Add ability to generate new artifact type

[jsturtevant]

The CNCF wg-wasm has published an OCI artifact format for packaging wasm modules and components. The artifact can be produced locally by running the --as-artifact flag:

cargo run --bin oci-tar-builder -- --name wasi-demo-oci --repo ghcr.io/containerd/runwasi --tag latest --as-artifact --module ./target/wasm32-wasi/debug/wasi-demo-app.wasm -o target/wasm32-wasi/debug/img-oci-artifact.tar
regctl image import localhost:5000/wasi-artifact:latest target/wasm32-wasi/debug/img-oci-artifact.tar

regctl manifest get localhost:5000/wasi-artifact:latest

Name:                                localhost:5000/wasi-artifact:latest
MediaType:                           application/vnd.oci.image.manifest.v1+json
Digest:                              sha256:7c31e635b3bef8b6c727a316e9a2dae777dbd184318d66a97da040fb11e37d70
Annotations:
  io.containerd.image.name:          ghcr.io/containerd/runwasi/wasi-demo-oci:latest
  org.opencontainers.image.ref.name: latest
Total Size:                          2.006MB

Config:
  Digest:                            sha256:24f30be41b447bbaf3644dad1e1c23dd28b597f36a5f455399657d65945816ea
  MediaType:                         application/vnd.wasm.config.v0+json
  Size:                              235B

Layers:

  Digest:                            sha256:0db51ed1c94837f422b2259c473758f298eef69605eaae6195bc043e25971e94
  MediaType:                         application/wasm
  Size:                              2.006MB

Note: this does not add support to runwasi to run these yet. Some work in Containerd is required: containerd/containerd#10179

[Mossaka]

Great work! Added some refactoring suggestions

[Mossaka]

suggestion:

Suggested change

	pub trait OciConfig {
	fn os(&self) -> String;
	fn architecture(&self) -> String;
	fn layers(&self) -> Vec<String>;
	fn to_string(&self) -> String;
	}
	pub trait OciConfig {
	fn os(&self) -> &str;
	fn architecture(&self) -> &str;
	fn layers(&self) -> &[String];
	}
	impl<T: OciConfig> ToString for T {
	fn to_string(&self) -> String {
	serde_json::to_string_pretty(self).unwrap()
	}
	}

[jsturtevant]

I tried this out but I get various errors like:

define and implement a trait or new type insteadrustc[Click for full compiler diagnostic](rust-analyzer-diagnostics-view:/diagnostic%20message%20%5B0%5D?0#file%3A%2F%2F%2Fhome%2Fjstur%2Fprojects%2Frunwasi%2Fcrates%2Foci-tar-builder%2Fsrc%2Flib.rs)
lib.rs(43, 19): `WasmConfig` is not defined in the current crate

| impl<T: OciConfig> ToString for T {
   |      ^ type parameter `T` must be used as the type parameter for some local type

I think this is again an issue with the fact that I am extending types outside of the current crate

[Mossaka]

nit: remove as the above suggestion derives Default trait

[jsturtevant]

I tried this suggestion but default marcro doesn't work since we have two different types, one of which doesn't have a default implementation

[jsturtevant]

I published an example to https://github.com/users/jsturtevant/packages/container/package/wasi-artifact

Can use the new tooling wkg to pull and run:

wkg oci pull ghcr.io/jsturtevant/wasi-artifact:latest
wasmtime run jsturtevant_wasi-artifact.wasm

This is a song that never ends.
Yes, it goes on and on my friends.

[jsturtevant]

I am not sure why the smoke test is failing, I've run the same tests locally and it doesn't timeout. I've also not modified any the shim or the test image.

[jsturtevant]

it is also only failing on ubuntu 20.04

[jsturtevant]

The musl build of wasmtime and the image built with these changes is working on ubuntu 20.04 for me locally

[jsturtevant]

/assign @devigned

[devigned]

lgtm! Great work, @jsturtevant!

Address concerns and Joe is away from keyboard right now