Tilt: Support for podman instead of docker

[monester]

Latest version of Docker doesn't work on Fedora 31 because of missing cgroupsv2 support. Can you add support for alternative container runtimes - for example podman.

[jgillich]

FYI, Docker works when you boot with systemd.unified_cgroup_hierarchy=0. Still +1 from me.

[landism]

Can you add support for alternative container runtimes - for example podman.

Just to be sure I understand, is the issue with the container runtime or the image builder? (it's common to conflate the two since they often come as one package)

For the image builder, tilt supports non-docker image builders via custom_build.

For the container runtime, I believe as long as you're not using restart_container with live_update, the container runtime does not matter to Tilt. (and if you want to use restart_container with a non-docker runtime, there's rerun-process-wrapper as a workaround.

[jgillich]

I think this is about image building, so the relevant tool is buildah.

I still have a lot of confusion around registries, but custom_build does not seem to be a full replacement because Tilt still assumes the result is an image stored in Docker. You could do disable_push=True, but it seems like Tilt has some mechanisms built in to override a remote registry with a in-cluster registry (or does it?), so doing a push via buildah would break that.

Besides, I think there's still some value in supporting buildah natively. When you work in a team and people are using different platforms, not everyone will be using the same container builder/runtime. podman/buildah do not require a daemon or even root access, that's why they're seeing more and more adoption.

[nicks]

let me poke at this a bit and write docs on how to do it.

ideally, i'd want custom_build to be powerful enough that you could implement docker_build as just a thin wrapper around custom_build. And then there'd be a bunch of off-the-shelf Tiltfile functions for how to use custom builds that you could load() or copy-and-paste.

custom_build should be smart enough to handle in-cluster registries correctly but i'll check that too

[monester]

@nicks thanks! amazing job! I'm going to test it now.

[nicks]

we actually needed to do some fixes on the Tilt side, which will be available in the next release. I'm also going to add a bit to our custom_build guide, but for reference, here's a demo Tiltfile where i got it working:

https://github.com/windmilleng/tilt-frontend-demo/blob/nicks/buildah/Tiltfile

[monester]

can't test as I can't build binary :-(

# make all
....
FAIL
FAIL    github.com/windmilleng/tilt/internal/tiltfile   13.045s
ok      github.com/windmilleng/tilt/internal/tiltfile/analytics (cached)
ok      github.com/windmilleng/tilt/internal/tiltfile/dockerprune   (cached)
ok      github.com/windmilleng/tilt/internal/tiltfile/flags (cached)
ok      github.com/windmilleng/tilt/internal/tiltfile/git   (cached)
ok      github.com/windmilleng/tilt/internal/tiltfile/include   (cached)
?       github.com/windmilleng/tilt/internal/tiltfile/io    [no test files]
ok      github.com/windmilleng/tilt/internal/tiltfile/k8scontext    (cached)
ok      github.com/windmilleng/tilt/internal/tiltfile/os    (cached)
ok      github.com/windmilleng/tilt/internal/tiltfile/starkit   (cached)
?       github.com/windmilleng/tilt/internal/tiltfile/value [no test files]
ok      github.com/windmilleng/tilt/internal/tiltfile/version   (cached)
ok      github.com/windmilleng/tilt/internal/token  (cached)
ok      github.com/windmilleng/tilt/internal/tracer (cached)
ok      github.com/windmilleng/tilt/internal/watch  (cached)
ok      github.com/windmilleng/tilt/internal/yaml   (cached)
ok      github.com/windmilleng/tilt/pkg/assets  (cached)
ok      github.com/windmilleng/tilt/pkg/logger  (cached)
ok      github.com/windmilleng/tilt/pkg/model   (cached)
?       github.com/windmilleng/tilt/pkg/webview [no test files]
?       github.com/windmilleng/tilt/tools/devlog    [no test files]
?       github.com/windmilleng/tilt/web [no test files]
FAIL
make: *** [Makefile:58: test-go] Error 1

Will wait until next release.

[nicks]

OK, v0.10.22 should have a new argument to custom_build called skips_local_docker=True that skips the image check so you can use buildah. I've updated the branch with more details:
https://github.com/windmilleng/tilt-frontend-demo/blob/nicks/buildah/Tiltfile

[nicks]

Added some documentation to the custom_build guide on how to use buildah:
https://docs.tilt.dev/custom_build.html