[Freeipa-devel] [PATCH 0208] Respect --test option in upgrade plugins

[Jan Cholasta]

Dne 13.3.2015 v 11:17 Martin Kosek napsal(a):
> On 03/13/2015 11:00 AM, Petr Spacek wrote:
>> On 13.3.2015 10:42, Alexander Bokovoy wrote:
>>> On Fri, 13 Mar 2015, Petr Spacek wrote:
>>>> On 13.3.2015 10:18, Martin Kosek wrote:
>>>>> On 03/12/2015 05:10 PM, Rob Crittenden wrote:
>>>>>> Petr Spacek wrote:
>>>>>>> On 12.3.2015 16:23, Rob Crittenden wrote:
>>>>>>>> David Kupka wrote:
>>>>>>>>> On 03/06/2015 06:00 PM, Martin Basti wrote:
>>>>>>>>>> Upgrade plugins which modify LDAP data directly should not be
>>>>>>>>>> executed
>>>>>>>>>> in --test mode.
>>>>>>>>>>
>>>>>>>>>> This patch is a workaround, to ensure update with --test
>>>>>>>>>> option will not
>>>>>>>>>> modify any LDAP data.
>>>>>>>>>>
>>>>>>>>>> https://fedorahosted.org/freeipa/ticket/3448
>>>>>>>>>>
>>>>>>>>>> Patch attached.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Ideally we want to fix all plugins to dry-run the upgrade not
>>>>>>>>> just skip
>>>>>>>>> when there is '--test' option but it is a good first step.
>>>>>>>>> Works for me, ACK.
>>>>>>>>>
>>>>>>>>
>>>>>>>> I agree that this breaks the spirit of --test and think it
>>>>>>>> should be
>>>>>>>> fixed before committing.
>>>>>>>
>>>>>>> Considering how often is the option is used ... I do not think
>>>>>>> that this
>>>>>>> requires 'proper' fix now. It was broken for *years* so this
>>>>>>> patch is a huge
>>>>>>> improvement and IMHO should be commited in current form. We can
>>>>>>> re-visit it
>>>>>>> later on, open a ticket :-)
>>>>>>>
>>>>>>
>>>>>> No. There is no rush for this, at least not for the promise of a
>>>>>> future
>>>>>> fix that will never come.
>>>>>
>>>>> I checked the code and to me, the proper fix looks like instrumenting
>>>>> ldap.update_entry calls in upgrade plugins with
>>>>>
>>>>> if options.test:
>>>>>     log message
>>>>> else
>>>>>     do the update
>>>>>
>>>>> right? I see just couple places that would need to be updated:
>>>>>
>>>>> $ git grep -E "(ldap|conn).update_entry" ipaserver/install/plugins
>>>>> ipaserver/install/plugins/dns.py:
>>>>> ldap.update_entry(container_entry)
>>>>> ipaserver/install/plugins/fix_replica_agreements.py:
>>>>> repl.conn.update_entry(replica)
>>>>> ipaserver/install/plugins/fix_replica_agreements.py:
>>>>> repl.conn.update_entry(replica)
>>>>> ipaserver/install/plugins/update_idranges.py: ldap.update_entry(entry)
>>>>> ipaserver/install/plugins/update_idranges.py: ldap.update_entry(entry)
>>>>> ipaserver/install/plugins/update_managed_permissions.py:
>>>>> ldap.update_entry(base_entry)
>>>>> ipaserver/install/plugins/update_managed_permissions.py:
>>>>> ldap.update_entry(entry)
>>>>> ipaserver/install/plugins/update_pacs.py:
>>>>> ldap.update_entry(entry)
>>>>> ipaserver/install/plugins/update_referint.py:
>>>>> ldap.update_entry(entry)
>>>>> ipaserver/install/plugins/update_services.py: ldap.update_entry(entry)
>>>>> ipaserver/install/plugins/update_uniqueness.py:
>>>>> ldap.update_entry(uid_uniqueness_plugin)
>>>>>
>>>>>
>>>>> So from my POV, very quick fix. In that case, I would also prefer a
>>>>> fix now
>>>>> than a ticket that would never be done.
>>>>
>>>> I really dislike this approach because I consider it flawed by
>>>> design. Plugin
>>>> author has to think about it all the time and do not forget to add if
>>>> otherwise ... too bad.
>>>>
>>>> I can see two 'safer' ways to do that:
>>>> - LDAP transactions :-)
>>>> - 'mock_writes=True' option in LDAP backend which would print
>>>> modlists instead
>>>> of applying them (and return success to the caller).
>>>>
>>>> Both cases eliminate the need to scatter 'ifs' all over update
>>>> plugins and do
>>>> not add risk of forgetting about one of them when adding/changing
>>>> plugin code.
>>> I like idea about mock_writes=True. However, I think we still need to
>>> make
>>> sure plugin writers rely on options.test value to see that we aren't
>>> going to write the data. The reason for it is that we might get into
>>> configurations where plugins would be doing updates based on earlier
>>> performed tasks.  If task configuration is not going to be written, its
>>> status will never be correct and plugin would get an error.
>>
>> That is exactly why I mentioned LDAP transactions. There is no other
>> way how
>> to test complex plugins which actually read own writes (except mocking
>> the
>> whole LDAP interface somewhere).
>
> While this may be a good idea long term, I do not think any of us is
> considering implementing the LDAP transaction support within work on
> this refactoring.
>
> So in this thread, let us focus on how to fix options.test mid-term. I
> currently see 2 proposed ways:
> - Making the plugins aware of options.test
> - Make ldap2 write operations only print the update and not do it.
> Although thinking of this approach, I think it may make some plugins
> like DNS loop forever. IIRC, at least DNS upgrade plugin have loop
>    - search for all unfixed DNS zones
>    - fix them with ldap update
>    - was the search truncated, i.e.  are there more zones to update?
>      if yes, go back to start

  - Make the plugins not call {add,update,delete}_entry themselves but 
rather return the updates like they should. This is what the ticket 
(<https://fedorahosted.org/freeipa/ticket/3448>) requests and what 
should be done to make --test work for them.

-- 
Jan Cholasta