remove constraint for container_name unicity while loading model

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

loader/validate.go

@@ -28,7 +28,6 @@ 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)
@@ -145,13 +144,6 @@ func checkConsistency(project *types.Project) error {
 			}
 		}
 
-		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

@@ -17,7 +17,6 @@
 package loader
 
 import (
-	"strings"
 	"testing"
 
 	"gotest.tools/v3/assert"
@@ -261,25 +260,6 @@ func TestValidateDependsOn(t *testing.T) {
 	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.Assert(t, strings.Contains(err.Error(), `container name "mycontainer" is already in use by`))
-}
-
 func TestValidateWatch(t *testing.T) {
 	t.Run("watch valid configuration", func(t *testing.T) {
 		project := types.Project{

types/project.go

@@ -696,3 +696,17 @@ func (p *Project) WithServicesTransform(fn func(name string, s ServiceConfig) (S
 	}
 	return newProject, eg.Wait()
 }
+
+// CheckContainerNameUnicity validate project doesn't have services declaring the same container_name
+func (p *Project) CheckContainerNameUnicity() error {
+	names := utils.Set[string]{}
+	for name, s := range p.Services {
+		if s.ContainerName != "" {
+			if existing, ok := names[s.ContainerName]; ok {
+				return fmt.Errorf(`services.%s: container name %q is already in use by service %s"`, name, s.ContainerName, existing)
+			}
+			names.Add(s.ContainerName)
+		}
+	}
+	return nil
+}