Handle SIGTERM gracefully about boulder HOT 2 CLOSED

// Starts the AMQP-RPC server running in a separate thread.
// There is currently no Stop() method.
func (rpc *AmqpRPCServer) Start() (err error) {
    msgs, err := amqpSubscribe(rpc.channel, rpc.serverQueue)
    if err != nil {
        return
    }

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

    go func() {
        <-sigChan
        log.Printf("  [!] SIGTERM/SIGINT recieved, stopping new deliveries and processing remaining messages")
        // Lets clean things uuup, stop delivers to the consumer
        // i'm not sure if this blocks itself, or if we need to block
        // until len(msgs) == 0...
        rpc.channel.Cancel(rpc.serverQueue, false)
        log.Printf("  [!] Finished processing messages, exiting...")

        // close channel cleanly
        rpc.channel.Close()

        // success i guess?
        os.Exit(0)
    }()

    go func() {
        for msg := range msgs {
            // XXX-JWS: jws.Verify(body)
            cb, present := rpc.dispatchTable[msg.Type]
            log.Printf(" [s<] received %s(%s) [%s]", msg.Type, core.B64enc(msg.Body), msg.CorrelationId)
            if !present {
                continue
            }
            response := cb(msg.Body)
            log.Printf(" [s>] sending %s(%s) [%s]", msg.Type, core.B64enc(response), msg.CorrelationId)
            rpc.channel.Publish(
                AmqpExchange,
                msg.ReplyTo,
                AmqpMandatory,
                AmqpImmediate,
                amqp.Publishing{
                    CorrelationId: msg.CorrelationId,
                    Type:          msg.Type,
                    Body:          response, // XXX-JWS: jws.Sign(privKey, body)
                })
        }
    }()
    return
}