Add COS integration and metric logs

.github/workflows/integration_test.yaml

@@ -10,7 +10,7 @@ jobs:
     with:
       juju-channel: 3.6/stable
       provider: lxd
-      modules: '["test_charm", "test_tls_cert"]'
+      modules: '["test_charm", "test_tls_cert", "test_metric"]'
       working-directory: ./content-cache
       self-hosted-runner: true
       self-hosted-runner-label: "edge"

.licenserc.yaml

@@ -20,4 +20,6 @@ header:
     - 'trivy.yaml'
     - 'pyproject.toml'
     - 'zap_rules.tsv'
+    # Ignore charm libraries.
+    - "**/lib/charms/**"
   comment: on-failure

content-cache/docs/changelog.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 2024-12-05
+
+### **Added**
+
+- Support for COS integration. Integrating with charms that provides cos-agent will cause the charm to forward logs to COS.
+
 ## 2024-11-28
 
 ### **Added**

content-cache/docs/how-to/enable-cos.md

@@ -0,0 +1,17 @@
+# How to enable COS integration
+
+The charm utilize nginx as a static web content cache.
+Various metrics on the requests to the cache are logged.
+The logs can be ingested into [COS](https://charmhub.io/topics/canonical-observability-stack) by integrating the charm with a charm that provides `cos-agent` integration.
+
+The [Grafana Agent charm](https://charmhub.io/grafana-agent) provides `cos-agent` integration to machine charms.
+If you are new to COS or the Grafana Agent charm it is recommended to first follow [this guide](https://charmhub.io/grafana-agent/docs/using) to understand the concepts of COS and how the charms work together.
+
+With a working content-cache charm deployment name `cache`, the following will add COS support to it:
+
+```bash
+juju deploy grafana-agent cos-agent
+juju integrate cos-agent cache
+```
+
+Then the Grafana Agent charm should be integrated with your COS instance.