feat: enable log forwarding through otel collector

.github/workflows/enable_log_forwarding_action_tests.yaml

@@ -0,0 +1,90 @@
+name: Enable Log Forwarding Action Tests
+
+on:
+  pull_request:
+  workflow_call:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  detect-changes:
+    runs-on: ubuntu-latest
+    outputs:
+      action: ${{ steps.filter.outputs.action }}
+    steps:
+      - uses: actions/checkout@v6
+      - uses: dorny/paths-filter@v4
+        id: filter
+        with:
+          filters: |
+            action:
+              - 'actions/enable-log-forwarding/**'
+              - '.github/workflows/enable_log_forwarding_action_tests.yaml'
+
+  test-action:
+    needs: detect-changes
+    if: ${{ needs.detect-changes.outputs.action == 'true' }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+
+      - name: Set up uv
+        uses: astral-sh/setup-uv@v8.1.0
+
+      - name: Install tox
+        run: uv tool install tox --with tox-uv
+
+      - name: Run lint, static checks, and unit tests
+        run: tox -e actions-lint,actions-static,actions-unit
+
+  smoke-test-self-hosted:
+    needs: detect-changes
+    if: ${{ needs.detect-changes.outputs.action == 'true' }}
+    runs-on: [self-hosted-linux-amd64-noble-edge]
+    env:
+      TEST_CONFIG_FILE: 91-enable-log-forwarding-smoke-${{ github.run_id }}-${{ github.run_attempt }}.yaml
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Run enable log forwarding action
+        uses: ./actions/enable-log-forwarding
+        with:
+          files: |
+            /var/log/syslog
+          config-file-name: ${{ env.TEST_CONFIG_FILE }}
+          otlp-endpoint: 127.0.0.1:4317
+
+      - name: Verify generated config file exists
+        run: |
+          sudo test -f /etc/otelcol/config.d/${TEST_CONFIG_FILE}
+
+      - name: Verify generated config contains expected receiver
+        run: |
+          sudo grep -q '"filelog/github_runner_optin"' /etc/otelcol/config.d/${TEST_CONFIG_FILE}
+
+  smoke-test-github-hosted:
+    needs: detect-changes
+    if: ${{ needs.detect-changes.outputs.action == 'true' }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Run enable log forwarding action on github-hosted runner
+        uses: ./actions/enable-log-forwarding
+        with:
+          files: |
+            /var/log/syslog
+
+      - name: Verify workflow continues after github-hosted no-op
+        run: |
+          echo "enable-log-forwarding exited successfully on github-hosted runner"

actions/enable-log-forwarding/action.yaml

@@ -0,0 +1,39 @@
+# Copyright 2026 Canonical Ltd.
+# See LICENSE file for licensing details.
+name: Enable log forwarding
+description: Opt in to forward selected log files from a self-hosted GitHub runner to Loki.
+
+inputs:
+  files:
+    description: |
+      Newline or comma-separated list of file paths and glob patterns to forward.
+      Examples:
+        newline-separated: /var/log/syslog\n/var/log/kern.log
+        comma-separated: /var/log/syslog,/var/log/kern.log
+        glob: /var/log/chrony/*.log
+    required: true
+  otlp-endpoint:
+    description: |
+      Optional OTLP/gRPC endpoint for upstream OpenTelemetry Collector logs export.
+      When not set, the action falls back to ACTION_OTEL_EXPORTER_OTLP_ENDPOINT,
+      which is injected by Canonical self-hosted runners.
+      Example: otel-gateway.internal:4317
+    required: false
+    default: ""
+  config-file-name:
+    description: |
+      File name for the generated collector fragment under /etc/otelcol/config.d.
+      Use this to control merge/load priority relative to other fragments.
+    required: false
+    default: 90-github-runner-log-forwarding.yaml
+
+runs:
+  using: composite
+  steps:
+    - name: Configure collector for opt-in file log forwarding
+      shell: bash
+      env:
+        INPUT_FILES: ${{ inputs.files }}
+        INPUT_OTLP_ENDPOINT: ${{ inputs.otlp-endpoint }}
+        INPUT_CONFIG_FILE_NAME: ${{ inputs.config-file-name }}
+      run: python3 "${{ github.action_path }}/enable_log_forwarding.py"