timetable-mgr/src/messaging/client.go

package messaging

import (
	"os"

	"git.fjla.uk/owlboard/mq-client/log"
	"go.uber.org/zap"

	"github.com/go-stomp/stomp/v3"
)

type nrodCredential struct {
	user string
	pass string
}

// Fetches credentials from environment variables and exits if none provided.
func getCredentials() nrodCredential {
	var nrod_user string = os.Getenv("OWL_LDB_CORPUSUSER")
	var nrod_pass string = os.Getenv("OWL_LDB_CORPUSPASS")
	if nrod_user == "" || nrod_pass == "" {
		log.Msg.Fatal("No NROD Credentials provided")
	}
	log.Msg.Debug("NROD Credentials loaded for user: " + nrod_user)
	return nrodCredential{
		user: nrod_user,
		pass: nrod_pass,
	}
}

var Client = dial()

// Connects the STOMP file to the Network Rail MQ Server
func dial() *stomp.Conn {
	var credentials nrodCredential = getCredentials()
	conn, err := stomp.Dial("tcp", "publicdatafeeds.networkrail.co.uk:61618",
		stomp.ConnOpt.Login(credentials.user, credentials.pass),
		stomp.ConnOpt.HeartBeat(15000, 15000),
		stomp.ConnOpt.Header("client-id", credentials.user+"-mq-client"),
	)
	if err != nil {
		log.Msg.Fatal("Unable to connect to STOMP Client", zap.String("err", err.Error()))
		conn.MustDisconnect()
	}

	log.Msg.Info("Initialised STOMP Client")
	return conn
}

// Handles graceful disconnection of the STOMP client, falls back to
// a force disconnect if this fails.
func Disconnect(conn *stomp.Conn) {
	if conn != nil {
		err := conn.Disconnect()
		log.Msg.Warn("Disconnected STOMP Client")
		if err != nil {
			conn.MustDisconnect()
			log.Msg.Error("STOMP Disconnection failed, forced disconnect")
		}
		return
	}
	log.Msg.Error("STOMP Disconnect failed, next connection attempt may fail")
}

// Register against the MQ Server and log each message for testing purposes