mkctr is a small go binary which uses GOOS= GOARCH= go build directly to compile go binaries and then uses go-containerregistry to create and publish the new containers based on the desired platforms.

This is inspired by ko which is awesome but doesn't support multiple binaries in a single container.

mkctr \
  --base="alpine:latest" \
  --gopaths="\
    tailscale.com/cmd/tailscale:/usr/local/bin/tailscale, \
    tailscale.com/cmd/tailscaled:/usr/local/bin/tailscaled" \
  --tags="latest" \
  --repos="tailscale/tailscale" \
  [--files=foo.txt:/var/lib/foo.txt,bar.txt:/var/lib/bar.txt] \
  [--target=<target>] \ # e.g. flyio, local
  [--push] \
  [--] [<cmd>...]

mkctr auto discovers GOOS/GOARCH from the specified base image. If the base image supports multiple platforms, binaries are compiled for each platform as long as it's one of linux/amd64, linux/386, linux/arm, linux/arm64. Multi-arch base image must be either an OCI image index or Docker manifest list. mkctr produces image of the same media type as the base image and uses the media type of the base image, or of the individual image references in case of a multi-arch image, to determine the media type of the layer it builds.

This is under active development. While Tailscale uses it, backwards compatability is not guaranteed, and some functionality is missing.