Policing up the new tags code from @Carles-Figuerola

Just some cosmetics and some cleaning up to make the code fit in a
little better with the existing code. Functionally no changes are made
and the existing tests still pass.

builtin/providers/cloudstack/resource_cloudstack_network.go

@@ -178,7 +178,7 @@ func resourceCloudStackNetworkCreate(d *schema.ResourceData, meta interface{}) e
 
 	err = setTags(cs, d, "network")
 	if err != nil {
-		return fmt.Errorf("Error setting tags")
+		return fmt.Errorf("Error setting tags: %s", err)
 	}
 
 	return resourceCloudStackNetworkRead(d, meta)
@@ -206,7 +206,7 @@ func resourceCloudStackNetworkRead(d *schema.ResourceData, meta interface{}) err
 	d.Set("gateway", n.Gateway)
 
 	// Read the tags and store them in a map
-	tags := make(map[string]string)
+	tags := make(map[string]interface{})
 	for item := range n.Tags {
 		tags[n.Tags[item].Key] = n.Tags[item].Value
 	}
@@ -262,9 +262,11 @@ func resourceCloudStackNetworkUpdate(d *schema.ResourceData, meta interface{}) e
 	}
 
 	// Update tags if they have changed
-	err = setTags(cs, d, "network")
-	if err != nil {
-		return fmt.Errorf("Error updating tags")
+	if d.HasChange("tags") {
+		err = setTags(cs, d, "network")
+		if err != nil {
+			return fmt.Errorf("Error updating tags: %s", err)
+		}
 	}
 
 	return resourceCloudStackNetworkRead(d, meta)

builtin/providers/cloudstack/resource_cloudstack_network_test.go

@@ -163,13 +163,13 @@ func testAccCheckCloudStackNetworkDestroy(s *terraform.State) error {
 
 var testAccCloudStackNetwork_basic = fmt.Sprintf(`
 resource "cloudstack_network" "foo" {
-  name = "terraform-network"
-  cidr = "%s"
-  network_offering = "%s"
-  zone = "%s"
-  tags = {
-	terraform-tag = "true"
-  }
+	name = "terraform-network"
+	cidr = "%s"
+	network_offering = "%s"
+	zone = "%s"
+	tags = {
+		terraform-tag = "true"
+	}
 }`,
 	CLOUDSTACK_NETWORK_2_CIDR,
 	CLOUDSTACK_NETWORK_2_OFFERING,
@@ -184,11 +184,11 @@ resource "cloudstack_vpc" "foobar" {
 }
 
 resource "cloudstack_network" "foo" {
-  name = "terraform-network"
-  cidr = "%s"
-  network_offering = "%s"
-  vpc = "${cloudstack_vpc.foobar.name}"
-  zone = "${cloudstack_vpc.foobar.zone}"
+	name = "terraform-network"
+	cidr = "%s"
+	network_offering = "%s"
+	vpc = "${cloudstack_vpc.foobar.name}"
+	zone = "${cloudstack_vpc.foobar.zone}"
 }`,
 	CLOUDSTACK_VPC_CIDR_1,
 	CLOUDSTACK_VPC_OFFERING,

builtin/providers/cloudstack/tags.go

@@ -7,72 +7,67 @@ import (
 	"github.com/xanzy/go-cloudstack/cloudstack"
 )
 
-// tagsSchema returns the schema to use for tags.
-//
+// tagsSchema returns the schema to use for tags
 func tagsSchema() *schema.Schema {
 	return &schema.Schema{
 		Type:     schema.TypeMap,
 		Optional: true,
+		Computed: true,
 	}
 }
 
 // setTags is a helper to set the tags for a resource. It expects the
 // tags field to be named "tags"
 func setTags(cs *cloudstack.CloudStackClient, d *schema.ResourceData, resourcetype string) error {
-	if d.HasChange("tags") {
-		oraw, nraw := d.GetChange("tags")
-		o := oraw.(map[string]interface{})
-		n := nraw.(map[string]interface{})
-		create, remove := diffTags(tagsFromSchema(o), tagsFromSchema(n))
-		log.Printf("[DEBUG] tags to remove: %v", remove)
-		log.Printf("[DEBUG] tags to create: %v", create)
+	oraw, nraw := d.GetChange("tags")
+	o := oraw.(map[string]interface{})
+	n := nraw.(map[string]interface{})
 
