PMM-15071: Add MongoDB Unused Indexes dashboard

[fabio-silva]

Summary

Adds a new MongoDB Unused Indexes Grafana dashboard that surfaces indexes with zero accesses since the last mongod restart — candidates for review and possible removal.

The dashboard uses the same core metric and logic as the existing MongoDB Unused Indexes advisor check:

avg by (cluster, collection, database, key_name) (
  mongodb_indexstats_accesses_ops{node_name=~"$node_name"}
) == 0

Changes

• New dashboard: dashboards/dashboards/MongoDB/MongoDB_Unused_Indexes.json
  • Summary stats: instance uptime, unused index count, total indexes monitored
  • Table panel listing unused indexes by cluster/database/collection/index
  • Timeseries and table panels for index access activity
  • Standard MongoDB dashboard variables (environment, cluster, replication set, service, database)
  • Excludes the default _id_ index
• Plugin registration: added to dashboards/pmm-app/src/plugin.json
• PMM UI navigation: added under MongoDB → Unused indexes
• Documentation: documentation/docs/reference/dashboards/dashboard-mongodb-unused-indexes.md

Requirements

The indexstats collector must be enabled on the MongoDB exporter for this dashboard to show data.

Notes

• Index usage is recorded only on the node that executes the query; on replica sets, review all members before dropping an index.
• Screenshots can be added in a follow-up once validated against a live PMM environment.

Screenshots

Ticket number: PMM-15071

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.88%. Comparing base (31318c7) to head (d4bad9e).
⚠️ Report is 42 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5636      +/-   ##
==========================================
+ Coverage   43.59%   43.88%   +0.28%     
==========================================
  Files         415      545     +130     
  Lines       43134    44426    +1292     
  Branches        0      591     +591     
==========================================
+ Hits        18804    19495     +691     
- Misses      22454    23099     +645     
+ Partials     1876     1832      -44     

Flag	Coverage Δ
admin	34.96% <ø> (+0.17%)	⬆️
unittests	41.29% <ø> (?)

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[Copilot]

Pull request overview

Adds a new Grafana dashboard to help identify MongoDB indexes with zero accesses since the last mongod restart, and wires it into PMM UI navigation, the dashboards plugin bundle, and the documentation site.

Changes:

• Introduces the MongoDB Unused Indexes dashboard (panels + variables + PromQL) based on mongodb_indexstats_accesses_ops.
• Registers the dashboard in the Grafana plugin bundle and adds a MongoDB navigation entry in PMM UI.
• Adds a new dashboard documentation page and links it in MkDocs navigation.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
ui/apps/pmm/src/contexts/navigation/navigation.constants.ts	Adds a MongoDB navigation item pointing to the new dashboard.
dashboards/dashboards/MongoDB/MongoDB_Unused_Indexes.json	New Grafana dashboard definition (panels, variables, queries).
dashboards/pmm-app/src/plugin.json	Registers the new dashboard so it’s shipped with the PMM Grafana plugin.
dashboards/README.md	Updates featured dashboards list to include the new dashboard.
documentation/docs/reference/dashboards/dashboard-mongodb-unused-indexes.md	Adds documentation for the new dashboard.
documentation/mkdocs-base.yml	Adds the new doc page to the MkDocs nav tree.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.