3.2. Creating logically bound images

Procedure

1. Select the image that you want to logically bound.

2. Create a Containerfile:

   $ cat Containerfile
   FROM quay.io/<namespace>/<image>:latest
   COPY ./<app_1>.image /usr/share/containers/systemd/<app_1>.image
   COPY ./<app_2>.container /usr/share/containers/systemd/<app_2>.container
   
   RUN ln -s /usr/share/containers/systemd/<app_1>.image \
   	/usr/lib/bootc/bound-images.d/<app_1>.image && \
       ln -s /usr/share/containers/systemd/<app_2>.container \
       	/usr/lib/bootc/bound-images.d/<app_2>.container

3. In the .container definition, use:

   GlobalArgs=--storage-opt=additionalimagestore=/usr/lib/bootc/storage

   In the Containerfile example, the image is selected to be logically bound by creating a symlink in the /usr/lib/bootc/bound-images.d directory pointing to either an .image or a .container file.

4. Run the bootc upgrade command.

   $ bootc upgrade

   The bootc upgrade performs the following overall steps:

   1. Fetches the new base image from the image repository. See Configuring container pull secrets.
   2. Reads the new base image root file system to discover logically bound images.
   3. Automatically pulls any discovered logically bound images defined in the new bootc image into the bootc-owned /usr/lib/bootc/storage image storage.

5. Make the bound images become available to container runtimes such as Podman. For that, you must explicitly configure bound images to point to the bootc storage as an "additional image store". For example:

   podman --storage-opt=additionalimagestore=/usr/lib/bootc/storage run <image>