serverctx.go

// Package serverctx provides net/http Server
// utilities for handling context cancellation signals.
package serverctx

import (
	"context"
	"net"
	"net/http"
	"time"
)

// Run calls ListenAndServeTLS on s
// and will gracefully shut it down
// when the given ctx is done. Any
// errors will be returned whether it's
// on startup or on shutdown.
func Run(ctx context.Context, s *http.Server, timeout time.Duration) error {
	return RunTLS(ctx, s, timeout, "", "")
}

// RunTLS is like Run but calls ListenAndServeTLS instead.
func RunTLS(ctx context.Context, s *http.Server, timeout time.Duration, certFile, keyFile string) error {
	serverErr := make(chan error, 1)
	go func() {
		// Capture ListenAndServe errors such as "port already in use".
		// However, when a server is gracefully shutdown, it is safe to ignore errors
		// returned from this method (given the select logic below), because
		// Shutdown causes ListenAndServe to always return http.ErrServerClosed.
		if certFile != "" && keyFile != "" {
			serverErr <- s.ListenAndServeTLS(certFile, keyFile)
		} else {
			serverErr <- s.ListenAndServe()
		}
	}()
	var err error
	select {
	case <-ctx.Done():
		ctx, cancel := context.WithTimeout(context.Background(), timeout)
		defer cancel()
		err = s.Shutdown(ctx)
	case err = <-serverErr:
	}
	return err
}

// Serve is like Run but accepts a custom net.Listener to mimic net/http's Serve behavior.
func Serve(ctx context.Context, l net.Listener, s *http.Server, timeout time.Duration) error {
	return ServeTLS(ctx, l, s, timeout, "", "")
}

// ServeTLS is like Serve but calls ServeTLS instead.
func ServeTLS(ctx context.Context, l net.Listener, s *http.Server, timeout time.Duration, certFile, keyFile string) error {
	serverErr := make(chan error, 1)
	go func() {
		// Capture ListenAndServe errors such as "port already in use".
		// However, when a server is gracefully shutdown, it is safe to ignore errors
		// returned from this method (given the select logic below), because
		// Shutdown causes ListenAndServe to always return http.ErrServerClosed.
		if certFile != "" && keyFile != "" {
			serverErr <- s.ServeTLS(l, certFile, keyFile)
		} else {
			serverErr <- s.Serve(l)
		}
	}()
	var err error
	select {
	case <-ctx.Done():
		ctx, cancel := context.WithTimeout(context.Background(), timeout)
		defer cancel()
		err = s.Shutdown(ctx)
	case err = <-serverErr:
	}
	return err
}