[vdsm] Smarter network_setup hooks

[Livnat Peer]

On 01/05/2014 12:05 PM, Assaf Muller wrote:
> Whichever way we decide to do this, I think the important bit is documentation - We have
> to make sure to update the oVirt wiki hooks pages. If users aren't aware of how to retrieve
> the networking config then we might as well not implement it.
> 
> That being said, I'd expose three dictionaries: What's currently configure,
> the current request, as well as the proposed end result. It's easy to add
> and I see how it would be useful to hook writers. And just to state the obvious,
> just like how traditional hooks can change the VM or device XML,
> the hook should be able to rewrite the current request contents.
> For example, if a user would like to take over host networking configuration,
> he could just write a before_setup_networks hook that would configure
> networking however he wants, then writes the empty dictionary to the current request,
> meaning that VDSM wouldn't do anything further with the current setup networks request.
> 

+1,
I think the API above would be easy to consume.

Livnat


> 
> Assaf Muller, Cloud Networking Engineer 
> Red Hat 
> 
> ----- Original Message -----
> From: "Miguel Angel" <miguelangel at ajo.es>
> To: "Adam Litke" <alitke at redhat.com>
> Cc: dsulliva at redhat.com, arch at ovirt.org, vdsm-devel at fedorahosted.org
> Sent: Saturday, January 4, 2014 9:08:17 PM
> Subject: Re: [vdsm] Smarter network_setup hooks
> 
> Hi Adam 
> 
> Thanks for the feedback 
> 
> 2014/1/3 Adam Litke < alitke at redhat.com > 
> 
> 
> 
> On 03/01/14 12:20 +0000, Dan Kenigsberg wrote: 
> 
> 
> Recently, Miguel Angel Ajo (CCed) has added a nice functionality to the 
> implementation of setupNetworks in Vdsm: two hook points where added: 
> before and after the setupNetworks verb takes place. 
> [....] 
> Seems like a logical thing to do. What specific mechanism do you 
> suggest for passing the JSON strings to the hook script? If passed as 
> arguments to the hook script we would need to consider shell escaping 
> and argv length restrictions. 
> 
> As for the libvirt domain xml we pass to other hooks, we write a temporary file 
> and we set an environment variable pointing to it before calling the script 
> 
> 
> What about writing these out to a special file and adding a new 
> getContext() call to the hooking module. A script that is unconcerned 
> with the context would not require any changes. But a script that 
> wants access would simply do: 
> 
> ctx = hooking.getContext() 
> 
> and ctx would be the contents of the special file already decoded into 
> a native Python object for easy consumption. This could easily be 
> extended to any hook which may want to provide some context to 
> implementors. 
> 
> That would be nice, so scripts written in python wouldn't need to look for, and parse 
> the file. 
> 
> This is an example of a simple hook: 
> 
> http://gerrit.ovirt.org/#/c/20330/7/tests/functional/networkTests.py (look inside the ValidatesHook decorator) 
> 
> It'd be quite simplified. We would also need a "setContext()..." to update context with changes. 
> 
> 
> 
> One more question comes to mind: Are there any pieces of information 
> that we would need to redact from the context (passwords or other 
> sensitive information)? 
> 
> 
> I think there is no sensitive information as far as I know. 
> 
> Greetings, 
> Miguel Ángel. 
> 
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