Allowing docker container host to be set as hostname in riemann metric datapoints

src/main/java/com/codahale/metrics/riemann/DropWizardRiemannReporter.java

@@ -24,8 +24,6 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
-import java.net.InetAddress;
-import java.net.UnknownHostException;
 import java.util.*;
 import java.util.concurrent.TimeUnit;
 
@@ -69,14 +67,10 @@ private Builder(MetricRegistry registry) {
             this.durationUnit = TimeUnit.MILLISECONDS;
             this.filter = MetricFilter.ALL;
             this.ttl = null;
-            this.tags = new ArrayList<String>();
+            this.tags = new ArrayList<>();
             this.prefix = null;
             this.separator = " ";
-            try {
-                this.localHost = InetAddress.getLocalHost().getHostName();
-            } catch (UnknownHostException e) {
-                this.localHost = null;
-            }
+            this.localHost = null;
         }
 
         /**

src/main/java/com/codahale/metrics/riemann/HostnameResolution.java

@@ -0,0 +1,24 @@
+package com.codahale.metrics.riemann;
+
+import java.net.InetAddress;
+
+public enum HostnameResolution {
+    LOCAL {
+        @Override
+        public String getHostname() {
+            try {
+                return InetAddress.getLocalHost().getHostName();
+            } catch (Exception e) {
+                return null;
+            }
+        }
+    },
+    DOCKER {
+        @Override
+        public String getHostname() {
+            return System.getenv("HOST");
+        }
+    };
+
+    public abstract String getHostname();
+}

src/main/java/io/dropwizard/riemann/RiemannBundle.java

@@ -66,6 +66,7 @@ public void start() throws Exception {
                                 .tags(riemannConfig.getTags())
                                 .prefixedWith(riemannConfig.getPrefix())
                                 .useSeparator(".")
+                                .localHost(riemannConfig.getHostnameResolution().getHostname())
                                 .convertDurationsTo(TimeUnit.MILLISECONDS).convertRatesTo(TimeUnit.SECONDS);
                         riemannReporter = builder.build(riemann);
                         riemannReporter.start(riemannConfig.getPollingInterval(), TimeUnit.SECONDS);

src/main/java/io/dropwizard/riemann/RiemannConfig.java

@@ -16,11 +16,13 @@
 
 package io.dropwizard.riemann;
 
+import com.codahale.metrics.riemann.HostnameResolution;
 import lombok.*;
 import org.hibernate.validator.constraints.NotEmpty;
 
 import javax.validation.constraints.Max;
 import javax.validation.constraints.Min;
+import javax.validation.constraints.NotNull;
 import java.util.Collections;
 import java.util.List;
 
@@ -47,4 +49,7 @@ public class RiemannConfig {
 
     @Singular
     private List<String> tags = Collections.emptyList();
+
+    @NotNull
+    private HostnameResolution hostnameResolution = HostnameResolution.LOCAL;
 }