docs: add example for wasm containers (#81)

README.md

@@ -22,3 +22,5 @@ copy the WORKSPACE snippet into your `WORKSPACE` file.
 
 See the API documentation in the [docs](docs/) folder and the example usage in the [examples](examples/) folder.
 Note that the example relies on the setup code in the `/WORKSPACE` file in the root of this repo.
+
+Also, check out the [wasm containers](e2e/wasm/) end to end testing workspace for how to build wasm images.

docs/image.md

@@ -7,7 +7,8 @@ Implementation details for image rule
 ## oci_image
 
 <pre>
-oci_image(<a href="#oci_image-name">name</a>, <a href="#oci_image-architecture">architecture</a>, <a href="#oci_image-base">base</a>, <a href="#oci_image-cmd">cmd</a>, <a href="#oci_image-entrypoint">entrypoint</a>, <a href="#oci_image-env">env</a>, <a href="#oci_image-labels">labels</a>, <a href="#oci_image-os">os</a>, <a href="#oci_image-tars">tars</a>, <a href="#oci_image-user">user</a>, <a href="#oci_image-variant">variant</a>, <a href="#oci_image-workdir">workdir</a>)
+oci_image(<a href="#oci_image-name">name</a>, <a href="#oci_image-annotations">annotations</a>, <a href="#oci_image-architecture">architecture</a>, <a href="#oci_image-base">base</a>, <a href="#oci_image-cmd">cmd</a>, <a href="#oci_image-entrypoint">entrypoint</a>, <a href="#oci_image-env">env</a>, <a href="#oci_image-labels">labels</a>, <a href="#oci_image-os">os</a>, <a href="#oci_image-tars">tars</a>, <a href="#oci_image-user">user</a>,
+          <a href="#oci_image-variant">variant</a>, <a href="#oci_image-workdir">workdir</a>)
 </pre>
 
 Build an OCI compatible container image.
@@ -59,6 +60,7 @@ oci_image(
 | Name  | Description | Type | Mandatory | Default |
 | :------------- | :------------- | :------------- | :------------- | :------------- |
 | <a id="oci_image-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/docs/build-ref.html#name">Name</a> | required |  |
+| <a id="oci_image-annotations"></a>annotations |  Annotations for the image config. See https://github.com/opencontainers/image-spec/blob/main/annotations.md.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
 | <a id="oci_image-architecture"></a>architecture |  The CPU architecture which the binaries in this image are built to run on. eg: <code>arm64</code>, <code>arm</code>, <code>amd64</code>, <code>s390x</code>. See $GOARCH documentation for possible values: https://go.dev/doc/install/source#environment   | String | optional | "" |
 | <a id="oci_image-base"></a>base |  Label to an oci_image target to use as the base.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 | <a id="oci_image-cmd"></a>cmd |  Default arguments to the <code>entrypoint</code> of the container. These values act as defaults and may be replaced by any specified when creating a container.   | List of strings | optional | [] |

e2e/wasm/BUILD.bazel

@@ -0,0 +1,48 @@
+load("@rules_rust//rust:defs.bzl", "rust_binary")
+load("@aspect_bazel_lib//lib:transitions.bzl", "platform_transition_filegroup")
+load("@contrib_rules_oci//oci:defs.bzl", "oci_image", "oci_tarball")
+load("@rules_pkg//:pkg.bzl", "pkg_tar")
+
+package(default_visibility = ["//visibility:public"])
+
+rust_binary(
+    name = "binary",
+    srcs = ["main.rs"],
+    edition = "2018",
+)
+
+platform_transition_filegroup(
+    name = "wasi_binary",
+    srcs = ["binary"],
+    target_platform = "@rules_rust//rust/platform:wasi",
+)
+
+pkg_tar(
+    name = "wasi_layer",
+    srcs = ["wasi_binary"],
+)
+
+oci_image(
+    name = "image",
+    annotations = {
+        "module.wasm.image/variant": "compat",
+        "run.oci.handler": "wasm",
+    },
+    architecture = "wasm32",
+    cmd = ["/binary.wasm"],
+    os = "wasi",
+    tars = [
+        ":wasi_layer",
+    ],
+)
+
+# In order to run the image you need to follow instructions at https://docs.docker.com/desktop/wasm/ first.
+# then run the following;
+#  `bazel build :tarball`
+#  `docker load -i bazel-bin/tarball/tarball.tar`
+#  `docker run --runtime=io.containerd.wasmedge.v1 --platform=wasi/wasm32 --pull=never gcr.io/wasm:latest`
+oci_tarball(
+    name = "tarball",
+    image = ":image",
+    repotags = ["gcr.io/wasm:latest"],
+)

