Add support for running bootc bootable containers #54
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This was referenced May 8, 2024
Signed-off-by: Alberto Faria <[email protected]>
We attempt to detect if a container image is bootable. We can't easily retrieve the image's labels, so we check if /usr/lib/bootc/install exists and is a directory. If so, it is a bootable container. If it is a bootable container but we're not running under Podman, we fail with an error. Once our container's entrypoint starts running, a background process on the host (outside the container) queries Podman for the image's name and ID, which the OCI runtime does not get but bootc-install needs. It then saves the container image as an OCI archive. It then runs the original container to generate the VM image. We do this using krun [1] so that elevated privileges aren't necessary. Our entrypoint blocks until this is done, and all subsequent logic remains the same. We could potentially avoid the OCI archive creation step by mounting the host's container storage into the container running under krun. This isn't trivial to achieve due to SELinux label and context mismatches between the host and the krun environment, so we leave this optimization for a future date. Closes #26. [1] https://github.com/containers/crun/blob/main/krun.1.md Signed-off-by: Alberto Faria <[email protected]>
Store them as untagged containerdisks in the user's container storage. They appear in the output of `podman images`, making users aware of their existence and size on disk, and cleanup commands like `podman image prune` remove them. Signed-off-by: Alberto Faria <[email protected]>
Signed-off-by: Alberto Faria <[email protected]>
Signed-off-by: Alberto Faria <[email protected]>
It allows settings the disk size of the VM image that is generated from a bootc container image. Also improve the default disk size by basing it on the container image size. Signed-off-by: Alberto Faria <[email protected]>
Its value is a random identifier unique to the current run of the current test. Signed-off-by: Alberto Faria <[email protected]>
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We attempt to detect if a container image is bootable. We can't easily retrieve the image's labels, so we instead look for files under /usr/lib/bootc/install. If there are none, it isn't a bootable container. If it is a bootable container but we're not running under Podman or Docker, we fail with an error.
Once our container's entrypoint starts running, a background process on the host (outside the container) queries Podman/Docker for the image's name and ID, which the OCI runtime does not get but bootc-install needs. It then saves the container image as a docker-archive.
It then runs the original container to generate the VM image. We do this using krun so that elevated privileges aren't necessary. Our entrypoint blocks until this is done, and all subsequent logic remains the same.
We could potentially avoid the docker-archive creation step by mounting the host's container storage into the container running under krun. This isn't trivial to achieve due to SELinux label and context mismatches between the host and the krun environment, so we leave this optimization for a future date.
Closes #26.
TODO: