Symlink on /var/lib/postgresql/data points to itself for the pg18 image

[tiemma]

In executing the docker image in Kubernetes via volume mounts, the folder under the points to itself.

How to reproduce

docker run -it timescale/timescaledb:latest-pg18 bash
1b6828e06f2b:/# ls -l /var/lib/postgresql/data
lrwxrwxrwx    1 root     root             1 Oct 22 17:43 /var/lib/postgresql/data -> .

I also tested with file. The path linking to . causes a recursive symlink preventing any mountpoints from working.

1b6828e06f2b:/# apk add file
fetch https://dl-cdn.alpinelinux.org/alpine/v3.21/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.21/community/x86_64/APKINDEX.tar.gz
(1/2) Installing libmagic (5.46-r2)
(2/2) Installing file (5.46-r2)
Executing busybox-1.37.0-r13.trigger
OK: 216 MiB in 49 packages
1b6828e06f2b:/# file /var/lib/postgresql/data
/var/lib/postgresql/data: symbolic link to .


# From here, notice the recursive directory symlink

1b6828e06f2b:/# file /var/lib/postgresql/data/data/
/var/lib/postgresql/data/data/: sticky, directory
1b6828e06f2b:/# file /var/lib/postgresql/data/data
/var/lib/postgresql/data/data: symbolic link to .
1b6828e06f2b:/# file /var/lib/postgresql/data/data/data
/var/lib/postgresql/data/data/data: symbolic link to .

This issue breaks usage from the container runtime as a valid mountpoint

failed to create containerd task: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error mounting "/var/lib/kubelet/pods/839353ec-7453-4aed-8846-719ed4456498/volumes/kubernetes.io~csi/pvc-d155d89c-6fd9-4446-a30f-4081ed2f64bb/mount" to rootfs at "/var/lib/postgresql/data": change mount propagation through procfd: open o_path procfd: open /run/containerd/io.containerd.runtime.v2.task/k8s.io/43d63a4d42ccf97fc981274375887dc23fb4fae236ee0e702ca5e263515a62d9/rootfs/var/lib/postgresql/data: no such file or directory: unknown

Fix

The solution should be un-linking the directory from the postgres image and creating it again, I did not see anything asides the builds added in the pg18 Dockerfile updates so there might be more to look at than the mitigating suggestion.

[svenklemm]

This was introduced by upstream so you should probably report this issue there:

%  docker run -ti --rm postgres:18-alpine bash
4376b4cbfbfb:/# ls -la /var/lib/postgresql/data
lrwxrwxrwx    1 root     root             1 Oct 22 17:42 /var/lib/postgresql/data -> .
4376b4cbfbfb:/#

[tiemma]

PR to fix this was made last October 15: docker-library/postgres#1372 (comment)