providers/aws: style nitpick

builtin/providers/aws/config.go

@@ -76,8 +76,8 @@ func (c *Config) Client() (interface{}, error) {
 		client.region = c.Region
 
 		log.Println("[INFO] Building AWS auth structure")
-		// We fetched all credential sources in Provider.
-		// If it is available, it is stored in c.
+		// We fetched all credential sources in Provider. If they are
+		// available, they'll already be in c. See Provider definition.
 		creds := credentials.NewStaticCredentials(c.AccessKey, c.SecretKey, c.Token)
 		awsConfig := &aws.Config{
 			Credentials: creds,

builtin/providers/aws/provider.go

@@ -14,21 +14,28 @@ func Provider() terraform.ResourceProvider {
 	// TODO: Move the validation to this, requires conditional schemas
 	// TODO: Move the configuration to this, requires validation
 
-	// Prepare to handle external sources of credentials.
-	// Static credentials are intentionally omitted;
-	// this is used when no static credentials are provided.
+	// These variables are closed within the `getCreds` function below.
+	// This function is responsible for reading credentials from the
+	// environment in the case that they're not explicitly specified
+	// in the Terraform configuration.
+	//
+	// By using the getCreds function here instead of making the default
+	// empty, we avoid asking for input on credentials if they're available
+	// in the environment.
+	var credVal credentials.Value
+	var credErr error
+	var once sync.Once
+	getCreds := func() {
 		creds := credentials.NewChainCredentials([]credentials.Provider{
 			&credentials.EnvProvider{},
 			&credentials.SharedCredentialsProvider{},
 			&credentials.EC2RoleProvider{},
 		})
-	var credVal credentials.Value
-	var credErr error
-	var once sync.Once
-	getCreds := func() {
+
 		credVal, credErr = creds.Get()
 	}
 
+	// The actual provider
 	return &schema.Provider{
 		Schema: map[string]*schema.Schema{
 			"access_key": &schema.Schema{