Gracefully shutdown Go API server connected to Database.

Go offers scalable and robust mechanism for creating API servers. As most of APIs talk to some database, on a scaled infrastructure receiving a lot of requests per second, it is important to shutdown gracefully in order to prevent goroutine leaks.

This means closing two things in our case:

1. HTTP Server

2. DB connection

Go net/http package offers Shutdown function to gracefully shutdown your http server. https://godoc.org/net/http#Server.Shutdown.

Go database/sql package offers Close function to gracefully close the connection to sql. https://godoc.org/database/sql#DB.Close

1) Create a minimal HTTP API service using a Database

2) Change your server function “srv.ListenAndServe()” to run in a goroutine

go func() {
    panic(srv.ListenAndServe())
}()

This is done to ensure that main will not exit when srv.ListenAndServe() returns on stop signal and waits for database to be closed. Note that we’re using panic rather than log.Fatal to capture errors from srv.ListenAndServe() in order to be able to call defer in next steps.

3) Create a channel to receive stop signals

stop := make(chan os.Signal, 1)
signal.Notify(stop, os.Interrupt)
signal.Notify(stop, syscall.SIGTERM)

Bonus point: If you’re using kubernetes, note that it sends SIGTERM signal to its pods for shutting down. Interrupt is normally sent

4) Listen to the stop signals and handle the shutdown of your HTTP Server

You can use defer to close your db connection.

<-stop

Note: We are shutting down HTTP server before closing db because server will need database to handle its API requests.