salt module with a decorator

[Emile `iMil' Heitor]

Hi,

I am finalizing a module which needs, for pretty much every function,
to create a session, and logout that session when the job is done.
To achieve this, I used a simple decorator:

def _session_handle(function):
def _internal(*args, **kwargs):
_session = _get_session()
ret = function(_session.xenapi, *args, **kwargs)
_session.logout()
return ret
return _internal

Which is referred to like this:

@_session_handle
def vm_info(xapi, vm_=None):

While the module behaves correctly when it is called from `salt-call', it
fails with the following error when it's called from plain `salt':

$ sudo salt 'coruscant' virt.vm_info
coruscant:
Missing arguments executing "virt.vm_info": ArgSpec(args=[], varargs='args', keywords='kwargs', defaults=None)

First I thought it was related to the fact that the decorator added a session
parameter to the functions, so I made the session variable global, so the
decorator now looks like this:

def _session_handle(function):
def _internal(*args, **kwargs):
global xapi
_session = _get_session()
xapi = _session.xenapi
ret = function(*args, **kwargs)
_session.logout()
return ret
return _internal

Nevertheless, I am still stuck with the same "Missing argument" error.
Is there any known issue when using a decorator within modules? I can't
actually find one that uses it except for @salt.utils.memoize.

Thanks for any pointer.

Cheers,

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[Colton Myers]

Do you have a link to your in-progress module?  I'd be interested to see where/how the decorator is defined.

(Really I have no idea why it would work on salt-call and not on salt, so I'm just looking for more information.)

--

Colton Myers

Emile `iMil' Heitor .°. <imil@{home.imil.net,NetBSD.org,gcu.info}>

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[Emile `iMil' Heitor]

> Do you have a link to your in-progress module? �I'd be interested to see
> where/how the decorator is defined.

Of course, you'll find it there http://imil.net/stuff/xapi.py

Thanks

[Emile `iMil' Heitor]

On Mon, 20 May 2013, Emile `iMil' Heitor wrote:

> Nevertheless, I am still stuck with the same "Missing argument" error.
> Is there any known issue when using a decorator within modules? I can't
> actually find one that uses it except for @salt.utils.memoize.

FWIW, using context manager instead of a decorator seem to work.

------------------------------------------------------------------
Emile `iMil' Heitor .�. <imil@{home.imil.net,NetBSD.org,gcu.info}>

[Colton Myers]

Very strange.  Let me ask those who know the import and loader systems in salt better than I, and get back to you.  I myself can't imagine what's different between running on salt-call vs salt.

--

Colton Myers

[Thomas S Hatch]

This error is thrown when there is a TypeError thrown by the calling of the function. The functions are all loaded and called in the same way via salt and salt-call though...

Thomas S. Hatch  |  Founder, CTO

5272 South College Drive, Suite 301 | Murray, UT 84123

tha...@saltstack.com | www.saltstack.com

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[Emile `iMil' Heitor]

Hi Thomas,

> This error is thrown when there is a TypeError thrown by the calling of the
> function. The functions are all loaded and called in the same way via salt
> and salt-call though...

Well, as you may have seen, I've moved from decorator to context manager
which makes the overall session handling code cleaner anyway.
Side note, the @contextmanager decorator is exposed as an available
function with sys.doc:

$ sudo salt 'coruscant' sys.doc virt|grep contextmanager
virt.contextmanager:
@contextmanager decorator.
@contextmanager

Is there a way to avoid that?

[Thomas S Hatch]

Ahh, yes, it should not be imported as a function, lemme look

Thomas S. Hatch  |  Founder, CTO

5272 South College Drive, Suite 301 | Murray, UT 84123

tha...@saltstack.com | www.saltstack.com

[Thomas S Hatch]

https://github.com/saltstack/salt/commit/1e50ec05376a88f9d8d0e7c84c9ea4542fed1846

Thomas S. Hatch  |  Founder, CTO

5272 South College Drive, Suite 301 | Murray, UT 84123

tha...@saltstack.com | www.saltstack.com

[Emile `iMil' Heitor]

> https://github.com/saltstack/salt/commit/1e50ec05376a88f9d8d0e7c84c9ea4542f
> ed1846

Thanks :)

Just curious, what's the rule and/or where can I find it?

[Antoine Pitrou]

Le Mon, 20 May 2013 23:29:14 +0200 (CEST),
Emile `iMil' Heitor <im...@NetBSD.org> a
écrit :

>
> Hi,
>
> I am finalizing a module which needs, for pretty much every function,
> to create a session, and logout that session when the job is done.
> To achieve this, I used a simple decorator:
>
> def _session_handle(function):
> def _internal(*args, **kwargs):
> _session = _get_session()
> ret = function(_session.xenapi, *args, **kwargs)
> _session.logout()
> return ret
> return _internal

For the record, you could use a try..finally here, so as to logout even
if your function() raises an exception.

Regards

Antoine.

[Thomas S Hatch]

The rule? Or the quiet option? The rule is to just never import salt.modules.anything

Thomas S. Hatch  |  Founder, CTO

5272 South College Drive, Suite 301 | Murray, UT 84123

tha...@saltstack.com | www.saltstack.com