Add load(Map) overload to PrometheusPropertiesLoader

Signed-off-by: Jonatan Ivanov <[email protected]>

Author: jonatan-ivanov

prometheus-metrics-config/src/main/java/io/prometheus/metrics/config/PrometheusPropertiesLoader.java

@@ -25,7 +25,11 @@ public class PrometheusPropertiesLoader {
      * See {@link PrometheusProperties#get()}.
      */
     public static PrometheusProperties load() throws PrometheusPropertiesException {
-        Map<Object, Object> properties = loadProperties();
+        return load(new Properties());
+    }
+
+    public static PrometheusProperties load(Map<Object, Object> externalProperties) throws PrometheusPropertiesException {
+        Map<Object, Object> properties = loadProperties(externalProperties);
         Map<String, MetricsProperties> metricsConfigs = loadMetricsConfigs(properties);
         MetricsProperties defaultMetricsProperties = MetricsProperties.load("io.prometheus.metrics", properties);
         ExemplarsProperties exemplarConfig = ExemplarsProperties.load("io.prometheus.exemplars", properties);
@@ -72,11 +76,12 @@ private static void validateAllPropertiesProcessed(Map<Object, Object> propertie
         }
     }
 
-    private static Map<Object, Object> loadProperties() {
+    private static Map<Object, Object> loadProperties(Map<Object, Object> externalProperties) {
         Map<Object, Object> properties = new HashMap<>();
         properties.putAll(loadPropertiesFromClasspath());
         properties.putAll(loadPropertiesFromFile()); // overriding the entries from the classpath file
         properties.putAll(System.getProperties()); // overriding the entries from the properties file
+        properties.putAll(externalProperties); // overriding all the entries above
         // TODO: Add environment variables like EXEMPLARS_ENABLED.
         return properties;
     }

prometheus-metrics-config/src/test/java/io/prometheus/metrics/config/PrometheusPropertiesLoaderTests.java

@@ -0,0 +1,33 @@
+package io.prometheus.metrics.config;
+
+import java.util.Properties;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Tests for {@link PrometheusPropertiesLoader}.
+ */
+public class PrometheusPropertiesLoaderTests {
+
+	@Test
+	public void propertiesShouldBeLoadedFromPropertiesFile() {
+		PrometheusProperties prometheusProperties = PrometheusPropertiesLoader.load();
+		Assert.assertEquals(11, prometheusProperties.getDefaultMetricProperties().getHistogramClassicUpperBounds().size());
+		Assert.assertEquals(4, prometheusProperties.getMetricProperties("http_duration_seconds").getHistogramClassicUpperBounds().size());
+		Assert.assertTrue(prometheusProperties.getExporterProperties().getExemplarsOnAllMetricTypes());
+	}
+
+	@Test
+	public void externalPropertiesShouldOverridePropertiesFile() {
+		Properties properties = new Properties();
+		properties.setProperty("io.prometheus.metrics.histogramClassicUpperBounds", ".005, .01");
+		properties.setProperty("io.prometheus.metrics.http_duration_seconds.histogramClassicUpperBounds", ".005, .01, .015");
+		properties.setProperty("io.prometheus.exporter.exemplarsOnAllMetricTypes", "false");
+
+		PrometheusProperties prometheusProperties = PrometheusPropertiesLoader.load(properties);
+		Assert.assertEquals(2, prometheusProperties.getDefaultMetricProperties().getHistogramClassicUpperBounds().size());
+		Assert.assertEquals(3, prometheusProperties.getMetricProperties("http_duration_seconds").getHistogramClassicUpperBounds().size());
+		Assert.assertFalse(prometheusProperties.getExporterProperties().getExemplarsOnAllMetricTypes());
+	}
+}