core`registry metrics. This is an illegal format and depending on the technologies prometheus exposition verification for example `Telegraf`, this will fail. For Prometheus server itself, this still passes and collects the metrics just fine for some reason. This is because the Prometheus Writer takes Dropwizard registries and exports them to Prometheus Registries to expose them in Prometheus format. Solr creates Dropwizard registry for every `core` and differentiates the metrics that way even though they have the same metric names. For prometheus, this creates an issue in that metrics should be differentiated in it's attributes and tags. So when the metrics are output with the Prometheus response writer, it duplicates the `TYPE` information because it is a registry for every `core` and doesn't know that the other `core` registries have the same metric name and results in duplicate `TYPE` information. # Solution When metrics are going to be exported for prometheus, we merge all the `core` Dropwizard metric registries into a single registry and export that registry into prometheus. Duplicate metric names in a registry is not allowed in prometheus, so we will also append the core name to the Dropwizard metric to differentiate which metric belongs to what core and parse the labels accordingly. This also allowed to clean up and simply some of the `SolrPrometheusCoreFormatter` code. # Tests Updated the test accordingly with the coreName existing in the Dropwizard metric names and it's parsing. Also added an assert in `testPrometheusStructureOutput` to confirm there is no duplicate `TYPE` information in prometheus output. # Checklist Please review the following and check all that apply: - [ ] I have reviewed the guidelines for [How to Contribute](https://github.com/apache/solr/blob/main/CONTRIBUTING.md) and my code conforms to the standards described there to the best of my ability. - [ ] I have created a Jira issue and added the issue ID to my pull request title. - [ ] I have given Solr maintainers [access](https://help.github.com/en/articles/allowing-changes-to-a-pull-request-branch-created-from-a-fork) to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation) - [ ] I have developed this patch against the `main` branch. - [ ] I have run `./gradlew check`. - [ ] I have added tests for my changes. - [ ] I have added documentation for the [Reference Guide](https://github.com/apache/solr/tree/main/solr/solr-ref-guide) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
