// ConsulSessionManager continually creates and maintains Consul sessions. It is intended
// to be run in its own goroutine. If one session expires, a new one will be created. As
// sessions come and go, the session ID (or "" for an expired session) will be sent on the
// output channel.
//
// Parameters:
// config: Configuration passed to Consul when creating a new session.
// client: The Consul client to use.
// output: The channel used for exposing Consul session IDs. This method takes
// ownership of this channel and will close it once no new IDs will be created.
// done: Close this channel to close the current session (if any) and stop creating
// new sessions.
// logger: Errors will be logged to this logger.
func ConsulSessionManager(
config api.SessionEntry,
client *api.Client,
output chan<- string,
done chan struct{},
logger logging.Logger,
) {
logger.NoFields().Info("session manager: starting up")
for {
// Check for exit signal
select {
case <-done:
logger.NoFields().Info("session manager: shutting down")
close(output)
return
default:
}
// Establish a new session
id, _, err := client.Session().CreateNoChecks(&config, nil)
if err != nil {
logger.WithError(err).Error("session manager: error creating Consul session")
time.Sleep(SessionRetryTimeout)
continue
}
sessionLogger := logger.SubLogger(logrus.Fields{
"session": id,
})
sessionLogger.NoFields().Info("session manager: new Consul session")
select {
case output <- id:
// Maintain the session
err = client.Session().RenewPeriodic(config.TTL, id, nil, done)
if err != nil {
sessionLogger.WithError(err).Error("session manager: lost session")
} else {
sessionLogger.NoFields().Info("session manager: released session")
}
output <- ""
case <-done:
// Don't bother reporting the new session if exiting
client.Session().Destroy(id, nil)
sessionLogger.NoFields().Info("session manager: released session")
}
}
}
