// Leader returns the node of the current cluster leader. This returns an empty string if there is no leader.
func (c *Candidate) Leader() string {
consul := c.consulClient()
kv, _, err := consul.KV().Get(c.LeadershipKey, nil)
if kv == nil || err != nil {
logrus.Warnln("There is no leader.")
return ""
}
return string(kv.Value)
}
// RetrieveNode is a helper to retrieve the current node name of the agent.
func (c *Candidate) retrieveNode() {
consul := c.consulClient()
agent, err := consul.Agent().Self()
if err != nil {
logrus.Warnln("Unable to retrieve node name.")
return
}
c.node = agent["Config"]["NodeName"].(string)
}
// RetrieveSession retrieves the existing session needed to run leader election. If a session does not exist, a new
// session is created with the LeadershipKey as the name.
func (c *Candidate) retrieveSession() {
consul := c.consulClient()
if sessions, _, err := consul.Session().List(nil); err != nil {
logrus.Warnln("Unable to retrieve list of sessions.")
} else {
for _, session := range sessions {
if session.Name == c.LeadershipKey && session.Node == c.node {
c.session = session.ID
return
}
}
}
newSession := &consulapi.SessionEntry{
Name: c.LeadershipKey,
}
if sessionId, _, err := consul.Session().Create(newSession, nil); err != nil {
logrus.Errorln("Unable to create new sessions:", err)
} else {
c.session = sessionId
}
}