validate and test metric name

Author: saichandrapandraju

src/service/prometheus/prometheus_publisher.py

@@ -1,5 +1,6 @@
 import hashlib
 import logging
+import re
 import threading
 import uuid
 from typing import Dict, Optional
@@ -10,6 +11,11 @@
 
 logger: logging.Logger = logging.getLogger(__name__)
 
+# Prometheus metric name validation regex
+# Must start with letter, underscore, or colon
+# Can contain letters, numbers, underscores, and colons
+# Lowercase only (shall we allow uppercase?)
+PROMETHEUS_METRIC_NAME_REGEX = re.compile(r'^[a-z_:][a-z0-9_:]*$')
 
 class PrometheusPublisher:
     def __init__(self, registry: CollectorRegistry = REGISTRY) -> None:
@@ -164,7 +170,22 @@ def gauge(
             )
 
     def _get_full_metric_name(self, metric_name: str) -> str:
-        return f"{PROMETHEUS_METRIC_PREFIX}{metric_name.lower()}"
+        if not PROMETHEUS_METRIC_PREFIX.strip():
+            raise ValueError("Prometheus metric prefix cannot be empty")
+        if not metric_name.strip():
+            raise ValueError("Metric name cannot be empty")
+
+        full_name = f"{PROMETHEUS_METRIC_PREFIX}{metric_name.lower()}"
+        # Validate the full metric name against the regex
+        if not PROMETHEUS_METRIC_NAME_REGEX.match(full_name):
+            raise ValueError(
+                f"Invalid Prometheus metric name: '{metric_name}'. "
+                f"Metric names must start with a lowercase letter, "
+                f"underscore, or colon, and contain only lowercase letters, "
+                f"numbers, underscores, and colons."
+            )
+        
+        return full_name
 
     @staticmethod
     def generate_uuid(content: str) -> uuid.UUID:

tests/service/prometheus/test_prometheus_publisher.py

@@ -4,7 +4,6 @@
 
 import pytest
 
-# from unittest.mock import Mock, MagicMock, patch
 from prometheus_client import CollectorRegistry, Gauge
 from src.service.constants import PROMETHEUS_METRIC_PREFIX
 from src.service.payloads.metrics.base_metric_request import BaseMetricRequest
@@ -246,3 +245,57 @@ def test_invalid_gauge_parameters(
             match="Either 'request' or 'metric_name' & 'value' must be provided",
         ):
             publisher.gauge(model_name="test_model", id=test_id, value=0.5)
+    
+    def test_valid_metric_names(self, publisher: PrometheusPublisher):
+        """Test validation of valid Prometheus metric names."""
+        valid_names = [
+            "simple_metric",
+            "metric_with_numbers123",
+            "UPPERCASE_METRIC", # we convert to lowercase
+            "metric:with:colons",
+            "_underscore_start",
+            "a1b2c3",
+            "metric_name_with_3underscores"
+        ]
+        
+        for name in valid_names:
+            full_name = publisher._get_full_metric_name(name)
+            expected = f"{PROMETHEUS_METRIC_PREFIX}{name.lower()}"
+            assert full_name == expected
+
+    def test_invalid_metric_names(self, publisher: PrometheusPublisher):
+        """Test validation of invalid Prometheus metric names."""
+        invalid_names = [
+            "metric-with-hyphens",
+            "metric with spaces",
+            "metric@with@symbols",
+            "metric.with.dots",
+            "metric#with#hash",
+            "metric%with%percent",
+            "-starts_with_hyphen",
+            "metric/with/slashes"
+        ]
+        
+        for name in invalid_names:
+            with pytest.raises(ValueError, match="Invalid Prometheus metric name"):
+                publisher._get_full_metric_name(name)
+
+    def test_empty_metric_name_validation(self, publisher: PrometheusPublisher):
+        with pytest.raises(ValueError, match="Metric name cannot be empty"):
+            publisher._get_full_metric_name("")
+
+    def test_gauge_creation_with_invalid_metric_name(
+        self, publisher: PrometheusPublisher, mock_request: MockMetricRequest
+    ):
+        mock_request.metric_name = "invalid-metric-name"
+        
+        test_id = uuid.uuid4()
+        test_value = 0.5
+        
+        with pytest.raises(ValueError, match="Invalid Prometheus metric name"):
+            publisher.gauge(
+                model_name="test_model", 
+                id=test_id, 
+                value=test_value, 
+                request=mock_request
+            )