Alpine Docker VM Fails to Start Due to `/etc/hosts` Move Operation Error

[Manu-bytes]

Summary

When attempting to run an Alpine Linux Docker container as a GNS3 Docker VM node, the startup sequence fails because the GNS3 server attempts to modify the container's /etc/hosts file using an operation that involves moving/renaming, which is blocked as /etc/hosts is mounted as a tmpfs volume by Docker.

Environment

• GNS3 Version: GNS3 3.0.5 (GUI and Server)
• Operating System (GNS3 Server): [Arch Linux 6.17.9]
• Podman Version: [5.7.0]
• Docker Image Used: alpine:latest

Steps to Reproduce

1. Create a new project in GNS3 3.0.5.
2. Add a Docker VM node using the Alpine Linux image.
3. Set the Start Command for the node to a simple shell: sh or /bin/sh.
4. Start the node.

Expected Behavior

The Alpine container should start successfully, execute the /bin/sh command, and be ready to use (e.g., allowing console access).

Actual Behavior (Error)

The node fails to start, and the GNS3 server logs display an error indicating that the move/rename operation on /etc/hosts failed because the resource is busy.

GNS3 Server Log Output:

2025-12-03 17:23:25 ERROR gns3server.compute.docker.docker_vm:637 sed: can't move '/etc/hostsiBgJfa' to '/etc/hosts': Resource busy
2025-12-03 17:23:25 ERROR gns3server.compute.docker.docker_vm:637 / # 
2025-12-03 17:23:25 ERROR gns3server.api.routes.compute:133 Compute node error: sed: can't move '/etc/hostsiBgJfa' to '/etc/hosts': Resource busy

Container File System State (Observed inside the container):

The /etc/hosts file is mounted as a tmpfs volume:

/ # mount | grep /etc/hosts
run on /etc/hosts type tmpfs (rw,nosuid,nodev,relatime,mode=755,inode64)

Is there a way to fix this behavior?