Runnable

Tooling to manage the execution of a process based on a Runnable interface:

type Runnable interface {
	Run(context.Context) error
}

And a simpler RunnableFunc interface:

type RunnableFunc func(context.Context) error

Example of an implementation of the command "yes":

func main() {
	runnable.RunFunc(run)
}

func run(ctx context.Context) error {
	for {
		if ctx.Err() != nil {
			return ctx.Err()
		}
		fmt.Println("y")
	}
}

Tools:

• Process start and shutdown
• Restart
• HTTP Server
• Dependency Manager

Process start and shutdown

To trigger a clean shutdown, a process must react to the termination signals (SIGINT, SIGTERM).

The Run() method is intended to be the process entrypoint:

• it immediately executes the runnable
• it cancels the context.Context when a termination signal is received
• it calls log.Fatal with the error if the runnable returned one

Example:

func main() {
	runnable.Run(
		app.Build(),
	)
}

The RunFunc() method is also provided for convenience.

Restart

The Restart runnable ensure that a component is running, even if it stops or crashes.

Example:

func main() {
	runnable.Run(
		runnable.Restart(
			task.New(),
		),
	)
}

HTTP Server

The HTTPServer runnable starts and gracefully shutdowns a *http.Server.

Example:

func main() {
	server := &http.Server{
		Addr:    "127.0.0.1:8000",
		Handler: http.RedirectHandler("https://go.dev", 307),
	}

	runnable.Run(
		runnable.HTTPServer(server),
	)
}

Dependency Manager

The Manager runnable starts and stops all runnables while respecting the dependency between them. Components with dependencies will be stopped before their dependencies.

Example with three components:

g := runnable.Manager(nil)
g.Add(jobQueue)
g.Add(httpServer, jobQueue) // jobs is a dependency
g.Add(monitor)

runnable.Run(g.Build())

Logs of a demo app

$ go run ./cmd/example
[RUNNABLE] 2020/10/22 22:42:26 INFO manager: main.JobQueue started
[RUNNABLE] 2020/10/22 22:42:26 INFO manager: runnable.httpServer started
[RUNNABLE] 2020/10/22 22:42:26 INFO manager: main.Monitor started
...
^C[RUNNABLE] 2020/10/22 22:42:34 INFO signal: received signal interrupt
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: starting shutdown (context cancelled)
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: runnable.httpServer cancelled
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: main.Monitor cancelled
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: main.Monitor stopped
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: runnable.httpServer stopped
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: main.JobQueue cancelled
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: main.JobQueue stopped
[RUNNABLE] 2020/10/22 22:42:34 INFO manager: shutdown complete

License

The MIT License (MIT)