Support listing services by label (fixes spotify#615)

src/main/java/com/spotify/docker/client/DefaultDockerClient.java

@@ -121,11 +121,13 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.regex.Pattern;
@@ -1675,7 +1677,6 @@ public List<Service> listServices() throws DockerException, InterruptedException
   public List<Service> listServices(final Service.Criteria criteria)
       throws DockerException, InterruptedException {
     assertApiVersionIsAbove("1.24");
-    WebTarget resource = resource().path("services");
     final Map<String, List<String>> filters = new HashMap<>();
 
     if (criteria.serviceId() != null) {
@@ -1685,6 +1686,20 @@ public List<Service> listServices(final Service.Criteria criteria)
       filters.put("name", Collections.singletonList(criteria.serviceName()));
     }
 
+    final List<String> labels = new ArrayList<>();
+    for (Entry<String, String> input: criteria.labels().entrySet()) {
+      if ("".equals(input.getValue())) {
+        labels.add(input.getKey());
+      } else {
+        labels.add(String.format("%s=%s", input.getKey(), input.getValue()));
+      }
+    }
+
+    if (!labels.isEmpty()) {
+      filters.put("label", labels);
+    }
+
+    WebTarget resource = resource().path("services");
     resource = resource.queryParam("filters", urlEncodeFilters(filters));
     return request(GET, SERVICE_LIST, resource, resource.request(APPLICATION_JSON_TYPE));
   }

src/main/java/com/spotify/docker/client/messages/swarm/Service.java

@@ -27,8 +27,11 @@
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableMap;
 
 import java.util.Date;
+import java.util.Map;
+
 import javax.annotation.Nullable;
 
 @AutoValue
@@ -71,6 +74,12 @@ public abstract static class Criteria {
     @Nullable
     public abstract String serviceName();
 
+    /**
+     * Filter by label.
+     */
+    @Nullable
+    public abstract ImmutableMap<String, String> labels();
+
     public static Builder builder() {
       return new AutoValue_Service_Criteria.Builder();
     }
@@ -100,6 +109,15 @@ public Builder withServiceName(final String serviceName) {
         return this;
       }
 
+      public abstract Builder labels(final Map<String, String> labels);
+
+      abstract ImmutableMap.Builder<String, String> labelsBuilder();
+
+      public Builder addLabel(final String label, final String value) {
+        labelsBuilder().put(label, value);
+        return this;
+      }
+
       public abstract Criteria build();
     }
   }

src/test/java/com/spotify/docker/client/DefaultDockerClientTest.java

@@ -4210,6 +4210,27 @@ public void testListServicesFilterByName() throws Exception {
     assertThat(services.size(), is(1));
     assertThat(services.get(0).spec().name(), is(serviceName));
   }
+
+  @Test
+  public void testListServicesFilterByLabel() throws Exception {
+    requireDockerApiVersionAtLeast("1.24", "swarm support");
+    final String serviceName = randomName();
+
+    Map<String, String> labels = new HashMap<>();
+    labels.put("foo", "bar");
+
+    final ServiceSpec spec = createServiceSpec(serviceName, labels);
+    sut.createService(spec);
+
+    final List<Service> services = sut.listServices(Service.find().addLabel("foo", "bar").build());
+
+    assertThat(services.size(), is(1));
+    assertThat(services.get(0).spec().labels().get("foo"), is("bar"));
+
+    final List<Service> notFoundServices = sut.listServices(Service.find()
+        .addLabel("bar", "foo").build());
+    assertThat(notFoundServices.size(), is(0));
+  }
 
   @Test
   public void testRemoveService() throws Exception {
@@ -4264,6 +4285,12 @@ public void testListTaskWithCriteria() throws Exception {
   }
 
   private ServiceSpec createServiceSpec(final String serviceName) {
+    return this.createServiceSpec(serviceName, new HashMap<String, String>());
+  }
+
+  private ServiceSpec createServiceSpec(final String serviceName, 
+      final Map<String, String> labels) {
+
     final TaskSpec taskSpec = TaskSpec
         .builder()
         .containerSpec(ContainerSpec.builder().image("alpine")
@@ -4274,6 +4301,7 @@ private ServiceSpec createServiceSpec(final String serviceName) {
 
     return ServiceSpec.builder().name(serviceName).taskTemplate(taskSpec)
         .mode(serviceMode)
+        .labels(labels)
         .build();
   }