Add crane mutate to set labels and entrypoint

[imjasonh]

Fixes #281

$ crane config $(go run ./cmd/crane mutate gcr.io/kontaindotme/mutated --entrypoint "blah blah blah" --label foo=bar) | jq .config
...
{
  "Entrypoint": [
    "blah",
    "blah",
    "blah"
  ],
  "Env": [
    "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
  ],
  "Labels": {
    "bar": "baz",
    "foo": "bar"
  }
}

(bar=baz was previously set during testing)

[imjasonh]

This now also allows setting the config platform, which is necessary if you're mutating an image based on scratch.

The use case for that is being able to append a file to a scratch image, then mutate it to set the entrypoint to that newly added file.

edit: This was silly. Just base it on a real image.

This change also updates crane append to output the pushed image by digest so it can be chained with crane mutate.

[imjasonh]

I can now append a file to an image, make it the entrypoint and run it in a one-liner:

$ docker run --rm $(
  go run ./cmd/crane mutate $(
    go run ./cmd/crane/ append -b busybox -f <(tar -f - -c hello.sh) -t gcr.io/kontaindotme/appended \
  ) --entrypoint=/hello.sh --new_ref=gcr.io/kontaindotme/mutated \
)
2021/04/16 10:44:33 No matching credentials were found for "index.docker.io/library/busybox", falling back on anonymous
2021/04/16 10:44:35 existing blob: sha256:f531cdc67389c92deac44e019e7a1b6fba90d1aaa58ae3e8192f0e0eed747152
2021/04/16 10:44:37 pushed blob: sha256:078105f9432ce9585d7f6b76a2bd0aed14b1bae9dec29ed679a6b5576cb89664
2021/04/16 10:44:37 existing blob: sha256:d6a3237b5852e9da63a291612928da68d814897550b15e9e0ca77934a8672792
2021/04/16 10:44:38 gcr.io/kontaindotme/appended: digest: sha256:a58979bf3493cbc9acea0541190c5621853bc57b4683970d847ba23ab3b660e4 size: 586
2021/04/16 10:44:42 existing blob: sha256:f531cdc67389c92deac44e019e7a1b6fba90d1aaa58ae3e8192f0e0eed747152
2021/04/16 10:44:42 existing blob: sha256:078105f9432ce9585d7f6b76a2bd0aed14b1bae9dec29ed679a6b5576cb89664
2021/04/16 10:44:43 existing blob: sha256:ed9106856a3626c48113f96ce859ff559829ae5c36088dac7ace491446963880
2021/04/16 10:44:43 gcr.io/kontaindotme/mutated: digest: sha256:7ce925f8db677b622bc66687662a5c07d0f4301ed2b221120102731701608f23 size: 586
Unable to find image 'gcr.io/kontaindotme/mutated@sha256:7ce925f8db677b622bc66687662a5c07d0f4301ed2b221120102731701608f23' locally
gcr.io/kontaindotme/mutated@sha256:7ce925f8db677b622bc66687662a5c07d0f4301ed2b221120102731701608f23: Pulling from kontaindotme/mutated
f531cdc67389: Already exists 
078105f9432c: Already exists 
Digest: sha256:7ce925f8db677b622bc66687662a5c07d0f4301ed2b221120102731701608f23
Status: Downloaded newer image for gcr.io/kontaindotme/mutated@sha256:7ce925f8db677b622bc66687662a5c07d0f4301ed2b221120102731701608f23
hello

[imjasonh]

Or, for Go binaries:

$ GOOS=linux GOARCH=amd64 go build ./cmd/crane
$ docker run --rm $(
  go run ./cmd/crane mutate $(
    go run ./cmd/crane/ append -b gcr.io/distroless/static:nonroot -f <(tar -f - -c crane) -t gcr.io/kontaindotme/appended \                       
  ) --entrypoint=/crane --new_ref=gcr.io/kontaindotme/mutated \                       
) --help
2021/04/16 10:51:30 existing blob: sha256:5dea5ec2316d4a067b946b15c3c4f140b4f2ad607e73e9bc41b673ee5ebb99a3
2021/04/16 10:51:32 pushed blob: sha256:4ea17cbd630f78759abeae1884169b19e68643838177ddeef8125ce1dee1cb31
2021/04/16 10:51:32 existing blob: sha256:c81e9ea13da6d0e1404f4b811ebdb1068b9590b701971ba070a40eba6166492f
2021/04/16 10:51:33 gcr.io/kontaindotme/appended: digest: sha256:7661392918a5df61dcbd64280d6ba5a650f0bda0fe8c46f72ffd131a31914f2c size: 590
2021/04/16 10:51:36 existing blob: sha256:4ea17cbd630f78759abeae1884169b19e68643838177ddeef8125ce1dee1cb31
2021/04/16 10:51:36 existing blob: sha256:5dea5ec2316d4a067b946b15c3c4f140b4f2ad607e73e9bc41b673ee5ebb99a3
2021/04/16 10:51:37 existing blob: sha256:9cb6f0d0bb92a09318ebee61068a91267e94c6156f09c9ff9b81fa84c3e9fdb0
2021/04/16 10:51:37 gcr.io/kontaindotme/mutated: digest: sha256:a55a9c00e09adeb3a025aa76651b5546bb588e408a3e4da6e3276193eaa77fb4 size: 590
Crane is a tool for managing container images

Usage:
  crane [flags]
...

[jonjohnsonjr]

This is glorious.

[codecov-commenter]

Codecov Report

Merging #982 (89253f0) into main (7b64627) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

❗ Current head 89253f0 differs from pull request most recent head 95a849b. Consider uploading reports for the commit 95a849b to get more accurate results

@@            Coverage Diff             @@
##             main     #982      +/-   ##
==========================================
- Coverage   74.60%   74.54%   -0.06%     
==========================================
  Files         107      107              
  Lines        5040     5040              
==========================================
- Hits         3760     3757       -3     
- Misses        725      727       +2     
- Partials      555      556       +1     

Impacted Files	Coverage Δ
pkg/crane/pull.go	69.56% <100.00%> (ø)
pkg/crane/push.go	100.00% <100.00%> (ø)
pkg/v1/daemon/write.go	34.61% <0.00%> (-11.54%)	⬇️

---

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