Add Prometheus exporter to ROCK (#67)

* adding exporter to rock

* address comments

content-cache_rock/rockcraft.yaml

@@ -15,6 +15,8 @@ parts:
       - nginx-light
       - bash
       - coreutils
+    stage-snaps:
+      - rocks-nginx-prometheus-exporter/latest/edge
   copy-config:
     plugin: dump
     source: .

metadata.yaml

@@ -35,18 +35,11 @@ source: https://github.com/canonical/content-cache-k8s-operator
 containers:
   content-cache:
     resource: content-cache-image
-  nginx-prometheus-exporter:
-    resource: nginx-prometheus-exporter-image
 
 resources:
   content-cache-image:
     type: oci-image
     description: Docker image for content-cache to run
-  nginx-prometheus-exporter-image:
-    type: oci-image
-    description: Prometheus exporter for nginx
-    auto-fetch: true
-    upstream-source: nginx/nginx-prometheus-exporter:0.11.0
 
 provides:
   metrics-endpoint:

src/charm.py

@@ -20,13 +20,7 @@
     IngressRequires,
 )
 from charms.prometheus_k8s.v0.prometheus_scrape import MetricsEndpointProvider
-from ops.charm import (
-    ActionEvent,
-    CharmBase,
-    ConfigChangedEvent,
-    PebbleReadyEvent,
-    UpgradeCharmEvent,
-)
+from ops.charm import ActionEvent, CharmBase, ConfigChangedEvent, UpgradeCharmEvent
 from ops.main import main
 from ops.model import ActiveStatus, BlockedStatus, MaintenanceStatus, WaitingStatus
 from tabulate import tabulate
@@ -79,10 +73,6 @@ def __init__(self, *args):
         self.framework.observe(
             self.on.content_cache_pebble_ready, self._on_content_cache_pebble_ready
         )
-        self.framework.observe(
-            self.on.nginx_prometheus_exporter_pebble_ready,
-            self._on_nginx_prometheus_exporter_pebble_ready,
-        )
         # Provide ability for Content-cache to be scraped by Prometheus using prometheus_scrape
         self._metrics_endpoint = MetricsEndpointProvider(
             self, jobs=[{"static_configs": [{"targets": ["*:9113"]}]}]
@@ -117,17 +107,6 @@ def _on_content_cache_pebble_ready(self, event) -> None:
         self.model.unit.status = MaintenanceStatus(msg)
         self.on.config_changed.emit()
 
-    def _on_nginx_prometheus_exporter_pebble_ready(self, event: PebbleReadyEvent) -> None:
-        """Handle content_cache_pebble_ready event and configure workload container.
-
-        Args:
-            event: Event triggering the pebble ready hook for the nginx prometheus exporter.
-        """
-        msg = "Configuring workload container (nginx-prometheus-exporter-pebble-ready)"
-        logger.info(msg)
-        self.model.unit.status = MaintenanceStatus(msg)
-        self.on.config_changed.emit()
-
     def _on_start(self, event) -> None:
         """Handle workload container started.
 
@@ -257,23 +236,10 @@ def configure_workload_container(self, event: ConfigChangedEvent) -> None:
                 logger.info(msg)
                 self.unit.status = MaintenanceStatus(msg)
                 container.add_layer(CONTAINER_NAME, pebble_config, combine=True)
+                container.add_layer(EXPORTER_CONTAINER_NAME, exporter_config, combine=True)
                 container.pebble.replan_services()
         else:
-            self.unit.status = WaitingStatus("Waiting for Pebble to start (content-cache)")
-            event.defer()
-            return
-
-        exporter_container = self.unit.get_container(EXPORTER_CONTAINER_NAME)
-        if exporter_container.can_connect():
-            msg = "Updating exporter pebble layer config"
-            logger.info(msg)
-            self.unit.status = MaintenanceStatus(msg)
-            exporter_container.add_layer(EXPORTER_CONTAINER_NAME, exporter_config, combine=True)
-            exporter_container.pebble.replan_services()
-        else:
-            self.unit.status = WaitingStatus(
-                "Waiting for Pebble to start (nginx-prometheus-exporter)"
-            )
+            self.unit.status = WaitingStatus("Waiting for Pebble to start")
             event.defer()
             return
 
@@ -298,13 +264,13 @@ def _get_nginx_prometheus_exporter_pebble_config(self):
         """Generate pebble config for the nginx-prometheus-exporter container.
 
         Returns:
-            Pebble layer config for the nginx-prometheus-exporter container.
+            Pebble layer config for the nginx-prometheus-exporter layer.
         """
         return {
             "summary": "Nginx prometheus exporter",
             "description": "Prometheus exporter for nginx",
             "services": {
-                "nginx-exporter": {
+                "nginx-prometheus-exporter": {
                     "override": "replace",
                     "summary": "Nginx Prometheus Exporter",
                     "command": (

tests/integration/conftest.py

@@ -93,12 +93,6 @@ async def get_unit_ip_list_action():
     yield get_unit_ip_list_action
 
 
-@fixture(scope="module")
-def nginx_prometheus_exporter_image(metadata):
-    """Provide the statsd prometheus exporter image from the metadata."""
-    yield metadata["resources"]["nginx-prometheus-exporter-image"]["upstream-source"]
-
-
 @pytest_asyncio.fixture(scope="function")
 async def unit_ip_list(get_unit_ip_list):
     """Yield ip addresses of current units."""
@@ -131,7 +125,6 @@ async def app(
     app_name: str,
     charm_file: str,
     content_cache_image: str,
-    nginx_prometheus_exporter_image: str,
     nginx_integrator_app: Application,
     run_action,
 ):
@@ -162,7 +155,6 @@ async def app(
         application_name=app_name,
         resources={
             "content-cache-image": content_cache_image,
-            "nginx-prometheus-exporter-image": nginx_prometheus_exporter_image,
         },
         series="jammy",
     )