azurerm_container_app - Add validations for the ingress.0.traffic_weight

internal/services/containerapps/container_app_resource.go

@@ -409,7 +409,51 @@ func (r ContainerAppResource) Update() sdk.ResourceFunc {
 func (r ContainerAppResource) CustomizeDiff() sdk.ResourceFunc {
 	return sdk.ResourceFunc{
 		Func: func(ctx context.Context, metadata sdk.ResourceMetaData) error {
-			if metadata.ResourceDiff != nil && metadata.ResourceDiff.HasChange("secret") {
+			if metadata.ResourceDiff == nil {
+				return nil
+			}
+			var app ContainerAppModel
+			if err := metadata.DecodeDiff(&app); err != nil {
+				return err
+			}
+			// Ingress traffic weight validations
+			if len(app.Ingress) != 0 {
+				ingress := app.Ingress[0]
+				if metadata.ResourceDiff.HasChange("name") {
+					// Validation for create time
+					// (Above is a trick to tell whether this is for a new create apply, as the "name" is a force new property)
+					if len(ingress.TrafficWeights) != 0 {
+						if len(ingress.TrafficWeights) > 1 {
+							return fmt.Errorf("at most one `ingress.0.traffic_weight` can be specified during creation")
+						}
+						tw := ingress.TrafficWeights[0]
+						if !tw.LatestRevision {
+							return fmt.Errorf("`ingress.0.traffic_weight.0.latest_revision` must be set to true during creation")
+						}
+						if tw.RevisionSuffix != "" {
+							return fmt.Errorf("`ingress.0.traffic_weight.0.revision_suffix` must not be set during creation")
+						}
+					}
+				} else {
+					// Validation for update time
+					var latestRevCount int
+					for i, tw := range ingress.TrafficWeights {
+						if tw.LatestRevision {
+							latestRevCount++
+							if tw.RevisionSuffix != "" {
+								return fmt.Errorf("`ingress.0.traffic_weight.%[1]d.revision_suffix` conflicts with `ingress.0.traffic_weight.%[1]d.latest_revision`", i)
+							}
+						} else if tw.RevisionSuffix == "" {
+							return fmt.Errorf("`ingress.0.traffic_weight.%[1]d.revision_suffix` is not specified", i)
+						}
+					}
+					if latestRevCount > 1 {
+						return fmt.Errorf("more than one `ingress.0.traffic_weight` has `latest_revision` set to `true`")
+					}
+				}
+			}
+
+			if metadata.ResourceDiff.HasChange("secret") {
 				stateSecretsRaw, configSecretsRaw := metadata.ResourceDiff.GetChange("secret")
 				stateSecrets := stateSecretsRaw.(*schema.Set).List()
 				configSecrets := configSecretsRaw.(*schema.Set).List()