Add injectionMode option for APM instrumentation

[iamluc]

What this PR does / why we need it:

This PR adds a new datadog.apm.instrumentation.injectionMode option to configure how tracing libraries are injected into application pods.

Supported modes:

• auto (default): Automatically selects the best injection method
• init_container: Uses init containers to inject libraries
• csi: Uses the Datadog CSI Driver to inject libraries (experimental)

The CSI injection mode is experimental and requires Cluster Agent 7.76.0+ with the Datadog CSI Driver installed.

Changes:

• Add injectionMode option in values.yaml with default value "auto"
• Pass DD_APM_INSTRUMENTATION_INJECTION_MODE env var to Cluster Agent when set
• Update values.schema.json with the new field and allowed values

Related PRs:

• Cluster Agent implementation: feat(ssi): add config option to set the injection mode datadog-agent#45211

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• All commits are signed (see: signing commits)
• Chart Version semver bump label has been added (use <chartName>/minor-version, <chartName>/patch-version, or <chartName>/no-version-bump)
• For datadog or datadog-operator chart or value changes, update the test baselines (run: make update-test-baselines)

GitHub CI takes care of the below, but are still required:

• Documentation has been updated with helm-docs (run: .github/helm-docs.sh)
• CHANGELOG.md has been updated
• Variables are documented in the README.md

[Mathew-Estafanous]

Everything looks good.

One ask. Can you add a check in NOTES.txt that warns or errors when datadog.apm.instrumentation.injectMode is set to csi without datadog.csi.enabled set to true?

I think that should prevent customers attempting to use CSI injection without first setting up the driver itself.

[betterengineering]

👌

[iamluc]

/merge

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2026-01-26 14:01:24 UTC ℹ️ Start processing command /merge

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