Post build config to generate an image

[imjasonh]

@jonjohnsonjr had an idea:

docker run $(curl -X POST --data-binary @image.yaml https://build.kontain.me)

Instead of trying to express the build config (what to build, how to build) in registry-API-compatible URL params, send the config in a POST to an API, which responds with the image URL where it will serve the built image when it's done, e.g., build.kontain.me/14213b68-9120-448e-a368-f267ec2524d5

That build config could be YAML, JSON, a tar file containing source, tons of stuff.

Good idea Jon.

[imjasonh]

Off the top of my head, the request could be, based on Shipwright's API:

source:
  url: https://github.com/foo/bar
strategy:
  name: buildpacks-v3
async: true

• If async:false, requests for build.kontain.me/<uuid> block until the image is built (or if it fails, serve an error)
• If async:true, requests fail immediately with an error until the image is built, assuming the client (e.g., K8s) will ImagePullBackOff until the image can successfully be served.

[jonjohnsonjr]

async: true

Could we rely on HTTP semantics instead, somehow?

[imjasonh]

Could we rely on HTTP semantics instead, somehow?

How do you mean?

[imjasonh]

This model could also be used to describe packages to include in the image using something like https://nixery.dev/,

packages:
- shell@v1
- git@v2
- htop@v3

...or to explicitly specify image content and augmentations on base images:

baseImage: gcr.io/distroless/static@sha256:deadbeef
files:
  /path/to/foo: i am foo
  /path/to/bar: i am bar

---

Instead of a UUID, the generated image name could be derived from the SHA of the input YAML description, e.g.:

build.kontain.me/<sha-of-the-yaml>

...so that pushing identical YAML immediately returns the previously built reference.

Users might also want some way to describe their own tags for the resulting image, e.g.:

curl -X POST build.kontain.me/custom/path:custom-tag

...but in general we can also just expect them to copy the resulting image to their own registry immediately after it's built:

crane cp $(curl -X POST https://build.kontain.me) gcr.io/my-project/my-image:my-tag