chore: Create reusable workflow for codeowners linting

.github/workflows/codeowners.yml

@@ -0,0 +1,38 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+# Reusable workflow to lint CODEOWNERS files in our *-infra repos
+
+name: Lint CODEOWNERS
+
+on:
+  workflow_call:
+    inputs:
+      exclude_dirs:
+        description: 'Directories to exclude from linting (space-separated, e.g. "projects misc modules")'
+        type: string
+        required: false
+        default: ""
+
+jobs:
+  lint-codeowners:
+    runs-on: ubuntu-latest
+    container:
+      image: us-west1-docker.pkg.dev/moz-fx-platform-artifacts/platform-shared-images/sre-citools:1.0
+      options: --cpus 1
+    steps:
+      - name: Clone Repository
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - name: Lint CODEOWNERS
+        run: |
+          exclude_args=""
+          for dir in ${INPUTS_EXCLUDE_DIRS}; do
+            exclude_args="$exclude_args --excludedirs $dir"
+          done
+          /usr/bin/lint-codeowners $GITHUB_WORKSPACE $exclude_args
+        env:
+          INPUTS_EXCLUDE_DIRS: ${{ inputs.exclude_dirs }}

.github/workflows/docs/codeowners.md

@@ -0,0 +1,26 @@
+# CODEOWNERS Linting Reusable Workflow
+
+Validates CODEOWNERS files using the `lint-codeowners` tool found in [mozilla-it/sre-citools](https://github.com/mozilla-it/sre-citools).
+
+## Inputs
+
+| Name           | Required | Type   | Default | Description                                                              |
+| -------------- | -------- | ------ | ------- | ------------------------------------------------------------------------ |
+| `exclude_dirs` | false    | string | `""`    | Space-separated list of directories to exclude from linting (e.g. `"projects misc modules"`) |
+
+## Usage
+
+```yaml
+name: Lint CODEOWNERS
+
+on:
+  pull_request:
+    paths:
+      - 'CODEOWNERS'
+
+jobs:
+  lint-codeowners:
+    uses: mozilla-it/deploy-actions/.github/workflows/codeowners.yml@main
+    with:
+      exclude_dirs: "projects misc modules"  # optional: exclude specific directories
+```

README.md

@@ -8,6 +8,7 @@ This repository contains GitHub Actions Composite Actions used for Deployment Au
 
 ## Workflows
 * [build-and-push](./.github/workflows/docs/build-and-push.md)
+* [codeowners](./.github/workflows/docs/codeowners.md)
 * [diff-rendered-charts](./.github/workflows/docs/diff-rendered-charts.md)
 * [psa-checker](./.github/workflows/docs/psa-checker.md)
 * [validate-k8s-manifests](./.github/workflows/docs/validate-k8s-manifests.md)