client builder with token producer; allow reload of new token after i…

src/main/java/com/orbitz/consul/Consul.java

@@ -21,6 +21,7 @@
 import com.orbitz.consul.cache.TimeoutInterceptor;
 import com.orbitz.consul.config.ClientConfig;
 import com.orbitz.consul.monitoring.ClientEventCallback;
+import com.orbitz.consul.util.AuthTokenProducer;
 import com.orbitz.consul.util.Jackson;
 import com.orbitz.consul.util.TrustManagerUtils;
 import com.orbitz.consul.util.bookend.ConsulBookend;
@@ -392,6 +393,28 @@ public Builder withTokenAuth(String token) {
             return this;
         }
 
+
+        /**
+         * Sets the token used for authentication
+         *
+         * @param authTokenProducer the producer of the authentication token
+         * @return The builder.
+         */
+        public Builder withTokenAuth(AuthTokenProducer authTokenProducer) {
+            authInterceptor = chain -> {
+                Request original = chain.request();
+
+                Request.Builder requestBuilder = original.newBuilder()
+                        .header("X-Consul-Token", authTokenProducer.getToken())
+                        .method(original.method(), original.body());
+
+                Request request = requestBuilder.build();
+                return chain.proceed(request);
+            };
+
+            return this;
+        }
+
         /**
         * Sets the ACL token to be used with Consul
         *

src/main/java/com/orbitz/consul/util/AuthTokenProducer.java

@@ -0,0 +1,7 @@
+package com.orbitz.consul.util;
+
+public interface AuthTokenProducer {
+
+    String getToken();
+
+}