Introduce JAEGER_CONFIG_MANAGER_ENDPOINT property

Introduce a new property, JAEGER_CONFIG_MANAGER_ENDPOINT, that should be
set to the URL of the Jaeger Config Manager sampling endpoint. If not
set, fall back to the now-deprecated JAEGER_SAMPLER_MANAGER_HOST_PORT as
the host and port of the URL.

If JAEGER_AGENT_HOST has been set as a property, further fall back to
that value as the host of the URL (using the default port of 5778).

This brings the SamplerConfiguration in-line with the Go client.

See also:
 * jaegertracing#521
 * jaegertracing#547
 * jaegertracing/jaeger-client-go#326
 * jaegertracing/jaeger-client-go#282

Signed-off-by: Luke Wood <luke@lwood.me.uk>

jaeger-core/src/main/java/io/jaegertracing/Configuration.java

@@ -123,6 +123,11 @@ public class Configuration {
    */
   public static final String JAEGER_SAMPLER_MANAGER_HOST_PORT = JAEGER_PREFIX + "SAMPLER_MANAGER_HOST_PORT";
 
+  /**
+   * The config manager endpoint URL.
+   */
+  public static final String JAEGER_CONFIG_MANAGER_ENDPOINT = JAEGER_PREFIX + "CONFIG_MANAGER_ENDPOINT";
+
   /**
    * The service name.
    */
@@ -332,26 +337,36 @@ public static class SamplerConfiguration {
     private Number param;
 
     /**
-     * HTTP host:port of the sampling manager that can provide sampling strategy to this service.
+     * HTTP URL of the sampling manager that can provide sampling strategy to this service.
      * Optional.
      */
-    private String managerHostPort;
+    private String serverUrl;
 
     public SamplerConfiguration() {
     }
 
     public static SamplerConfiguration fromEnv() {
+      String configManagerEndpoint = getProperty(JAEGER_CONFIG_MANAGER_ENDPOINT);
+      if (configManagerEndpoint == null) {
+        if (getProperty(JAEGER_SAMPLER_MANAGER_HOST_PORT) != null) {
+          configManagerEndpoint = "http://" + getProperty(JAEGER_SAMPLER_MANAGER_HOST_PORT) + "/sampling";
+        } else if (getProperty(JAEGER_AGENT_HOST) != null) {
+          configManagerEndpoint = "http://" + getProperty(JAEGER_AGENT_HOST) + ":"
+                  + HttpSamplingManager.DEFAULT_SERVER_PORT + "/sampling";
+        }
+      }
+
       return new SamplerConfiguration()
           .withType(getProperty(JAEGER_SAMPLER_TYPE))
           .withParam(getPropertyAsNum(JAEGER_SAMPLER_PARAM))
-          .withManagerHostPort(getProperty(JAEGER_SAMPLER_MANAGER_HOST_PORT));
+          .withServerUrl(configManagerEndpoint);
     }
 
     // for tests
     Sampler createSampler(String serviceName, Metrics metrics) {
       String samplerType = stringOrDefault(this.getType(), RemoteControlledSampler.TYPE);
       Number samplerParam = numberOrDefault(this.getParam(), ProbabilisticSampler.DEFAULT_SAMPLING_PROBABILITY);
-      String hostPort = stringOrDefault(this.getManagerHostPort(), HttpSamplingManager.DEFAULT_HOST_PORT);
+      String serverUrl = stringOrDefault(this.getServerUrl(), HttpSamplingManager.DEFAULT_SERVER_URL);
 
       if (samplerType.equals(ConstSampler.TYPE)) {
         return new ConstSampler(samplerParam.intValue() != 0);
@@ -367,7 +382,7 @@ Sampler createSampler(String serviceName, Metrics metrics) {
 
       if (samplerType.equals(RemoteControlledSampler.TYPE)) {
         return new RemoteControlledSampler.Builder(serviceName)
-            .withSamplingManager(new HttpSamplingManager(hostPort))
+            .withSamplingManager(new HttpSamplingManager(serverUrl))
             .withInitialSampler(new ProbabilisticSampler(samplerParam.doubleValue()))
             .withMetrics(metrics)
             .build();
@@ -384,8 +399,8 @@ public Number getParam() {
       return param;
     }
 
-    public String getManagerHostPort() {
-      return managerHostPort;
+    public String getServerUrl() {
+      return serverUrl;
     }
 
     public SamplerConfiguration withType(String type) {
@@ -398,8 +413,17 @@ public SamplerConfiguration withParam(Number param) {
       return this;
     }
 
+    /**
+     * @deprecated Use {@link #withServerUrl(String)} instead
+     */
+    @Deprecated
     public SamplerConfiguration withManagerHostPort(String managerHostPort) {
-      this.managerHostPort = managerHostPort;
+      this.serverUrl = "http://" + managerHostPort + "/sampling";
+      return this;
+    }
+
+    public SamplerConfiguration withServerUrl(String serverUrl) {
+      this.serverUrl = serverUrl;
       return this;
     }
   }

jaeger-core/src/main/java/io/jaegertracing/internal/samplers/HttpSamplingManager.java

