feat(osd): enable SQL in Explore, query profiling, PPL alerting, and 3.9 Explore/dashboard flags

[ps48]

Description

OSD 3.8 and 3.9 added several observability features that ship off by default. This turns them on so the stack exposes them out of the box.

Chart + docker-compose (safe on the 3.8 images the chart currently pins):

• explore.sqlSupport (3.8) — SQL alongside PPL in the Explore query language picker, incl. the Patterns tab for SQL
• explore.queryProfiling (3.8) — warns when saving a complex, resource-heavy query as a visualization
• opensearch_alerting.pplAlertingEnabled — surfaces Create alert rule in Explore logs (docker-compose already set this; the chart did not)

docker-compose only (3.9-only keys; the chart follows with the 3.9 image bump):

• explore.pplAnalyze (3.9) — Analyze panel: query phase timeline, operator waterfall, recommendations
• dashboard.allowDashboardSections (3.9) — collapsible dashboard sections

OSD rejects unknown config keys at startup, so a 3.9-only key in the chart would break Dashboards on a 3.8 image. Verified below.

Testing

• ./test/helm-test.sh — helm lint + 73 unit tests across 12 suites pass.
• Booted the rendered OSD config in real containers:
  • rendered chart config (values + values-anonymous-auth) on opensearchproject/opensearch-dashboards:3.8.0 → starts clean
  • same config on 3.9 → starts clean
  • docker-compose template (all 5 flags) on 3.9 → starts clean
  • negative control: chart config + explore.pplAnalyze.enabled on 3.8 → FATAL ValidationError: [config validation of [explore].pplAnalyze]: definition for this key is missing. This is why the 3.9 keys are docker-only for now.
• Flag availability per version confirmed against release tags: sqlSupport/queryProfiling exist in OSD 3.8.0 and 3.9.0; pplAnalyze/allowDashboardSections only in 3.9.0; pplAlertingEnabled exists in alerting-dashboards 3.7.0.0 and 3.8.0.0.
• Applied the 3.8-safe flags plus the two 3.9 flags to the live playground (now on 3.9): the query language picker offers PPL | SQL, and Create alert rule appears in the Explore logs toolbar.

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[kylehounslow]

AI-assisted review (Claude), checked and posted by me.

Thanks for the negative control on 3.8. It makes the chart vs. compose split easy to trust. I checked the flag schemas against the release tags: sqlSupport/queryProfiling are in explore/common/config.ts on 3.8.0 and 3.9.0, and pplAnalyze and dashboard.allowDashboardSections are only on 3.9.0. Adding pplAlertingEnabled to the chart also closes a real gap with compose.

Approving. Two small comments inline, neither blocking.

[kylehounslow]

AI-assisted review comment.

Heads up that this does more than the description suggests. On 3.9.0 it adds profile: true to every PPL query Explore sends, not just when saving a visualization: query_actions.ts#L857-L859

Probably fine for the playground. However, people copy these values into real deployments, so it's worth knowing what profiling costs per query on the SQL plugin side. Do you have a sense of the overhead, or someone on the SQL team we could ask? Either way, can we update the PR description to say it profiles every PPL query?

[kylehounslow]

AI-assisted review comment.

nit: these two 3.9 keys now exist only in compose, and the chart picking them up depends on someone remembering at the image bump. Could we open a tracking issue, or leave a comment next to tag: "3.8.0" in values.yaml, so the chart doesn't drift from compose?