Notes from a 3 AM On-Call: Docker Daemon Socket Permission Denials That Survive Group Membership

The Failure Symptom

$ docker ps Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post "http://%2Fvar%2Frun%2Fdocker.sock/v1.47/containers/json": dial unix /var/run/docker.sock: connect: permission denied

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Standard response: add user to docker group. Already done. Still fails. groups output shows docker . ls -l /var/run/docker.sock shows srw-rw---- 1 root docker . Everything looks correct.

Three deploys failed in a row because our ephemeral CI runners couldn't talk to the Docker daemon after provisioning.…