Fetching contributors…
Cannot retrieve contributors at this time
86 lines (73 sloc) 2.4 KB
// Copyright © 2016 Asteris, LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package resource
import ""
// Tasker is a struct that is or contains an embedded resource.Task and a
// resource.Status. It's implemented by plan.Result and apply.Result
type Tasker interface {
GetTask() (Task, bool)
GetStatus() TaskStatus
// Task controls checks and application inside the system. Check will be called
// first; if it indicates changes will be made then Apply will also be called.
// Check will be called again if Apply succeeds with no error to get the final
// status of the resource.
type Task interface {
Check(context.Context, Renderer) (TaskStatus, error)
Apply(context.Context) (TaskStatus, error)
// Resource adds metadata about the executed tasks
type Resource interface {
Prepare(context.Context, Renderer) (Task, error)
// Value is anything that can be in a renderer's Value
type Value interface{}
// Renderer is passed to resources
type Renderer interface {
GetID() string
Value() (value Value, present bool)
Render(name, content string) (string, error)
// TaskWrapper provides an implementation of render.Tasker for tasks
type TaskWrapper struct {
// GetTask provides Tasker.GetTask ontop of a task
func (t *TaskWrapper) GetTask() (Task, bool) {
return t.Task, true
// GetStatus returns a nil status for a wrapped task
func (t *TaskWrapper) GetStatus() TaskStatus {
return nil
// WrapTask creates a new TaskWrapper
func WrapTask(t Task) *TaskWrapper {
return &TaskWrapper{t}
// ResolveTask unwraps Tasker layers until it finds an underlying Task or fails
func ResolveTask(w interface{}) (Task, bool) {
if w == nil {
return nil, false
if tasker, ok := w.(Tasker); ok {
taskerTask, found := tasker.GetTask()
if !found {
return nil, false
return ResolveTask(taskerTask)
} else if task, ok := w.(Task); ok {
return task, true
return nil, false