config: ProviderConfigName on Resource

config/config.go

@@ -82,6 +82,20 @@ func (r *Resource) Id() string {
 	return fmt.Sprintf("%s.%s", r.Type, r.Name)
 }
 
+// ProviderConfigName returns the name of the provider configuration in
+// the given mapping that maps to the proper provider configuration
+// for this resource.
+func (r *Resource) ProviderConfigName(pcs map[string]*ProviderConfig) string {
+	lk := ""
+	for k, _ := range pcs {
+		if strings.HasPrefix(r.Type, k) && len(k) > len(lk) {
+			lk = k
+		}
+	}
+
+	return lk
+}
+
 // ReplaceVariables replaces the variables in the configuration
 // with the given values.
 //

config/config_test.go

@@ -64,6 +64,25 @@ func TestNewUserVariable(t *testing.T) {
 	}
 }
 
+func TestResourceProviderConfigName(t *testing.T) {
+	r := &Resource{
+		Name: "foo",
+		Type: "aws_instance",
+	}
+
+	pcs := map[string]*ProviderConfig{
+		"aw":   new(ProviderConfig),
+		"aws":  new(ProviderConfig),
+		"a":    new(ProviderConfig),
+		"gce_": new(ProviderConfig),
+	}
+
+	n := r.ProviderConfigName(pcs)
+	if n != "aws" {
+		t.Fatalf("bad: %s", n)
+	}
+}
+
 func TestResourceReplaceVariables(t *testing.T) {
 	r := &Resource{
 		Name: "foo",