Docker
Docker rootless mode failed because max_user_namespaces is too small
[rootlesskit:parent] error: failed to start the child: fork/exec /proc/self/exe: no space left on device
Rootless Docker could not start because the system limit for user namespaces is too low for the rootless setup.
Observed message
[rootlesskit:parent] error: failed to start the child: fork/exec /proc/self/exe: no space left on device
Why it happens
- The value of /proc/sys/user/max_user_namespaces is too small.
- The host does not allow enough user namespaces for rootless Docker.
How to fix it
- Set user.max_user_namespaces to a larger value such as the Docker-documented recommendation.
- Apply the sysctl change and retry the rootless Docker startup.
