Problem

Dev Container Features declare security options (privileged, init, capAdd, securityOpt) and entrypoint scripts in their metadata. For image/Dockerfile devcontainers these become docker run flags; the reference devcontainers/cli also applies them to docker-compose services via its generated override compose file (generateFeaturesComposeOverrideContent).

Our compose path merged the metadata into ResolvedConfig but never carried it onto the service. So a feature like docker-in-docker silently failed on compose-source devcontainers:

• the container came up unprivileged, and
• the feature's docker-init.sh entrypoint never ran,

…so docker inside the container reported the daemon was down. This was hit in real use on the DAP devcontainer (prebuilt image carrying dind in its devcontainer.metadata label).

Fix

Security options

• Extend compose.Override with Privileged/Init/CapAdd/SecurityOpt; build it once from cfg in createFreshCompose and apply on both backends — ApplyRunOverride (native, in-memory project mutate) and WriteRunOverride (shellout YAML).
• serviceToRunSpec now forwards Privileged/SecurityOpt to RunSpec (Init/CapAdd were already mapped).

Entrypoint chaining

• Aggregate the metadata entrypoint chain into ResolvedConfig.Entrypoints (base-image label entries first, then features; idempotent).
• RenderEntrypointWrapper builds the /bin/sh -c '<each entrypoint>; exec "$@"' wrapper that runs feature entrypoints before the original entrypoint+command. Native path emits a single $; shellout path doubles to $$ because docker compose re-interpolates the written YAML.
• Add ImageDetails.Entrypoint (+ docker InspectImage) so a non-null image ENTRYPOINT is preserved underneath the wrapper.

Inspect contract

• ContainerDetails gains Privileged/CapAdd/SecurityOpt, read from HostConfig in docker InspectContainer (reused by the podman backend), so tests can verify what actually landed on the container. Applecontainer can't surface these (VM isolation) — left at zero values.

Testing

• Unit: wrapper rendering (escaped vs native $), override apply + YAML emit, and metadata aggregation/idempotency.
• Integration (TestComposeSource_FeatureSecurityOptionsApplied): brings up a compose devcontainer whose feature declares privileged/init/capAdd/securityOpt and an entrypoint, then asserts all of them land on the real container via inspect + that the entrypoint marker ran. Green on both native and shellout backends.
• Verified end-to-end against the real DAP devcontainer: dockerd now starts.

Scope / follow-up

Image-source (non-compose) entrypoint chaining is intentionally not included — newRunSpec doesn't consume cfg.Entrypoints yet because the interaction with OverrideCommand/keep-alive is delicate. The reported case (compose) is fully covered. Tracked as a follow-up.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Feature entrypoints can now be chained and wrapped so they run before the original container entrypoint/command.
  • Compose run overrides can now set and preserve security settings (privileged/init, additional capabilities, security options).

• Bug Fixes

  • Security metadata is merged additively with stable deduplication (no duplicate capabilities/options).
  • Security and entrypoint details are now more accurately propagated into runtime inspection/output.

• Tests

  • Expanded unit and integration coverage for entrypoint chaining, security option application, compose backends (native/shellout), and metadata merge/idempotency.