This updates the `template` subcommand to be `generate`. The `template`
usage will continue to work as an alias to `generate`. A new `switch`
command is added that will manage both `rpm-ostree rebase` and
`rpm-ostree upgrade` and is fully replacing the respective subcommands
as a breaking change.
The new `switch` command is under the feature flag `switch` and will
currently only build for the `main` branch builds until it is moved as a
default feature (`v0.9.0`).
Closes#159
### Buildah/Podman support
Buildah and podman can make heavy use of the squash feature. Something
that I've noticed when trying to build from inside of a container,
requiring intermediate layers with mounts causes build times to
skyrocket. Build times are much faster when using the `--squash`
functionality (seen as `--layers=false`).
Here are the following results from my personal build using both squash
and non-squash functionality.
#### Squash upgrade:
```
$> rpm-ostree upgrade
Pulling manifest: ostree-image-signed:docker://registry.gitlab.com/wunker-bunker/wunker-os/jp-laptop
Importing: ostree-image-signed:docker://registry.gitlab.com/wunker-bunker/wunker-os/jp-laptop (digest: sha256:60f743ba322041918d302e7e7f10438c59502e19343c294064bacb676c8eb7b7)
ostree chunk layers already present: 65
custom layers already present: 3
custom layers needed: 1 (814.0 MB)
```
All changes appear to show as a single custom layer. Any small change
even at the end of the build appears to require completely downloading
the new layer (squash only squashes additional layers on top of the base
layer). This makes sense as layers cannot currently be downloaded by
diff.
#### Non-squash upgrade:
```
$> rpm-ostree upgrade
Pulling manifest: ostree-image-signed:docker://registry.gitlab.com/wunker-bunker/wunker-os/jp-desktop-gaming:latest
Importing: ostree-image-signed:docker://registry.gitlab.com/wunker-bunker/wunker-os/jp-desktop-gaming:latest (digest: sha256:0658b51febfcbaa1722961b7a6d2b197d3823a6228e330f45dd1e1aaefd145c5)
ostree chunk layers already present: 65
custom layers already present: 4
custom layers needed: 15 (942.4 MB)
```
As expected, there are more layers when not squashing and the size is
slightly bigger. Most likely due to there being extra information stored
in the layers that is subsequently removed.
### Docker support
Docker is apparently [no longer
supporting](https://github.com/docker/buildx/issues/1287) the use of the
`--squash` arg. The use of squash will not be available for the docker
driver in this case.
All supported versions of podman, buildah, and docker support the zstd
compression format. This format should allow users to pull less data
when updating their computers.
This fix involves creating a new function for the `BuildDriver` trait
called `build_tag_push`. In order to get the proper logic in place to
make use of `docker buildx`, I had to create a separate function that
would construct the build command to include all of the tags necessary
for pushing. A default implementation of `build_tag_push` will be used
for `podman` and `buildah` which was originally from the build command's
functions. Now that we have custom logic for docker builds, we can take
advantage of using the GitHub cache features without having the `--load`
arg which had a big negative effect on build times. We can now also use
docker for creating local `oci-archive` tarballs for local rebasing.
Making use of the `oci-archive` will require the user to create a
`docker-container` builder as it is not supported on the standard
`docker` builder.
https://docs.docker.com/build/exporters/oci-docker/
