Golang catch sigterm and continue application

Question

Is it possible to catch a sigterm in Golang and move on on the code, like a panic/defer?

Example:

func main() {
    fmt.Println("app started")
    setupGracefulShutdown()

    for {
    }
    close()    
}

func close() {
    fmt.Println("infinite loop stopped and got here")
}

func setupGracefulShutdown() {
    sigChan := make(chan os.Signal)
    signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)

    go func() {
        fmt.Println(" got interrupt signal: ", <-sigChan)
    }()
}

// "app started"
// CTRL + C
// ^C "got interrupt signal:  interrupt"
// app don't stop

What I want is to print infinite loop stopped and got here and finish application.

// "app started"
// CTRL + C
// ^C "got interrupt signal:  interrupt"
// "infinite loop stopped and got here"

Retiary

Your "infinite" loop could monitor the sigChan and "break" once a value is received from it. What's wrong with that? – Hamrick

Side note: make a chan with cap 1 for your signals. – Clancy

The example is for visualisation only, I have no control over the infinite loop, I'm trying to implement this on an internal library. – Retiary

Answer 1

This is very easy to achieve. Because the signal channel needs to block and wait for a signal, you have to start your business logic code in a different goroutine.

func main() {
    cancelChan := make(chan os.Signal, 1)
    // catch SIGETRM or SIGINTERRUPT
    signal.Notify(cancelChan, syscall.SIGTERM, syscall.SIGINT)
    go func() {
        // start your software here. Maybe your need to replace the for loop with other code
        for {
            // replace the time.Sleep with your code
            log.Println("Loop tick")
            time.Sleep(time.Second)
        }
    }()
    sig := <-cancelChan
    log.Printf("Caught signal %v", sig)
    // shutdown other goroutines gracefully
    // close other resources
}

Mita