When the Job Tracker goes down, Hue cannot display the Jobs in File Browser or submit to the correct cluster.
In MR1, Hadoop can support two Job Trackers, a master Job Tracker that can fail over to a standby Job Tracker and hence provide Job Tracker HA. Let’s see how Hue 3.5 and CDH5beta1 (and probably CDH4.6) can take advantage of this.
We configure two Job Trackers in the hue.ini:
[hadoop] ... [[mapred_clusters]] [[[default]]] # Enter the host on which you are running the Hadoop JobTracker jobtracker_host=host-1 # Whether to submit jobs to this cluster submit_to=True [[[ha-standby]]] # Enter the host on which you are running the Hadoop JobTracker jobtracker_host=host-2 # Whether to submit jobs to this cluster submit_to=True
And that’s it! Hue will communicate with the available Job Tracker automatically!
Notice that in the case of Oozie jobs, Oozie will try to re-submit the job but will need a logical name (HUE-1631). To enable this in Hue, specify it in each MapReduce cluster, e.g.:
[hadoop] [[mapred_clusters]] [[[default]]] # JobTracker logical name. ## logical_name=MY_NAME