I'm running Docker as root inside an Alpine Linux LXC container on Proxmox. The container hosts NPMPlus, and I'm trying to pull the TecharoHQ Anubis image either through Compose or directly with `docker pull ghcr.io/techarohq/anubis:latest`. Both methods fail while extracting an overlayfs layer with an error like: `failed to extract layer ... mount callback failed ... operation not permitted`. The host is using Docker 29.5.3 with the overlayfs storage driver and containerd snapshotter, on Alpine Linux 3.24 with kernel 7.0.0-3-pve. Docker is running as root, and the system has about 4 GiB of memory. Rebooting several times didn't help, although the image works on another device. Could this be caused by disk space, LXC restrictions, overlayfs, or something else in the Docker/Proxmox setup?
3 Answers
This looks more like an environment or storage problem than an issue with the Anubis image itself. The failure happens when containerd tries to mount the temporary layer using overlayfs, and an LXC container can be restricted from performing the required mount operation. Check the LXC features and nesting settings on the Proxmox host, along with Docker’s storage-driver compatibility. Also verify that the filesystem backing `/var/lib/docker` supports overlayfs and that the container has enough free disk space and inodes.
The image author also noted that this isn’t a commonly reported Anubis-specific error. Rebooting is a reasonable first test, but repeated failures after reboot suggest checking the host-level LXC configuration, especially nesting, keyctl, and mount-related restrictions. You may need to adjust the container privileges or use a Docker storage setup supported by nested containers rather than changing the Compose file.
It’s worth checking disk space, inode usage, and the Docker data directory directly. A full filesystem can sometimes produce confusing layer-extraction errors, although the explicit `operation not permitted` message points more strongly toward an overlayfs or LXC permission restriction. Since the same image pulls successfully elsewhere, compare the Proxmox container configuration and the filesystem used for `/var/lib/docker` between the two systems.
I rebooted several times because I initially suspected a transient memory or kernel issue, but the error stayed the same. For now I’m running Anubis on another device, where the pull works normally.