Fix cannot retry upgrade gsk when previous upgrade fails v1 (#410)

* always get template uuid from version/release even if version/release is not changed

IF the previous upgrade (from 1.29 to 1.30) fails, the updated value of version/release is still persisted (tf provider behaviour because we don't set version/release in k8s resource READ). Hence when we re-try the upgrade, this piece of code detects no changes in version/release parameter => tf tries to get template uuid from service_template_uuid (which is just the current template of the cluster), hence no upgrade happens.

* refresh gsk version/release on read

gridscale/resource_gridscale_k8s.go

@@ -374,30 +374,18 @@ func deriveK8sTemplateFromResourceData(client *gsclient.Client, d *schema.Resour
 	releaseInterface, isReleaseSet := d.GetOk("release")
 	release := releaseInterface.(string)
 
-	if !d.IsNewResource() { // case if update of resource is requested
-		if isVersionSet && d.HasChange("version") {
-			derivationTypesRequested += 1
-			derivationType = "version"
-		}
-
-		if isReleaseSet && d.HasChange("release") {
-			derivationTypesRequested += 1
-			derivationType = "release"
-		}
-	} else { // case if creation of resource is requested
-		if isVersionSet {
-			derivationTypesRequested += 1
-			derivationType = "version"
-		}
+	if isVersionSet {
+		derivationTypesRequested += 1
+		derivationType = "version"
+	}
 
-		if isReleaseSet {
-			derivationTypesRequested += 1
-			derivationType = "release"
-		}
+	if isReleaseSet {
+		derivationTypesRequested += 1
+		derivationType = "release"
+	}
 
-		if derivationTypesRequested == 0 {
-			return nil, errors.New("either \"release\" or \"gsk_version\" has to be defined")
-		}
+	if derivationTypesRequested == 0 {
+		return nil, errors.New("either \"release\" or \"gsk_version\" has to be defined")
 	}
 
 	if derivationTypesRequested > 1 {
@@ -553,6 +541,22 @@ func resourceGridscaleK8sRead(d *schema.ResourceData, meta interface{}) error {
 			return fmt.Errorf("%s error setting kubeconfig: %v", errorPrefix, err)
 		}
 	}
+	template, err := deriveK8sTemplateFromUUID(client, props.ServiceTemplateUUID)
+	if err != nil {
+		return fmt.Errorf("%s error: %v", errorPrefix, err)
+	}
+	// if version is set, set it with the version of the template
+	if _, isVersionSet := d.GetOk("gsk_version"); isVersionSet {
+		if err = d.Set("gsk_version", template.Properties.Version); err != nil {
+			return fmt.Errorf("%s error setting gsk_version: %v", errorPrefix, err)
+		}
+	}
+	// if release is set, set it with the release of the template
+	if _, isReleaseSet := d.GetOk("release"); isReleaseSet {
+		if err = d.Set("release", template.Properties.Release); err != nil {
+			return fmt.Errorf("%s error setting release: %v", errorPrefix, err)
+		}
+	}
 	if err = d.Set("security_zone_uuid", props.SecurityZoneUUID); err != nil {
 		return fmt.Errorf("%s error setting security_zone_uuid: %v", errorPrefix, err)
 	}