feat: validate remaining unsupported items of the support-matrix (#429)

* feat: validate remaining unsupported items of the support-matrix

Validate unsupported compose features: external configs, container_name,
and placement.

This makes the code match the support-matrix as of now (added comment to
that effect as well).

Signed-off-by: Miek Gieben <miek@miek.nl>

* support matrix: some deploy modes are supported

Add tests for the various non-supported deploy modes.
Prefix the warnings with `deploy ` to signal the section, and to
differentiate between top level 'labels' and 'deploy labels'.

Signed-off-by: Miek Gieben <miek@miek.nl>

---------

Signed-off-by: Miek Gieben <miek@miek.nl>

pkg/client/compose/service.go

@@ -454,13 +454,22 @@ func validateServicesExtensions(project *types.Project) error {
 
 // validateServicesFeatures checks services for unsupported features and returns all found.
 func validateServicesFeatures(project *types.Project) []error {
-	err := func(service, feature string) error {
-		return fmt.Errorf("service '%s': unsupported feature '%s', see %s",
-			service, feature, "https://uncloud.run/docs/compose-file-reference/support-matrix")
+	// XXX(miek): as of Sep 2026 these checks are in check with the support-matrix, except for a short syntax
+	// check.
+	var errs []error
+	const supportmatrix = "https://uncloud.run/docs/compose-file-reference/support-matrix"
+
+	for _, config := range project.Configs {
+		if config.External {
+			errs = append(errs, fmt.Errorf("config '%s': unsupported feature '%s', see %s",
+				config.Name, "external", supportmatrix))
+		}
 	}
 
-	// TODO: check other commonly used but unsupported features.
-	var errs []error
+	err := func(service, feature string) error {
+		return fmt.Errorf("service '%s': unsupported feature '%s', see %s",
+			service, feature, supportmatrix)
+	}
 	for _, service := range project.Services {
 		if service.SecurityOpt != nil {
 			errs = append(errs, err(service.Name, "security_opt"))
@@ -489,6 +498,32 @@ func validateServicesFeatures(project *types.Project) []error {
 		if service.StorageOpt != nil {
 			errs = append(errs, err(service.Name, "storage_opt"))
 		}
+		if service.ContainerName != "" {
+			errs = append(errs, err(service.Name, "container_name"))
+		}
+		if service.Deploy != nil {
+			if len(service.Deploy.Placement.Constraints) > 0 || len(service.Deploy.Placement.Preferences) > 0 {
+				errs = append(errs, fmt.Errorf(
+					"service '%s': deploy placement is not supported, "+
+						"use x-machines instead: %s", service.Name,
+					"https://uncloud.run/docs/compose-file-reference/extensions#x-machines"))
+			}
+
+			if service.Deploy.RestartPolicy != nil {
+				errs = append(errs, fmt.Errorf(
+					"service '%s': deploy restart_policy defaults to 'unless-stopped'", service.Name))
+			}
+			if service.Deploy.Mode != "" && service.Deploy.Mode != "global" && service.Deploy.Mode != "replicated" {
+				errs = append(errs, fmt.Errorf(
+					"service '%s': deploy mode must either be 'global' or 'replicated'", service.Name))
+			}
+			if service.Deploy.RollbackConfig != nil {
+				errs = append(errs, err(service.Name, "deploy rollback_config"))
+			}
+			if len(service.Deploy.Labels) != 0 {
+				errs = append(errs, err(service.Name, "deploy labels"))
+			}
+		}
 		// we only allow the 'default' network, nothing else.
 		if x := service.Networks; x != nil {
 			if len(x) != 1 {