[jira] [Created] (AMBARI-14842) ambari agent upstart support

["Andrew Onischuk (JIRA)" <ji...@apache.org>]

Andrew Onischuk created AMBARI-14842:
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             Summary: ambari agent upstart support
                 Key: AMBARI-14842
                 URL: https://issues.apache.org/jira/browse/AMBARI-14842
             Project: Ambari
          Issue Type: Bug
            Reporter: Andrew Onischuk
            Assignee: Andrew Onischuk
             Fix For: 2.4.0
         Attachments: AMBARI-14842.patch

Context:  
It is critical that we have a service that can auto-restart during crashes and
reboots. This is done via upstart on Ubuntu.  
The issue is that Ambari-Agent scripts in the current state is not upstart-
able due to some implementation issues.  
So to make this upstart-able, we had to directly take a dependency into a
helper script for Ambari-Agent (as per user1 recommendation). However, this
dependency turned out to be fragile, since it broke in HDP 2.4. So this JIRA
is about making ambari agent upstartable directly when we install Ambari, so
users doesn’t have to resort to a fragile dependency. We made it work  
Details:  
The way to start ambari-agent and ambari-server are different for user1 and
user2.  
In the case for ambari-agent:  
user1 calls "/etc/init.d/ambari-agent" (which invokes /usr/sbin/ambari-agent)
to start ambari agent.  
user2 uses "/etc/init/ambari-agent" (which directly calls /usr/lib/python2.6
/site-packages/ambari_agent/main.py) to start ambari-agent.  
user2 has to call ambari-agent/main.py directly is because we need upstart to
re-start services when it crashes unexpectedly and upstart does not work if we
configure it to call /usr/sbin/ambari-agent.  
The reason is that upstart needs to track the process for the service (i.e.
ambari-agent) that it needs to restart; however, /usr/sbin/ambari-agent
executes lots of commands that would result in new processes being spawned and
will confuse upstart the "main" process it should be tracking.  
We need user1 to give us a upstart-compatible script otherwise HDP changes can
break us unexpectedly.  
We also have a upstart script for ambari-server for the same reason.  
Attaching both scripts for user1 to take a look.





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