[openstack-dev] [mistral] How to call 3rd-party tools(such as Ansible) in Mistral
WANG, Ming Hao (Tony T)
tony.a.wang at alcatel-lucent.com
Mon Oct 19 07:18:06 UTC 2015
Thanks for your info.
I like your option2(https://blueprints.launchpad.net/mistral/+spec/action-providers). ☺
Any schedule for this? Looks like it isn’t started yet.
From: Renat Akhmerov [mailto:rakhmerov at mirantis.com]
Sent: Monday, October 19, 2015 2:58 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [mistral] How to call 3rd-party tools(such as Ansible) in Mistral
On 19 Oct 2015, at 07:53, WANG, Ming Hao (Tony T) <tony.a.wang at alcatel-lucent.com<mailto:tony.a.wang at alcatel-lucent.com>> wrote:
The “custom action” needs to re-install Mistral.
If the Mistral service is part of 3rd party OpenStack, it may be unacceptable to let every user create his own customer action. What do you think?
Yes, correct. It requires reinstall. If your goal is to give users possibility to create custom actions "on the fly” then it’s now impossible in Mistral for fundamental reasons. We can’t let users upload arbitrary Python code via API for security reasons. However, we have a couple of ideas that we’re going to explore in order to partially close this gap:
* Keep action code on a client-side, sort of what StackStorm does. But IMO we could think about automating it in a more elegant and transparent way. For example, we could use decorators in python code that would associate a function or a class with a certain workflow task. Then a workflow could call this code back while its running using some mechanism (i.e. some special action). In this case, however, we’d have to have a process handling callback requests from Mistral on a client side. The alternative: using HTTP Long Poll mechanism so that a client could claim available tasks itself.
* We have BP  that describes the idea of using so-called action providers. It assumes that we can register trustworthy action providers that could dynamically provide new actions to Mistral. I personally like this idea and to some extent it would solve this issue but it requires some additional setup which works for cases like StackStorm but doesn’t work if we want to use Mistral as is, as a hosted workflow service.
Anyway, whatever solution we accept it will be a trade-off and depend on a particular use case.
Ad-hoc actions may also work for you if, for example, we create enough base actions that they could be built upon. Say if most of your actions are HTTP based then you can just create your own library (e.g. a workbook) of ad-hoc actions that will be wrappers around std.http.
Also look at what StackStorm does, it may also be helpful.
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