-		// Set tags
-		if len(remove) > 0 {
-			log.Printf("[DEBUG] Removing tags: %v from %s", remove, d.Id())
-			p := cs.Resourcetags.NewDeleteTagsParams([]string{d.Id()}, resourcetype)
-			p.SetTags(remove)
-			_, err := cs.Resourcetags.DeleteTags(p)
-			if err != nil {
-				return err
-			}
+	remove, create := diffTags(tagsFromSchema(o), tagsFromSchema(n))
+	log.Printf("[DEBUG] tags to remove: %v", remove)
+	log.Printf("[DEBUG] tags to create: %v", create)
+
+	// First remove any obsolete tags
+	if len(remove) > 0 {
+		log.Printf("[DEBUG] Removing tags: %v from %s", remove, d.Id())
+		p := cs.Resourcetags.NewDeleteTagsParams([]string{d.Id()}, resourcetype)
+		p.SetTags(remove)
+		_, err := cs.Resourcetags.DeleteTags(p)
+		if err != nil {
+			return err
 		}
-		if len(create) > 0 {
-			log.Printf("[DEBUG] Creating tags: %v for %s", create, d.Id())
-			p := cs.Resourcetags.NewCreateTagsParams([]string{d.Id()}, resourcetype, create)
-			_, err := cs.Resourcetags.CreateTags(p)
-			if err != nil {
-				return err
-			}
+	}
+
+	// Then add any new tags
+	if len(create) > 0 {
+		log.Printf("[DEBUG] Creating tags: %v for %s", create, d.Id())
+		p := cs.Resourcetags.NewCreateTagsParams([]string{d.Id()}, resourcetype, create)
+		_, err := cs.Resourcetags.CreateTags(p)
+		if err != nil {
+			return err
 		}
 	}
 
 	return nil
 }
 
-// diffTags takes our tags locally and the ones remotely and returns
-// the set of tags that must be destroyed, and the set of tags that must
-// be created.
+// diffTags takes the old and the new tag sets and returns the difference of
+// both. The remaining tags are those that need to be removed and created
 func diffTags(oldTags, newTags map[string]string) (map[string]string, map[string]string) {
-	remove := make(map[string]string)
-	for k, v := range oldTags {
-		old, ok := newTags[k]
-		if !ok || old != v {
-			// Delete it!
-			remove[k] = v
-		} else {
-			// We need to remove the modified tags to create them again,
-			// but we should avoid creating what we already have
+	for k, old := range oldTags {
+		new, ok := newTags[k]
+		if ok && old == new {
+			// We should avoid removing or creating tags we already have
+			delete(oldTags, k)
 			delete(newTags, k)
 		}
 	}
 
-	return newTags, remove
+	return oldTags, newTags
 }
 
-// tagsFromSchema returns the tags for the given tags schema.
-// It's needed to properly unpack all string:interface types
-// to a proper string:string map
+// tagsFromSchema takes the raw schema tags and returns them as a
+// properly asserted map[string]string
 func tagsFromSchema(m map[string]interface{}) map[string]string {
 	result := make(map[string]string, len(m))
 	for k, v := range m {

builtin/providers/cloudstack/tags_test.go

@@ -45,27 +45,21 @@ func TestDiffTags(t *testing.T) {
 	}
 
 	for i, tc := range cases {
-		c, r := diffTags(tagsFromSchema(tc.Old), tagsFromSchema(tc.New))
-		if !reflect.DeepEqual(c, tc.Create) {
-			t.Fatalf("%d: bad create: %#v", i, c)
-		}
+		r, c := diffTags(tagsFromSchema(tc.Old), tagsFromSchema(tc.New))
 		if !reflect.DeepEqual(r, tc.Remove) {
 			t.Fatalf("%d: bad remove: %#v", i, r)
 		}
+		if !reflect.DeepEqual(c, tc.Create) {
+			t.Fatalf("%d: bad create: %#v", i, c)
+		}
 	}
 }
 
 // testAccCheckTags can be used to check the tags on a resource.
-func testAccCheckTags(
-	tags map[string]string, key string, value string) error {
+func testAccCheckTags(tags map[string]string, key string, value string) error {
 	v, ok := tags[key]
-	if value != "" && !ok {
+	if !ok {
 		return fmt.Errorf("Missing tag: %s", key)
-	} else if value == "" && ok {
-		return fmt.Errorf("Extra tag: %s", key)
-	}
-	if value == "" {
-		return nil
 	}
 
 	if v != value {