Safedown

Safedown is for ensuring that an application shuts down gracefully even when termination or interruption signals are received.

Adding shutdown actions along with a set of signals allows for methods (in this case cancel) to be run when a termination signal, or similar, is received.

package main

import (
	"context"
	"syscall"
	"time"

	"github.com/Graphmasters/safedown"
)

func main() {
    defer println("Finished")
    
    // The shutdown actions are initialised and will only run
    // if one of the provided signals is received.
    sa := safedown.NewShutdownActions(safedown.FirstInLastDone, syscall.SIGTERM, syscall.SIGINT)

    // The context can be cancelled be either through the 
    // shutdown actions or via the defer.
    ctx, cancel := context.WithCancel(context.Background())
    defer cancel()
    sa.AddActions(cancel)

    println("Processing is starting")
    t := time.After(10 * time.Second)
    select {
    case <-ctx.Done():
    case <-t:
    }
}

To ensure that the shutdown logic (represented by actions) always runs (particularly for running unending applications) one can also include the line defer sa.Shutdown().

package main

import (
	"context"
	"syscall"
	"time"

	"github.com/Graphmasters/safedown"
)

func main() {
    defer println("Finished")

    // The shutdown actions are initialised and Shutdown is
    // deferred. This ensures that the shutdown actions are
    // always run and that the main is blocked from 
    // finishing until the shutdown process is complete.
    sa := safedown.NewShutdownActions(safedown.FirstInLastDone, syscall.SIGTERM, syscall.SIGINT)
    defer sa.Shutdown()

    // The context can be cancelled be through the shutdown
    // action, triggered either by a signal or sa.Shutdown().
    ctx, cancel := context.WithCancel(context.Background())
    sa.AddActions(cancel)

    println("Processing is starting")
    t := time.After(10 * time.Second)
    select {
    case <-ctx.Done():
    case <-t:
    }
}

One can also manage shutdown actions across goroutines by creating the shutdown actions without any signals to be listened for.

Additional examples can be found in the examples module

1. HTTP server with database.

F.A.Q.

• How do I ensure that the shutdown actions complete before the program terminates? Use either Shutdown() or Wait(). We recommend against using Wait() as it is possible the shutdown actions will never be triggered and the program will never stop.