Merge pull request #56 from kpetremann/crash_bad_char_metric_name

Crash bad char metric name

mqtt_exporter/main.py

@@ -9,7 +9,7 @@
 import sys
 
 import paho.mqtt.client as mqtt
-from prometheus_client import Counter, Gauge, start_http_server
+from prometheus_client import Counter, Gauge, metrics, start_http_server
 
 from mqtt_exporter import settings
 
@@ -61,6 +61,24 @@ def subscribe(client, _, __, result_code, *args):
         LOG.error("MQTT %s", mqtt.connack_string(result_code))
 
 
+def _normalize_prometheus_metric_name(prom_metric_name):
+    """Transform an invalid prometheus metric to a valid one.
+
+    https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
+    """
+    if metrics.METRIC_NAME_RE.match(prom_metric_name):
+        return prom_metric_name
+
+    # clean invalid characted
+    prom_metric_name = re.sub(r"[^a-zA-Z0-9_:]", "", prom_metric_name)
+
+    # ensure to start with valid character
+    if not re.match(r"^[a-zA-Z_:]", prom_metric_name):
+        prom_metric_name = ":" + prom_metric_name
+
+    return prom_metric_name
+
+
 def _create_prometheus_metric(prom_metric_name):
     """Create Prometheus metric if does not exist."""
     if not prom_metrics.get(prom_metric_name):
@@ -75,6 +93,9 @@ def _create_prometheus_metric(prom_metric_name):
 
 
 def _add_prometheus_sample(topic, prom_metric_name, metric_value, client_id):
+    if prom_metric_name not in prom_metrics:
+        return
+
     labels = {settings.TOPIC_LABEL: topic}
     if settings.MQTT_EXPOSE_CLIENT_ID:
         labels["client_id"] = client_id
@@ -142,7 +163,12 @@ def _parse_metrics(data, topic, client_id, prefix=""):
             .replace("/", "_")
         )
         prom_metric_name = re.sub(r"\((.*?)\)", "", prom_metric_name)
-        _create_prometheus_metric(prom_metric_name)
+        prom_metric_name = _normalize_prometheus_metric_name(prom_metric_name)
+        try:
+            _create_prometheus_metric(prom_metric_name)
+        except ValueError as error:
+            LOG.error("unable to create prometheus metric '%s': %s", prom_metric_name, error)
+            return
 
         # expose the sample to prometheus
         _add_prometheus_sample(topic, prom_metric_name, metric_value, client_id)

tests/functional/test_expose_metrics.py

@@ -20,10 +20,10 @@ def _exec(client_id, mocker):
     userdata = {"client_id": client_id}
     msg = mocker.Mock()
     msg.topic = "zigbee2mqtt/garage"
-    msg.payload = '{"temperature": "23.5", "humidity": "40.5"}'
+    msg.payload = '{"temperature°C": "23.5", "humidity": "40.5"}'
     main.expose_metrics(None, userdata, msg)
 
-    temperatures = main.prom_metrics["mqtt_temperature"].collect()
+    temperatures = main.prom_metrics["mqtt_temperatureC"].collect()
     humidity = main.prom_metrics["mqtt_humidity"].collect()
 
     return temperatures, humidity

tests/unit/__init__.py

@@ -0,0 +1 @@
+"""Unit tests."""

tests/unit/test_normalize_prometheus_name.py

@@ -0,0 +1,15 @@
+"""Tests of Prometheus normalization metrics."""
+from mqtt_exporter.main import _normalize_prometheus_metric_name
+
+
+def test_normalize_prometheus_metric_name():
+    """Test _normalize_prometheus_metric_name."""
+    tests = {
+        "1234invalid": ":1234invalid",
+        "valid1234": "valid1234",
+        "_this_is_valid": "_this_is_valid",
+        "not_so_valid%_name": "not_so_valid_name",
+    }
+
+    for candidate, wanted in tests.items():
+        assert _normalize_prometheus_metric_name(candidate) == wanted