element/start.go

package element

import (
	"fmt"
	"net"

	"github.com/sirupsen/logrus"
)

// Start activates the GRPC listener as well as joins the cluster if specified and blocks until a SIGTERM or SIGINT is received
func (a *Agent) Start() error {
	logrus.WithFields(logrus.Fields{
		"grpc":      fmt.Sprintf("%s:%d", a.config.AgentAddr, a.config.AgentPort),
		"bind":      fmt.Sprintf("%s:%d", a.config.BindAddr, a.config.BindPort),
		"advertise": fmt.Sprintf("%s:%d", a.config.AdvertiseAddr, a.config.AdvertisePort),
	}).Info("starting agent")
	l, err := net.Listen("tcp", fmt.Sprintf("%s:%d", a.config.AgentAddr, a.config.AgentPort))
	if err != nil {
		return err
	}
	go a.grpcServer.Serve(l)

	// start node metadata updater
	go func() {
		for {
			<-a.peerUpdateChan
			if err := a.members.UpdateNode(nodeUpdateTimeout); err != nil {
				logrus.Errorf("error updating node metadata: %s", err)
			}
		}
	}()

	if len(a.config.Peers) > 0 {
		logrus.Debugf("joining peers: %v", a.config.Peers)
		n, err := a.members.Join(a.config.Peers)
		if err != nil {
			return err
		}

		logrus.Infof("joined %d peer(s)", n)
	}

	return nil
}