Tarball output format?

[bioball]

It would be really useful if ko could output images in the tarball format, similar to what you get with docker save. Ideally, ko could output a release.yaml, but output image tarballs rather than publishing them (perhaps writing the tarball to disk?)

Many other tools that build images support outputting docker save-format tarballs; for instance:

• bazel rules_docker
• buildkit
• Kaniko
• img

[jonjohnsonjr]

I think that's pretty reasonable. We had some relevant discussion here: #95

If you wanna work around this today and have docker installed, you could roundtrip it through the daemon, e.g.:

$ ko publish -L ./cmd/ko ./cmd/ko/test | xargs docker save > ko.tar
2020/01/28 13:22:24 Using base gcr.io/distroless/static:latest for github.com/google/ko/cmd/ko
2020/01/28 13:22:24 Building github.com/google/ko/cmd/ko
2020/01/28 13:22:28 Loading ko.local/ko-099ba5bcefdead87f92606265fb99ac0:16cde5ae3bcec10b733f6c8bc81b4c5f2acc0e6e83448994534df6ab2112db83
2020/01/28 13:22:28 Loaded ko.local/ko-099ba5bcefdead87f92606265fb99ac0:16cde5ae3bcec10b733f6c8bc81b4c5f2acc0e6e83448994534df6ab2112db83
2020/01/28 13:22:28 Adding tag latest
2020/01/28 13:22:28 Added tag latest
2020/01/28 13:22:29 Using base gcr.io/distroless/static:latest for github.com/google/ko/cmd/ko/test
2020/01/28 13:22:29 Building github.com/google/ko/cmd/ko/test
2020/01/28 13:22:30 Loading ko.local/test-0e3a563dcfe31cd0109fe43c1bf7c91e:66b8d4278a1d35faf75fcb39e2dc780287d93ce41e1354a87be9fd0947421f89
2020/01/28 13:22:30 Loaded ko.local/test-0e3a563dcfe31cd0109fe43c1bf7c91e:66b8d4278a1d35faf75fcb39e2dc780287d93ce41e1354a87be9fd0947421f89
2020/01/28 13:22:30 Adding tag latest
2020/01/28 13:22:30 Added tag latest

