go-supervisor (V2)

Small library for supervising child processes in Go, it exposes Stdout,Stderr and Stdin in the "Go way" using channels...

Example

echo.sh print stuff to stdout and stderr and quit after 5 seconds...

#!/usr/bin/env bash

echo "STDOUT MESSAGE"
sleep 0.1
echo "STDERR MESSAGE" 1>&2
sleep 0.1

supervisor-exapmle.go spawn and supervise the bash program...

package main

import (
	"fmt"
	"path/filepath"
	"time"

	"github.com/kontera-technologies/go-supervisor/v2"
)

func main() {
	testDir, _ := filepath.Abs("testdata")
	events := make(chan supervisor.Event)
	p := supervisor.NewProcess(supervisor.ProcessOptions{
		Name:                 "./example.sh",
		Dir:                  testDir,
		Id:                   "example",
		EventNotifier:        events,
		OutputParser:         supervisor.MakeBytesParser,
		ErrorParser:          supervisor.MakeBytesParser,
		MaxSpawns:            4,
		MaxSpawnAttempts:     2,
		MaxInterruptAttempts: 3,
		MaxTerminateAttempts: 5,
		IdleTimeout:          10 * time.Second,
	})

	exit := make(chan bool)

	go func() {
		for {
			select {
			case msg := <-p.Stdout():
				fmt.Printf("Received STDOUT message: %s\n", *msg)
			case msg := <-p.Stderr():
				fmt.Printf("Received STDERR message: %s\n", *msg)
			case event := <-events:
				switch event.Code {
				case "ProcessStart":
					fmt.Printf("Received event: %s\n", event.Code)
				default:
					fmt.Printf("Received event: %s - %s\n", event.Code, event.Message)
				}
			case <-p.DoneNotifier():
				fmt.Println("Closing loop we are done...")
				close(exit)
				return
			}
		}
	}()

	if err := p.Start(); err != nil {
		panic(fmt.Sprintf("failed to start process: %s", err))
	}

	<-exit
}

running the program should produce this output

Received event: ProcessStart
Received STDOUT message: STDOUT MESSAGE
Received STDERR message: STDERR MESSAGE
Received event: ProcessDone - exit status 0
Received event: StoppingHeartbeatMonitoring - Stop signal received.
Received event: Sleep - Sleeping for 1s before respwaning instance.
Received event: ProcessRespawn - Trying to respawn instance.
Received event: ProcessStart
Received STDOUT message: STDOUT MESSAGE
Received STDERR message: STDERR MESSAGE
Received event: ProcessDone - exit status 0
Received event: StoppingHeartbeatMonitoring - Stop signal received.
Received event: Sleep - Sleeping for 1s before respwaning instance.
Received event: ProcessRespawn - Trying to respawn instance.
Received event: ProcessStart
Received STDOUT message: STDOUT MESSAGE
Received STDERR message: STDERR MESSAGE
Received event: ProcessDone - exit status 0
Received event: StoppingHeartbeatMonitoring - Stop signal received.
Received event: Sleep - Sleeping for 1s before respwaning instance.
Received event: ProcessRespawn - Trying to respawn instance.
Received event: ProcessStart
Received STDOUT message: STDOUT MESSAGE
Received STDERR message: STDERR MESSAGE
Received event: ProcessDone - exit status 0
Received event: StoppingHeartbeatMonitoring - Stop signal received.
Received event: RespawnError - Max number of respawns reached.
Closing loop we are done...