chore(docs): mention rules_multirun (#681)

MODULE.bazel

@@ -7,9 +7,9 @@ module(
 )
 
 bazel_dep(name = "aspect_bazel_lib", version = "2.7.2")
+bazel_dep(name = "bazel_features", version = "1.10.0")
 bazel_dep(name = "bazel_skylib", version = "1.5.0")
 bazel_dep(name = "platforms", version = "0.0.8")
-bazel_dep(name = "bazel_features", version = "1.10.0")
 
 oci = use_extension("//oci:extensions.bzl", "oci")
 oci.toolchains()
@@ -34,3 +34,4 @@ use_repo(bazel_lib, "bsd_tar_toolchains", "jq_toolchains")
 bazel_dep(name = "rules_go", version = "0.46.0", dev_dependency = True, repo_name = "io_bazel_rules_go")
 bazel_dep(name = "gazelle", version = "0.35.0", dev_dependency = True, repo_name = "bazel_gazelle")
 bazel_dep(name = "bazel_skylib_gazelle_plugin", version = "1.4.1", dev_dependency = True)
+bazel_dep(name = "rules_multirun", version = "0.9.0", dev_dependency = True)

WORKSPACE

@@ -21,6 +21,11 @@ load("//oci:repositories.bzl", "oci_register_toolchains")
 
 oci_register_toolchains(name = "oci")
 
+# Transitive dep for rules_multirun
+load("@rules_python//python:repositories.bzl", "py_repositories")
+
+py_repositories()
+
 ## Setup bazel-lib
 load("@aspect_bazel_lib//lib:repositories.bzl", "aspect_bazel_lib_dependencies", "aspect_bazel_lib_register_toolchains")
 

examples/push/BUILD.bazel

@@ -1,4 +1,5 @@
 load("@aspect_bazel_lib//lib:expand_template.bzl", "expand_template")
+load("@rules_multirun//:defs.bzl", "command", "multirun")
 load("//oci:defs.bzl", "oci_image", "oci_image_index", "oci_push")
 
 oci_image(
@@ -47,11 +48,34 @@ expand_template(
     ],
 )
 
-oci_push(
-    name = "push_image_index",
-    image = ":image_index",
-    remote_tags = ":stamped",
-    repository = "index.docker.io/<ORG>/image",
+######
+# Demonstration of how to push to more than one repository
+REPOS = {
+    "index": "index.docker.io/<ORG>/image",
+    "ECR": "aws_account_id.dkr.ecr.us-west-2.amazonaws.com",
+}
+
+[
+    oci_push(
+        name = "push_image_" + k,
+        image = ":image_index",
+        remote_tags = ":stamped",
+        repository = v,
+    )
+    for (k, v) in REPOS.items()
+]
+
+[
+    command(
+        name = k,
+        command = "push_image_" + k,
+    )
+    for k in REPOS.keys()
+]
+
+multirun(
+    name = "push_all",
+    commands = REPOS.keys(),
 )
 
 sh_test(

internal_deps.bzl

@@ -58,3 +58,16 @@ def rules_oci_internal_deps():
             "https://github.com/bazelbuild/stardoc/releases/download/0.5.6/stardoc-0.5.6.tar.gz",
         ],
     )
+
+    http_archive(
+        name = "rules_multirun",
+        sha256 = "0e124567fa85287874eff33a791c3bbdcc5343329a56faa828ef624380d4607c",
+        url = "https://github.com/keith/rules_multirun/releases/download/0.9.0/rules_multirun.0.9.0.tar.gz",
+    )
+
+    http_archive(
+        name = "rules_python",
+        sha256 = "be04b635c7be4604be1ef20542e9870af3c49778ce841ee2d92fcb42f9d9516a",
+        strip_prefix = "rules_python-0.35.0",
+        url = "https://github.com/bazelbuild/rules_python/releases/download/0.35.0/rules_python-0.35.0.tar.gz",
+    )

oci/private/load.bzl

@@ -49,6 +49,37 @@ filegroup(
     output_group = "tarball",
 )
 ```
+
+### Multiple images
+
+To load more than one image into the daemon,
+use [rules_multirun] to group multiple oci_load targets into one executable target.
+
+This might be useful with a docker-compose workflow, for example.
+
+```starlark
+load("@rules_multirun//:defs.bzl", "command", "multirun")
+
+IMAGES = {
+    "webservice": "//path/to/web-service:image.load",
+    "backend": "//path/to/backend-service:image.load",
+}
+
+[
+    command(
+        name = k,
+        command = v,
+    )
+    for (k, v) in IMAGES.items()
+]
+
+multirun(
+    name = "load_all",
+    commands = IMAGES.keys(),
+)
+```
+
+[rules_multirun]: https://github.com/keith/rules_multirun
 """
 
 attrs = {

oci/private/push.bzl

@@ -96,6 +96,45 @@ oci_push(
     remote_tags = ":stamped",
 )
 ```
+
+To push to more than one registry, or using multiple remote tags,
+use [rules_multirun] to group multiple oci_push targets into one executable target.
+
+For example:
+
+```starlark
+load("@rules_multirun//:defs.bzl", "command", "multirun")
+
+REPOS = {
+    "index": "index.docker.io/<ORG>/image",
+    "ECR": "aws_account_id.dkr.ecr.us-west-2.amazonaws.com",
+}
+
+[
+    oci_push(
+        name = "push_image_" + k,
+        image = ":image_index",
+        remote_tags = ":stamped",
+        repository = v,
+    )
+    for (k, v) in REPOS.items()
+]
+
+[
+    command(
+        name = k,
+        command = "push_image_" + k,
+    )
+    for k in REPOS.keys()
+]
+
+multirun(
+    name = "push_all",
+    commands = REPOS.keys(),
+)
+```
+
+[rules_multirun]: https://github.com/keith/rules_multirun
 """
 
 # Helper rule for ensuring that the crane and yq toolchains are actually