feat(constraints): Supports constraints for docker backend

docs/toml.md

@@ -203,6 +203,7 @@ Træfɪk filters services according to service attributes/tags set in your confi
 
 Supported backends:
 
+- Docker
 - Consul Catalog
 
 Supported filters:
@@ -574,6 +575,14 @@ watch = true
 #  cert = "/etc/ssl/docker.crt"
 #  key = "/etc/ssl/docker.key"
 #  insecureskipverify = true
+
+# Constraint on Docker tags
+#
+# Optional
+#
+# constraints = ["tag==api", "tag==he*ld"]
+# Matching with containers having the label "traefik.tags" set to "api,helloworld"
+# ex: $ docker run -d -P --label traefik.tags=api,helloworld emilevauge/whoami
 ```
 
 Labels can be used on containers to override default behaviour:

provider/docker.go

@@ -177,11 +177,12 @@ func (provider *Docker) loadDockerConfig(containersInspected []dockertypes.Conta
 	}
 
 	// filter containers
-	filteredContainers := fun.Filter(containerFilter, containersInspected).([]dockertypes.ContainerJSON)
+	filteredContainers := fun.Filter(provider.ContainerFilter, containersInspected).([]dockertypes.ContainerJSON)
 
 	frontends := map[string][]dockertypes.ContainerJSON{}
 	for _, container := range filteredContainers {
-		frontends[provider.getFrontendName(container)] = append(frontends[provider.getFrontendName(container)], container)
+		frontendName := provider.getFrontendName(container)
+		frontends[frontendName] = append(frontends[frontendName], container)
 	}
 
 	templateObjects := struct {
@@ -201,7 +202,8 @@ func (provider *Docker) loadDockerConfig(containersInspected []dockertypes.Conta
 	return configuration
 }
 
-func containerFilter(container dockertypes.ContainerJSON) bool {
+// ContainerFilter checks if container have to be exposed
+func (provider *Docker) ContainerFilter(container dockertypes.ContainerJSON) bool {
 	_, err := strconv.Atoi(container.Config.Labels["traefik.port"])
 	if len(container.NetworkSettings.Ports) == 0 && err != nil {
 		log.Debugf("Filtering container without port and no traefik.port label %s", container.Name)
@@ -217,6 +219,15 @@ func containerFilter(container dockertypes.ContainerJSON) bool {
 		return false
 	}
 
+	constraintTags := strings.Split(container.Config.Labels["traefik.tags"], ",")
+	ok, failingConstraint := provider.MatchConstraints(constraintTags)
+	if ok == false {
+		if failingConstraint != nil {
+			log.Debugf("Container %v pruned by '%v' constraint", container.Name, failingConstraint.String())
+		}
+		return false
+	}
+
 	return true
 }
 

provider/docker_test.go

@@ -621,6 +621,7 @@ func TestDockerGetLabels(t *testing.T) {
 }
 
 func TestDockerTraefikFilter(t *testing.T) {
+	provider := Docker{}
 	containers := []struct {
 		container docker.ContainerJSON
 		expected  bool
@@ -792,7 +793,7 @@ func TestDockerTraefikFilter(t *testing.T) {
 	}
 
 	for _, e := range containers {
-		actual := containerFilter(e.container)
+		actual := provider.ContainerFilter(e.container)
 		if actual != e.expected {
 			t.Fatalf("expected %v for %+v, got %+v", e.expected, e, actual)
 		}