Using buildah inside a RHEL container

using-buildah-inside-a-rhel-container.md

Why

• Unlike Docker, buildah doesn't need root privileges to run
• Buildah can pass yum entitlements from build container to container being built
  • Since this has to be done manually (see /run/secrets:/run/secrets below) couldn't Docker do this as well?

Steps

1. Make sure you're using a RHEL host registered with yum

2. Make sure you're using RHEL build container image, such as:

   • registry.access.redhat.com/ubi7/ubi
   • registry.access.redhat.com/rhel7

3. Install buildah in the build container

   # Override the default buildah storage driver; fixes "'overlay' is not supported over overlayfs" error
   export STORAGE_DRIVER=vfs
   # This is needed so that the yum entitlements from the build container end up in the container being built
   mkdir -p /etc/containers/; echo "/run/secrets:/run/secrets" >> /etc/containers/mounts.conf
   yum install -y --enablerepo=rhel-7-server-extras-rpms buildah

4. Build the image using buildah

   buildah bud ...