check that a container_name is used only once across all services dec…

…larations

Signed-off-by: Guillaume Lours <[email protected]>

loader/validate.go

@@ -29,6 +29,7 @@ import (
 
 // checkConsistency validate a compose model is consistent
 func checkConsistency(project *types.Project) error {
+	containerNames := map[string]string{}
 	for _, s := range project.Services {
 		if s.Build == nil && s.Image == "" {
 			return fmt.Errorf("service %q has neither an image nor a build context specified: %w", s.Name, errdefs.ErrInvalid)
@@ -123,6 +124,13 @@ func checkConsistency(project *types.Project) error {
 			s.Deploy.Replicas = s.Scale
 		}
 
+		if s.ContainerName != "" {
+			if existing, ok := containerNames[s.ContainerName]; ok {
+				return fmt.Errorf(`"services.%s": container name "%s" is already in use by "services.%s": %w`, s.Name, s.ContainerName, existing, errdefs.ErrInvalid)
+			}
+			containerNames[s.ContainerName] = s.Name
+		}
+
 		if s.GetScale() > 1 && s.ContainerName != "" {
 			attr := "scale"
 			if s.Scale == nil {

loader/validate_test.go

@@ -259,3 +259,22 @@ func TestValidateDependsOn(t *testing.T) {
 	err := checkConsistency(&project)
 	assert.Error(t, err, `service "myservice" depends on undefined service missingservice: invalid compose project`)
 }
+
+func TestValidateContainerName(t *testing.T) {
+	project := types.Project{
+		Services: types.Services{
+			"myservice": {
+				Name:          "myservice",
+				Image:         "scratch",
+				ContainerName: "mycontainer",
+			},
+			"myservice2": {
+				Name:          "myservice2",
+				Image:         "scratch",
+				ContainerName: "mycontainer",
+			},
+		},
+	}
+	err := checkConsistency(&project)
+	assert.Error(t, err, `"services.myservice2": container name "mycontainer" is already in use by "services.myservice": invalid compose project`)
+}