## Description
Metrics Platform provides the least-effort approach to instrument WikiLambda for event logging, and appears to meet our needs (subject to further analysis). Once we've defined one or more streams, it's very easy to start creating instruments in JavaScript and/or PHP code.
No schema creation is needed; MP relies on a predefined "monoschema".
The essential requirement for defining an MP stream is to determine which of the predefined "contextual values" should be added to the stream's events, by MP. (Note: In addition to these contextual values, event-specific "custom values" can be specified by each instrument. These custom values are //not// mentioned in the stream's definition.)
Once these contextual values have been determined, and a stream name chosen, the stream can be declared in [[ https://gerrit.wikimedia.org/r/plugins/gitiles/operations/mediawiki-config/%2B/master/wmf-config/ext-EventStreamConfig.php | ext-EventStreamConfig.php]], for production and beta, or in [[ https://gerrit.wikimedia.org/r/plugins/gitiles/operations/mediawiki-config/%2B/master/wmf-config/InitialiseSettings-labs.php | InitialiseSettings-labs.php]], for beta only.
Relevant documentation is at [[ https://wikitech.wikimedia.org/wiki/Metrics_Platform/Creating_a_Stream_Configuration | Metrics_Platform/Creating_a_Stream_Configuration ]] and related pages. Example MP stream definitions can be found in [[ https://gerrit.wikimedia.org/r/plugins/gitiles/operations/mediawiki-config/%2B/master/wmf-config/ext-EventStreamConfig.php | ext-EventStreamConfig.php]], by searching for `metrics_platform_client`.
**Desired behavior/Acceptance criteria**
* Once instrument(s) for the stream have been created, their behavior should be consistent with what's described at [[ https://wikitech.wikimedia.org/wiki/Event_Platform/Instrumentation_How_To#Viewing_and_querying_events | Event_Platform/Instrumentation_How_To#Viewing_and_querying_events]]
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## Completion checklist
* [ ] Before closing this task, review one by one the checklist available here: https://www.mediawiki.org/wiki/Abstract_Wikipedia_team/Definition_of_Done#Front-end_Task/Bug_Completion_Checklist