e2e/wasm/WORKSPACE

@@ -0,0 +1,48 @@
+workspace(name = "custom_registry_example")
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+local_repository(
+    name = "contrib_rules_oci",
+    path = "../../",
+)
+
+load("@contrib_rules_oci//oci:dependencies.bzl", "rules_oci_dependencies")
+
+# Fetch our "runtime" dependencies which users need as well
+rules_oci_dependencies()
+
+load("@contrib_rules_oci//oci:repositories.bzl", "LATEST_CRANE_VERSION", "LATEST_ZOT_VERSION", "oci_register_toolchains")
+
+oci_register_toolchains(
+    name = "oci",
+    crane_version = LATEST_CRANE_VERSION,
+    zot_version = LATEST_ZOT_VERSION,
+)
+
+# rules_pkg
+http_archive(
+    name = "rules_pkg",
+    sha256 = "451e08a4d78988c06fa3f9306ec813b836b1d076d0f055595444ba4ff22b867f",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.7.1/rules_pkg-0.7.1.tar.gz",
+        "https://github.com/bazelbuild/rules_pkg/releases/download/0.7.1/rules_pkg-0.7.1.tar.gz",
+    ],
+)
+
+load("@rules_pkg//:deps.bzl", "rules_pkg_dependencies")
+
+rules_pkg_dependencies()
+
+# rules_rust
+http_archive(
+    name = "rules_rust",
+    sha256 = "2466e5b2514772e84f9009010797b9cd4b51c1e6445bbd5b5e24848d90e6fb2e",
+    urls = ["https://github.com/bazelbuild/rules_rust/releases/download/0.18.0/rules_rust-v0.18.0.tar.gz"],
+)
+
+load("@rules_rust//rust:repositories.bzl", "rules_rust_dependencies", "rust_register_toolchains")
+
+rules_rust_dependencies()
+
+rust_register_toolchains(edition = "2022")

e2e/wasm/main.rs

@@ -0,0 +1,4 @@
+
+fn main() {
+    println!("Hello world!");
+}

oci/private/image.bzl

@@ -63,6 +63,7 @@ If `group/gid` is not specified, the default group and supplementary groups of t
     "architecture": attr.string(doc = "The CPU architecture which the binaries in this image are built to run on. eg: `arm64`, `arm`, `amd64`, `s390x`. See $GOARCH documentation for possible values: https://go.dev/doc/install/source#environment"),
     "variant": attr.string(doc = "The variant of the specified CPU architecture. eg: `v6`, `v7`, `v8`. See: https://github.com/opencontainers/image-spec/blob/main/image-index.md#platform-variants for more."),
     "labels": attr.string_dict(doc = "Labels for the image config. See https://github.com/opencontainers/image-spec/blob/main/annotations.md."),
+    "annotations": attr.string_dict(doc = "Annotations for the image config. See https://github.com/opencontainers/image-spec/blob/main/annotations.md."),
     "_image_sh_tpl": attr.label(default = "image.sh.tpl", allow_single_file = True),
 }
 
@@ -143,6 +144,9 @@ def _oci_image_impl(ctx):
         # TODO: Support stamping the values
         args.add_all(ctx.attr.labels.items(), map_each = _format_string_to_string_tuple, format_each = "--label=%s")
 
+    if ctx.attr.annotations:
+        args.add_all(ctx.attr.annotations.items(), map_each = _format_string_to_string_tuple, format_each = "--annotation=%s")
+
     output = ctx.actions.declare_directory(ctx.label.name)
     args.add(output.path, format = "--output=%s")