[cvas22]

I added nerdctl compose stats, one of the Compose commands still listed as unimplemented in the command reference (tracked in #3867).

It follows docker compose stats:

• nerdctl compose stats [SERVICE...] shows the live resource usage of the project's containers, or only those of the given services.
• -a/--all, --format, --no-stream and --no-trunc work as in nerdctl stats.
• By default only running containers are shown; --all includes stopped ones.

The command collects the project's container IDs and hands them to the existing container.Stats, the same way compose top reuses container.Top, so the output and formats are identical to nerdctl stats. When the project has no matching containers it returns right away, because container.Stats with no IDs would show every container on the host.

Changes:

• cmd/nerdctl/compose/compose_stats.go: the command
• cmd/nerdctl/compose/compose_stats_linux_test.go: tests for all services, one service, and a stopped service skipped by default
• docs/command-reference.md: documented the command and removed it from the unimplemented list

Notes

I ran TestComposeStats locally as root in a privileged container, with containerd and buildkitd from the out-full build and nerdctl built from this branch:

--- PASS: TestComposeStats (29.40s)
    --- PASS: TestComposeStats/all_services (1.05s)
    --- PASS: TestComposeStats/one_service (1.05s)
    --- PASS: TestComposeStats/stopped_service_is_skipped (10.24s)

golangci-lint (the version pinned in the Makefile) reports 0 issues for ./cmd/nerdctl/compose/, for both Linux and Windows. I haven't tried rootless mode.

I also had a subtest for --all with a stopped service. It passed locally, where containerd v2 runs rootful, but in CI it timed out after 3 minutes on the containerd v1.7.36 and rootless jobs (stats --all --no-stream ... svc1 never returned). compose stats passes the container IDs to the same container.Stats that nerdctl stats uses, and nothing tests nerdctl stats --no-stream on a stopped container, so I suspect the same hang with nerdctl stats --no-stream <stopped container> on those setups. I haven't confirmed that. I removed that subtest from this PR instead of guessing at a fix in container.Stats, and I'm happy to look into it separately if you'd like.

[cvas22]

The failing jobs aren't failing in TestComposeStats. build failed downloading a module from the Go proxy (INTERNAL_ERROR on google.golang.org/grpc). The almalinux-8 jobs fail in unrelated tests (TestRunContainerWithStaticIP6, TestVolumeRemove, TestWait), and kubernetes in TestKubeCommitSave. I don't have permission to re-run the jobs, so could a maintainer re-run the failed ones?

[cvas22]

Same fix as in #5325: compose stats now releases the global compose lock before streaming (4ee788c), like compose logs does since #3678. Without --no-stream it runs until interrupted, so holding the lock blocked every other compose command in the meantime.