Sanitize label names to comply with Prometheus requirements (#1253)

* Sanitize label names to comply with Prometheus requirements Signed-off-by: Tom Kerkhove <[email protected]> * Add new metric Signed-off-by: Tom Kerkhove <[email protected]> * Description Signed-off-by: Tom Kerkhove <[email protected]>
tomkerkhove · Aug 31, 2020 · d423406 · d423406
1 parent 014c89a
commit d423406
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Showing 4 changed files with 90 additions and 5 deletions.
diff --git a/config/promitor/scraper/metrics.yaml b/config/promitor/scraper/metrics.yaml
@@ -127,4 +127,16 @@ metrics:
       aggregation:
         type: Total
     resourceDiscoveryGroups:
-    - name: service-bus-landscape
+    - name: service-bus-landscape
+  - name: promitor_demo_app_insights
+    description: "Average dependency duration per dependency type"
+    resourceType: Generic
+    azureMetricConfiguration:
+      metricName: dependencies/duration
+      dimension:
+        name: dependency/type
+      aggregation:
+        type: Average
+    resources:
+    - resourceUri: Microsoft.Insights/Components/docker-hub-metrics
+      resourceGroupName: docker-hub-metrics
diff --git a/src/Promitor.Integrations.Sinks.Prometheus/Extensions/StringExtensions.cs b/src/Promitor.Integrations.Sinks.Prometheus/Extensions/StringExtensions.cs
@@ -0,0 +1,21 @@
+// ReSharper disable once CheckNamespace
+
+namespace System
+{
+    public static class StringExtensions
+    {
+        /// <summary>
+        ///     Ensures label key name is valid according to Prometheus requirements
+        /// </summary>
+        /// <param name="labelKey">Current label key value</param>
+        public static string SanitizeForPrometheusLabelKey(this string labelKey)
+        {
+            if (string.IsNullOrWhiteSpace(labelKey))
+            {
+                return labelKey;
+            }
+
+            return labelKey.Replace("/", "_").ToLower();
+        }
+    }
+}
diff --git a/src/Promitor.Integrations.Sinks.Prometheus/PrometheusScrapingEndpointMetricSink.cs b/src/Promitor.Integrations.Sinks.Prometheus/PrometheusScrapingEndpointMetricSink.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using GuardNet;
@@ -85,18 +86,18 @@ private IMetricFamily<IGauge> CreateGauge(string metricName, string metricDescri
 
         private Dictionary<string, string> DetermineLabels(PrometheusMetricDefinition metricDefinition, ScrapeResult scrapeResult, MeasuredMetric measuredMetric)
         {
-            var labels = new Dictionary<string, string>(scrapeResult.Labels.Select(label => new KeyValuePair<string, string>(label.Key.ToLower(), label.Value)));
+            var labels = new Dictionary<string, string>(scrapeResult.Labels.Select(label => new KeyValuePair<string, string>(label.Key.SanitizeForPrometheusLabelKey(), label.Value)));
 
             if (measuredMetric.IsDimensional)
             {
-                labels.Add(measuredMetric.DimensionName.ToLower(), measuredMetric.DimensionValue);
+                labels.Add(measuredMetric.DimensionName.SanitizeForPrometheusLabelKey(), measuredMetric.DimensionValue);
             }
 
             if (metricDefinition?.Labels?.Any() == true)
             {
                 foreach (var customLabel in metricDefinition.Labels)
                 {
-                    var customLabelKey = customLabel.Key.ToLower();
+                    var customLabelKey = customLabel.Key.SanitizeForPrometheusLabelKey();
                     if (labels.ContainsKey(customLabelKey))
                     {
                         _logger.LogWarning("Custom label {CustomLabelName} was already specified with value 'LabelValue' instead of 'CustomLabelValue'. Ignoring...", customLabel.Key, labels[customLabelKey], customLabel.Value);

diff --git a/src/Promitor.Tests.Unit/Prometheus/StringExtensionTests.cs b/src/Promitor.Tests.Unit/Prometheus/StringExtensionTests.cs
@@ -0,0 +1,51 @@
+using System;
+using System.ComponentModel;
+using Xunit;
+
+namespace Promitor.Tests.Unit.Prometheus
+{
+    [Category("Unit")]
+    public class StringExtensionTests
+    {
+        [Fact]
+        public void SanitizeForPrometheusLabelKey_ValidKey_IdenticalOutput()
+        {
+            // Arrange
+            var labelKeyInput = "sample_label";
+
+            // Act
+            var sanitizedLabelKey = labelKeyInput.SanitizeForPrometheusLabelKey();
+
+            // Assert
+            Assert.Equal(labelKeyInput, sanitizedLabelKey);
+        }
+
+        [Fact]
+        public void SanitizeForPrometheusLabelKey_KeyIsUppercase_ConvertedToLowercase()
+        {
+            // Arrange
+            var labelKeyInput = "SAMPLE_LABEL";
+            var expectedLabelKey = "sample_label";
+
+            // Act
+            var sanitizedLabelKey = labelKeyInput.SanitizeForPrometheusLabelKey();
+
+            // Assert
+            Assert.Equal(expectedLabelKey, sanitizedLabelKey);
+        }
+
+        [Fact]
+        public void SanitizeForPrometheusLabelKey_KeyWithSlash_SlashIsReplaced()
+        {
+            // Arrange
+            var labelKeyInput = "sample/label";
+            var expectedLabelKey = "sample_label";
+
+            // Act
+            var sanitizedLabelKey = labelKeyInput.SanitizeForPrometheusLabelKey();
+
+            // Assert
+            Assert.Equal(expectedLabelKey, sanitizedLabelKey);
+        }
+    }
+}