Configuration for rootless podman and buildah

There is special k8s node configuration required for running rootless podman or buildah in a Gitlab CI pipeline. You will see an error like this

cannot clone: Invalid argument
user namespaces are not enabled in /proc/sys/user/max_user_namespaces
Error: Cannot connect to the Podman socket, make sure there is a Podman REST API service running.

On nodes where gitlab-runners execute user.max_user_namespaces must be set.

sysctl user.max_user_namespaces=28633

Here is an example of an Ansible script

- name: Configure sysctl on gitlab-runner nodes to allow rootless podman builds
  hosts: all
  become: yes
  tasks:
  - name: Enable user namespaces
    sysctl:
      name: user.max_user_namespaces
      value: 28633
      state: present
      reload: yes
      sysctl_set: yes
    when: node_pool == "gitlab-runner"

Example pipeline scripts. You will need to pass a storage-diver argument

buildah bud --format=docker --storage-driver=vfs "${IMAGE_TAG}" .

buildah tag --storage-driver=vfs "${IMAGE_REGISTRY_REPO}" "${IMAGE_FULLTAG}"

buildah push --storage-driver=vfs --authfile staging_auth.json --digestfile="${ARTIFACT_DIR}/digest" "${IMAGE_FULLTAG}"