Improve WordPress's observability and increase health check timeout

src/charm.py

@@ -23,7 +23,6 @@
 import yaml
 from charms.data_platform_libs.v0.data_interfaces import DatabaseRequires
 from charms.grafana_k8s.v0.grafana_dashboard import GrafanaDashboardProvider
-from charms.loki_k8s.v0.loki_push_api import LogProxyConsumer
 from charms.nginx_ingress_integrator.v0.nginx_route import require_nginx_route
 from charms.prometheus_k8s.v0.prometheus_scrape import MetricsEndpointProvider
 from ops.charm import ActionEvent, CharmBase, HookEvent, PebbleReadyEvent, UpgradeCharmEvent
@@ -39,7 +38,7 @@
     _APACHE_EXPORTER_PEBBLE_SERVICE,
     APACHE_LOG_PATHS,
     PROM_EXPORTER_PEBBLE_CONFIG,
-    WORDPRESS_SCRAPE_JOBS,
+    ApacheLogProxyConsumer,
 )
 from state import CharmConfigInvalidError, State
 
@@ -150,12 +149,30 @@ def __init__(self, *args, **kwargs):
         )
 
         self._require_nginx_route()
+        self._logging = ApacheLogProxyConsumer(
+            self, relation_name="logging", log_files=APACHE_LOG_PATHS, container_name="wordpress"
+        )
+        prometheus_jobs = [
+            {
+                "job_name": "apache_exporter",
+                "static_configs": [{"targets": ["*:9117"]}],
+            }
+        ]
+        if self._logging.loki_endpoints:
+            prometheus_jobs.append(
+                {
+                    "job_name": "promtail",
+                    "static_configs": [{"targets": ["*:9080"]}],
+                }
+            )
         self.metrics_endpoint = MetricsEndpointProvider(
             self,
-            jobs=WORDPRESS_SCRAPE_JOBS,
-        )
-        self._logging = LogProxyConsumer(
-            self, relation_name="logging", log_files=APACHE_LOG_PATHS, container_name="wordpress"
+            jobs=prometheus_jobs,
+            refresh_event=[
+                self.on.wordpress_pebble_ready,
+                self._logging.on.log_proxy_endpoint_departed,
+                self._logging.on.log_proxy_endpoint_joined,
+            ],
         )
         self._grafana_dashboards = GrafanaDashboardProvider(self)
 
@@ -706,7 +723,8 @@ def _init_pebble_layer(self):
                 "wordpress-ready": {
                     "override": "replace",
                     "level": "alive",
-                    "http": {"url": "http://localhost/index.php"},
+                    "http": {"url": "http://localhost"},
+                    "timeout": "5s",
                 },
             },
         }

src/cos.py

@@ -6,6 +6,7 @@
 """COS integration for WordPress charm."""
 from typing import Dict, List, TypedDict
 
+from charms.loki_k8s.v0.loki_push_api import LogProxyConsumer
 from ops.pebble import Check, Layer, Service
 
 
@@ -40,17 +41,6 @@ class PrometheusMetricsJob(TypedDict, total=False):
 
 
 APACHE_PROMETHEUS_SCRAPE_PORT = "9117"
-WORDPRESS_SCRAPE_JOBS = [
-    PrometheusMetricsJob(
-        static_configs=[
-            PrometheusStaticConfig(
-                targets=[
-                    f"*:{APACHE_PROMETHEUS_SCRAPE_PORT}",
-                ]
-            )
-        ]
-    )
-]
 _APACHE_EXPORTER_PEBBLE_SERVICE = Service(
     name="apache-exporter",
     raw={
@@ -80,6 +70,73 @@ class PrometheusMetricsJob(TypedDict, total=False):
 )
 
 APACHE_LOG_PATHS = [
-    "/var/log/apache2/access.log",
-    "/var/log/apache2/error.log",
+    "/var/log/apache2/access.*.log",
+    "/var/log/apache2/error.*.log",
+]
+
+REQUEST_DURATION_MICROSECONDS_BUCKETS = [
+    10000,
+    25000,
+    50000,
+    100000,
+    200000,
+    300000,
+    400000,
+    500000,
+    750000,
+    1000000,
+    1500000,
+    2000000,
+    2500000,
+    5000000,
+    10000000,
 ]
+
+
+class ApacheLogProxyConsumer(LogProxyConsumer):
+    """Extends LogProxyConsumer to add a metrics pipeline to promtail."""
+
+    def _scrape_configs(self) -> dict:
+        """Generate the scrape_configs section of the Promtail config file.
+
+        Returns:
+            A dict representing the `scrape_configs` section.
+        """
+        scrape_configs = super()._scrape_configs()
+        scrape_configs["scrape_configs"].append(
+            {
+                "job_name": "access_log_exporter",
+                "static_configs": [{"labels": {"__path__": "/var/log/apache2/access.*.log"}}],
+                "pipeline_stages": [
+                    {
+                        "logfmt": {
+                            "mapping": {
+                                "request_duration_microseconds": "request_duration_microseconds",
+                                "content_type": "content_type",
+                                "path": "path",
+                            }
+                        }
+                    },
+                    {"labels": {"content_type": "content_type", "path": "path"}},
+                    {
+                        "match": {
+                            "selector": '{path=~"^/server-status.*$"}',
+                            "action": "drop",
+                        }
+                    },
+                    {"labeldrop": ["filename", "path"]},
+                    {
+                        "metrics": {
+                            "request_duration_microseconds": {
+                                "type": "Histogram",
+                                "source": "request_duration_microseconds",
+                                "prefix": "apache_access_log_",
+                                "config": {"buckets": REQUEST_DURATION_MICROSECONDS_BUCKETS},
+                            }
+                        }
+                    },
+                    {"drop": {"expression": ".*"}},
+                ],
+            }
+        )
+        return scrape_configs