$ tar -tvf ko.tar 
-rw-r--r-- root/root       974 1969-12-31 16:00 083d97e600105c9ada5a70068b19150edc0f08ecdfa5bdfa4bf90b80264174ae.json
drwxr-xr-x root/root         0 1969-12-31 16:00 2f686a0f7524711434ea2e5702c0865e88aceeabf1e48f59fdbb2b395675d117/
-rw-r--r-- root/root         3 1969-12-31 16:00 2f686a0f7524711434ea2e5702c0865e88aceeabf1e48f59fdbb2b395675d117/VERSION
-rw-r--r-- root/root       968 1969-12-31 16:00 2f686a0f7524711434ea2e5702c0865e88aceeabf1e48f59fdbb2b395675d117/json
-rw-r--r-- root/root  44232704 1969-12-31 16:00 2f686a0f7524711434ea2e5702c0865e88aceeabf1e48f59fdbb2b395675d117/layer.tar
drwxr-xr-x root/root         0 1969-12-31 16:00 3b0133856a9c05166c634e5ad85cbb39b15ef093210338060cf900ac28df511e/
-rw-r--r-- root/root         3 1969-12-31 16:00 3b0133856a9c05166c634e5ad85cbb39b15ef093210338060cf900ac28df511e/VERSION
-rw-r--r-- root/root       482 1969-12-31 16:00 3b0133856a9c05166c634e5ad85cbb39b15ef093210338060cf900ac28df511e/json
-rw-r--r-- root/root      1536 1969-12-31 16:00 3b0133856a9c05166c634e5ad85cbb39b15ef093210338060cf900ac28df511e/layer.tar
drwxr-xr-x root/root         0 1969-12-31 16:00 774fa74f98be5577ec663365eef7c24c731c18bde0f1d4a44be8ca50372b076c/
-rw-r--r-- root/root         3 1969-12-31 16:00 774fa74f98be5577ec663365eef7c24c731c18bde0f1d4a44be8ca50372b076c/VERSION
-rw-r--r-- root/root       406 1969-12-31 16:00 774fa74f98be5577ec663365eef7c24c731c18bde0f1d4a44be8ca50372b076c/json
-rw-r--r-- root/root   3061760 1969-12-31 16:00 774fa74f98be5577ec663365eef7c24c731c18bde0f1d4a44be8ca50372b076c/layer.tar
drwxr-xr-x root/root         0 1969-12-31 16:00 a54428111bf69ae5f41b6c2ecd306edc87df992b44486e4ab9a0249cff680e13/
-rw-r--r-- root/root         3 1969-12-31 16:00 a54428111bf69ae5f41b6c2ecd306edc87df992b44486e4ab9a0249cff680e13/VERSION
-rw-r--r-- root/root       482 1969-12-31 16:00 a54428111bf69ae5f41b6c2ecd306edc87df992b44486e4ab9a0249cff680e13/json
-rw-r--r-- root/root     66560 1969-12-31 16:00 a54428111bf69ae5f41b6c2ecd306edc87df992b44486e4ab9a0249cff680e13/layer.tar
-rw-r--r-- root/root       958 1969-12-31 16:00 bb7c25e25ee8280479c454ba42a3a22b1eb7a8678da00898376e98f373a67982.json
drwxr-xr-x root/root         0 1969-12-31 16:00 f4e1da5ab6010d8627624de1f1ccc455d56e415ae596fc03132d7234e85757fe/
-rw-r--r-- root/root         3 1969-12-31 16:00 f4e1da5ab6010d8627624de1f1ccc455d56e415ae596fc03132d7234e85757fe/VERSION
-rw-r--r-- root/root       972 1969-12-31 16:00 f4e1da5ab6010d8627624de1f1ccc455d56e415ae596fc03132d7234e85757fe/json
-rw-r--r-- root/root   2203648 1969-12-31 16:00 f4e1da5ab6010d8627624de1f1ccc455d56e415ae596fc03132d7234e85757fe/layer.tar
-rw-r--r-- root/root       904 1969-12-31 16:00 manifest.json
-rw-r--r-- root/root       370 1969-12-31 16:00 repositories

$ tar -Oxf ko.tar manifest.json | jq .
[
  {
    "Config": "bb7c25e25ee8280479c454ba42a3a22b1eb7a8678da00898376e98f373a67982.json",
    "RepoTags": [
      "ko.local/ko-099ba5bcefdead87f92606265fb99ac0:16cde5ae3bcec10b733f6c8bc81b4c5f2acc0e6e83448994534df6ab2112db83"
    ],
    "Layers": [
      "774fa74f98be5577ec663365eef7c24c731c18bde0f1d4a44be8ca50372b076c/layer.tar",
      "3b0133856a9c05166c634e5ad85cbb39b15ef093210338060cf900ac28df511e/layer.tar",
      "2f686a0f7524711434ea2e5702c0865e88aceeabf1e48f59fdbb2b395675d117/layer.tar"
    ]
  },
  {
    "Config": "083d97e600105c9ada5a70068b19150edc0f08ecdfa5bdfa4bf90b80264174ae.json",
    "RepoTags": [
      "ko.local/test-0e3a563dcfe31cd0109fe43c1bf7c91e:66b8d4278a1d35faf75fcb39e2dc780287d93ce41e1354a87be9fd0947421f89"
    ],
    "Layers": [
      "774fa74f98be5577ec663365eef7c24c731c18bde0f1d4a44be8ca50372b076c/layer.tar",
      "a54428111bf69ae5f41b6c2ecd306edc87df992b44486e4ab9a0249cff680e13/layer.tar",
      "f4e1da5ab6010d8627624de1f1ccc455d56e415ae596fc03132d7234e85757fe/layer.tar"
    ]
  }
]

ko publish writes the images it produced to stdout, which is helpful for stuff like this.

[bioball]

That's a nice workaround! Although, I suspect this doesn't work for most use-cases, where the Docker daemon isn't available. This happens to be my use-case as well.

[jonjohnsonjr]

where the Docker daemon isn't available

Yeah this is one of the main benefits of ko, so we should definitely pursue #95 and add tarball support as well.