compare regions against valid regions

builder/digitalocean/builder.go

@@ -35,16 +35,6 @@ func (b *Builder) Prepare(raws ...interface{}) ([]string, error) {
 	return nil, nil
 }
 
-func contains(slice []string, item string) bool {
-	set := make(map[string]struct{}, len(slice))
-	for _, s := range slice {
-		set[s] = struct{}{}
-	}
-
-	_, ok := set[item]
-	return ok
-}
-
 func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packer.Artifact, error) {
 	client := godo.NewClient(oauth2.NewClient(oauth2.NoContext, &apiTokenSource{
 		AccessToken: b.config.APIToken,
@@ -67,31 +57,14 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 			return nil, fmt.Errorf("DigitalOcean: Unable to get regions, %s", err)
 		}
 
-		var dcs []string
+		validRegions := make(map[string]struct{})
 		for _, val := range regions {
-			dcs = append(dcs, val.Slug)
-		}
-
-		regionSet := make(map[string]struct{})
-		regionsMap := make([]string, 0, len(b.config.SnapshotRegions))
-		regionSet[b.config.Region] = struct{}{}
-		for _, region := range b.config.SnapshotRegions {
-			// If we already saw the region, then don't look again
-			if _, ok := regionSet[region]; ok {
-				continue
-			}
-
-			// Mark that we saw the region
-			regionSet[region] = struct{}{}
-
-			regionsMap = append(regionsMap, region)
+			validRegions[val.Slug] = struct{}{}
 		}
 
-		for _, val := range regionsMap {
-			if contains(dcs, val) {
-				continue
-			} else {
-				return nil, fmt.Errorf("DigitalOcean: Invalid region, %s", val)
+		for _, region := range append(b.config.SnapshotRegions, b.config.Region) {
+			if _, ok := validRegions[region]; !ok {
+				return nil, fmt.Errorf("DigitalOcean: Invalid region, %s", region)
 			}
 		}
 	}