fix: detect container ID when /var/lib/docker is a separate mount#747
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buchdag merged 1 commit intoJun 28, 2026
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Pull request overview
This PR fixes .Docker.CurrentContainerID detection when /var/lib/docker (or /var/lib/docker/containers) is mounted separately, causing mountinfo paths to appear as /<id>/hosts without a containers/ segment and previously resulting in an empty container ID.
Changes:
- Updates mountinfo parsing to anchor the container ID match to known per-container files (
hostname,hosts,resolv.conf) instead of requiring a literalcontainers/path segment. - Adds a regression test covering the “separate mount” mountinfo layout from issue #452.
Reviewed changes
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| File | Description |
|---|---|
| internal/context/context.go | Adjusts mountinfo-specific regex to match container IDs via /<id>/(hostname|hosts|resolv.conf) so separate-mount layouts are detected. |
| internal/context/context_test.go | Adds TestGetCurrentContainerIDSeparateMount to validate detection when per-container files appear under /<id>/... paths. |
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Jun 28, 2026
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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GetCurrentContainerIDreads/proc/<pid>/mountinfoand, on a mountinfo line, anchored the container-id match to a literalcontainers/path segment. When/var/lib/docker/containers(or/var/lib/docker) is its own mount, the per-container files appear as/<id>/hostswith nocontainers/segment, so detection returned empty and.Docker.CurrentContainerIDwas blank — breaking templates that rely on it (e.g. nginx-proxy, causing 502s).This anchors the id to a known per-container file instead (
/<id>/(hostname|hosts|resolv.conf)), matching both the default layout (/var/lib/docker/containers/<id>/hosts) and a separate-mount layout (/<id>/hosts), while still excluding the overlay2 layer hashes in the mount options. The cpuset/cgroup paths are unaffected.Adds
TestGetCurrentContainerIDSeparateMount; the existing #355 mountinfo test still passes.Fixes #452
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