Add prometheus metrics endpoint. Closes #67

core/prometheus_metrics_handler.py

@@ -0,0 +1,40 @@
+from bottle import response
+from prometheus_client import CollectorRegistry, generate_latest, CONTENT_TYPE_LATEST, Counter, disable_created_metrics, \
+    Gauge
+
+disable_created_metrics()
+# Prometheus metrics registry
+registry = CollectorRegistry()
+
+page_requests_counter = Counter(
+    "page_requests",
+    "Total number of page requests received",
+    registry=registry,
+)
+api_requests_counter = Counter(
+    "api_requests",
+    "Total number of API requests received",
+    registry=registry
+)
+spots_gauge = Gauge(
+    "spots",
+    "Number of spots currently in the software",
+    registry=registry
+)
+alerts_gauge = Gauge(
+    "alerts",
+    "Number of alerts currently in the software",
+    registry=registry
+)
+memory_use_gauge = Gauge(
+    "memory_usage_bytes",
+    "Current memory usage of the software in bytes",
+    registry=registry
+)
+
+
+# Get a Prometheus metrics response for Bottle
+def get_metrics():
+    response.content_type = CONTENT_TYPE_LATEST
+    response.status = 200
+    return generate_latest(registry)

core/status_reporter.py

@@ -7,6 +7,7 @@ import pytz
 
 from core.config import SERVER_OWNER_CALLSIGN
 from core.constants import SOFTWARE_VERSION
+from core.prometheus_metrics_handler import memory_use_gauge, spots_gauge, alerts_gauge
 
 
 # Provides a timed update of the application's status data.
@@ -60,8 +61,15 @@ class StatusReporter:
         self.status_data["webserver"] = {"status": self.web_server.status,
                                          "last_api_access": self.web_server.last_api_access_time.replace(
                                              tzinfo=pytz.UTC).timestamp() if self.web_server.last_api_access_time else 0,
+                                         "api_access_count": self.web_server.api_access_counter,
                                          "last_page_access": self.web_server.last_page_access_time.replace(
-                                             tzinfo=pytz.UTC).timestamp() if self.web_server.last_page_access_time else 0}
+                                             tzinfo=pytz.UTC).timestamp() if self.web_server.last_page_access_time else 0,
+                                         "page_access_count": self.web_server.page_access_counter}
+
+        # Update Prometheus metrics
+        memory_use_gauge.set(psutil.Process(os.getpid()).memory_info().rss * 1024)
+        spots_gauge.set(len(self.spots))
+        alerts_gauge.set(len(self.alerts))
 
         self.run_timer = Timer(self.run_interval, self.run)
         self.run_timer.start()

requirements.txt

@@ -11,3 +11,4 @@ psutil~=7.1.0
 requests-sse~=0.5.2
 rss-parser~=2.1.1
 pyproj~=3.7.2
+prometheus_client~=0.23.1

server/webserver.py

@@ -6,9 +6,11 @@ from threading import Thread
 import bottle
 import pytz
 from bottle import run, request, response, template
+from prometheus_client import CONTENT_TYPE_LATEST, generate_latest
 
 from core.config import MAX_SPOT_AGE, ALLOW_SPOTTING
 from core.constants import BANDS, ALL_MODES, MODE_TYPES, SIGS, CONTINENTS, SOFTWARE_VERSION
+from core.prometheus_metrics_handler import page_requests_counter, registry, get_metrics, api_requests_counter
 from data.spot import Spot
 
 
@@ -19,6 +21,8 @@ class WebServer:
     def __init__(self, spots, alerts, status_data, port):
         self.last_page_access_time = None
         self.last_api_access_time = None
+        self.page_access_counter = 0
+        self.api_access_counter = 0
         self.spots = spots
         self.alerts = alerts
         self.status_data = status_data
@@ -44,6 +48,8 @@ class WebServer:
         bottle.get("/status")(lambda: self.serve_template('webpage_status'))
         bottle.get("/about")(lambda: self.serve_template('webpage_about'))
         bottle.get("/apidocs")(lambda: self.serve_template('webpage_apidocs'))
+        # Route for Prometheus metrics
+        bottle.get("/metrics")(lambda: self.serve_prometheus_metrics())
         # Default route to serve from "webassets"
         bottle.get("/<filepath:path>")(self.serve_static_file)
 
@@ -92,6 +98,8 @@ class WebServer:
     # Serve a JSON API endpoint
     def serve_api(self, data):
         self.last_api_access_time = datetime.now(pytz.UTC)
+        self.api_access_counter += 1
+        api_requests_counter.inc()
         self.status = "OK"
         response.content_type = 'application/json'
         response.set_header('Cache-Control', 'no-store')
@@ -100,6 +108,8 @@ class WebServer:
     # Accept a spot
     def accept_spot(self):
         self.last_api_access_time = datetime.now(pytz.UTC)
+        self.api_access_counter += 1
+        api_requests_counter.inc()
         self.status = "OK"
 
         try:
@@ -153,6 +163,8 @@ class WebServer:
     # Serve a templated page
     def serve_template(self, template_name):
         self.last_page_access_time = datetime.now(pytz.UTC)
+        self.page_access_counter += 1
+        page_requests_counter.inc()
         self.status = "OK"
         return template(template_name)
 
@@ -160,6 +172,10 @@ class WebServer:
     def serve_static_file(self, filepath):
         return bottle.static_file(filepath, root="webassets")
 
+    # Serve Prometheus metrics
+    def serve_prometheus_metrics(self):
+        return get_metrics()
+
     # Utility method to apply filters to the overall spot list and return only a subset. Enables query parameters in
     # the main "spots" GET call.
     def get_spot_list_with_filters(self):