[Freeipa-devel] [PATCH] 324 Add fallback for httpd restarts

[Martin Kosek]

On 10/18/2012 04:36 PM, Rob Crittenden wrote:
> Martin Kosek wrote:
>> On 10/18/2012 02:47 PM, Rob Crittenden wrote:
>>> Martin Kosek wrote:
>>>> Attaching a script I used to reproduce the issue on machine with sysV (RHEL
>>>> 6.4
>>>> in my case). With the patch applied, httpd restarts correctly fallback-ed.
>>>>
>>>> If you think that the wait is not enough, I can add a more complicated
>>>> procedure, like this one:
>>>>
>>>> wait_time = 5
>>>> retries = 3
>>>>
>>>> for x in xrange(retries):
>>>>       try:
>>>>          sleep(wait_time)
>>>>          http.stop()
>>>>          sleep(wait_time)
>>>>          http.start()
>>>>       except CalledProcessError:
>>>>          wait_time = wait_time * 2
>>>>          continue
>>>>       break
>>>>
>>>>
>>>> ----
>>>>
>>>> httpd init script on sysV based platforms cannot guarantee that two
>>>> consecutive httpd service restarts succeed when run in a small
>>>> time distance.
>>>>
>>>> Add fallback procedure that adds additional waiting time after such
>>>> failed restart attempt, and then try to stop and start the service
>>>> again.
>>>>
>>>> https://fedorahosted.org/freeipa/ticket/2965
>>>
>>>
>>> Should we attempt to retrieve a file to ensure that the service is up? The
>>> ipa.crt would be a candidate for this.
>>>
>>> rob
>>
>> Hm, this looks over-engineered from my POV. We already check that ports are
>> open, right?
> 
> Well, this is assuming that sysV is going to return an error when httpd doesn't
> start. It should at least call service status to make sure the service is
> operational.
> 
> rob
> 

Actually, we generally already do that as a part of start() process, you will
see it when running my test script:

DEBUG: stderr=
DEBUG: args=/sbin/service httpd restart
DEBUG: stdout=Stopping httpd:                              [FAILED]
Starting httpd:                                            [FAILED]

DEBUG: stderr=(98)Address already in use: make_sock: could not bind to address
[::]:80
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs

DEBUG: httpd restart failed, try to stop&start again
DEBUG: args=/sbin/service httpd stop
DEBUG: stdout=Stopping httpd:                              [  OK  ]

DEBUG: stderr=
DEBUG: args=/sbin/service httpd start
DEBUG: stdout=Starting httpd:                              [  OK  ]

DEBUG: stderr=
DEBUG: args=/sbin/service httpd status          <<<<<<<<<<
DEBUG: stdout=httpd dead but subsys locked

But I just realized, that my change in httpinstance.py is redundant, it uses
platform service to do the restart which has the fallback already, i.e.
modification there is enough. Updated patch attached.

Martin
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