@@ -28,20 +28,23 @@
 
 @ToString
 public class HttpSamplingManager implements SamplingManager {
-  public static final String DEFAULT_HOST_PORT = "localhost:5778";
-  private final String hostPort;
+  public static final String DEFAULT_SERVER_HOST = "localhost";
+  public static final int DEFAULT_SERVER_PORT = 5778;
+  public static final String DEFAULT_SERVER_URL =
+          "http://" + DEFAULT_SERVER_HOST + ":" + DEFAULT_SERVER_PORT + "/sampling";
+  private final String serverUrl;
 
   @ToString.Exclude private final Gson gson = new Gson();
 
   /**
-   * This constructor expects running sampling manager on {@link #DEFAULT_HOST_PORT}.
+   * This constructor expects running sampling manager on {@link #DEFAULT_SERVER_URL}.
    */
   public HttpSamplingManager() {
-    this(DEFAULT_HOST_PORT);
+    this(DEFAULT_SERVER_URL);
   }
 
-  public HttpSamplingManager(String hostPort) {
-    this.hostPort = hostPort != null ? hostPort : DEFAULT_HOST_PORT;
+  public HttpSamplingManager(String serverUrl) {
+    this.serverUrl = serverUrl != null ? serverUrl : DEFAULT_SERVER_URL;
   }
 
   SamplingStrategyResponse parseJson(String json) {
@@ -59,7 +62,7 @@ public SamplingStrategyResponse getSamplingStrategy(String serviceName)
     try {
       jsonString =
           makeGetRequest(
-              "http://" + hostPort + "/?service=" + URLEncoder.encode(serviceName, "UTF-8"));
+              serverUrl + "?service=" + URLEncoder.encode(serviceName, "UTF-8"));
     } catch (IOException e) {
       throw new SamplingStrategyErrorException(
           "http call to get sampling strategy from local agent failed.", e);

jaeger-core/src/test/java/io/jaegertracing/ConfigurationTest.java

@@ -62,6 +62,7 @@ public void clearProperties() throws NoSuchFieldException, IllegalAccessExceptio
     System.clearProperty(Configuration.JAEGER_SAMPLER_TYPE);
     System.clearProperty(Configuration.JAEGER_SAMPLER_PARAM);
     System.clearProperty(Configuration.JAEGER_SAMPLER_MANAGER_HOST_PORT);
+    System.clearProperty(Configuration.JAEGER_CONFIG_MANAGER_ENDPOINT);
     System.clearProperty(Configuration.JAEGER_SERVICE_NAME);
     System.clearProperty(Configuration.JAEGER_TAGS);
     System.clearProperty(Configuration.JAEGER_ENDPOINT);
@@ -110,6 +111,36 @@ public void testSamplerConstInvalidParam() {
     assertNull(samplerConfig.getParam());
   }
 
+  @Test
+  public void testConfigManagerUrl() {
+    System.setProperty(Configuration.JAEGER_CONFIG_MANAGER_ENDPOINT, "http://example.com/sampling");
+    SamplerConfiguration samplerConfig = SamplerConfiguration.fromEnv();
+    assertEquals("http://example.com/sampling", samplerConfig.getServerUrl());
+  }
+
+  @Test
+  public void testConfigManagerUrlOverridesSamplerManagerHostPort() {
+    System.setProperty(Configuration.JAEGER_CONFIG_MANAGER_ENDPOINT, "http://example.com/sampling");
+    System.setProperty(Configuration.JAEGER_SAMPLER_MANAGER_HOST_PORT, "example.org:80");
+    SamplerConfiguration samplerConfig = SamplerConfiguration.fromEnv();
+    assertEquals("http://example.com/sampling", samplerConfig.getServerUrl());
+  }
+
+  @Test
+  public void testSamplerManagerHostPortOverridesAgentHost() {
+    System.setProperty(Configuration.JAEGER_SAMPLER_MANAGER_HOST_PORT, "example.org:80");
+    System.setProperty(Configuration.JAEGER_AGENT_HOST, "example.com");
+    SamplerConfiguration samplerConfig = SamplerConfiguration.fromEnv();
+    assertEquals("http://example.org:80/sampling", samplerConfig.getServerUrl());
+  }
+
+  @Test
+  public void testAgentHostOverridesDefault() {
+    System.setProperty(Configuration.JAEGER_AGENT_HOST, "example.com");
+    SamplerConfiguration samplerConfig = SamplerConfiguration.fromEnv();
+    assertEquals("http://example.com:5778/sampling", samplerConfig.getServerUrl());
+  }
+
   @Test
   public void testReporterConfiguration() {
     System.setProperty(Configuration.JAEGER_REPORTER_LOG_SPANS, "true");

jaeger-core/src/test/java/io/jaegertracing/internal/samplers/HttpSamplingManagerTest.java

@@ -67,7 +67,7 @@ protected Application configure() {
   @Test
   public void testGetSamplingStrategy() throws Exception {
     URI uri = target().getUri();
-    undertest = new HttpSamplingManager(uri.getHost() + ":" + uri.getPort());
+    undertest = new HttpSamplingManager("http://" + uri.getHost() + ":" + uri.getPort());
     SamplingStrategyResponse response = undertest.getSamplingStrategy("clairvoyant");
     assertNotNull(response.getProbabilisticSampling());
   }