> On 19 Oct 2015, at 07:53, WANG, Ming Hao (Tony T)
> <tony.a.w...@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 [1] 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.
Thanks
[1] https://blueprints.launchpad.net/mistral/+spec/action-providers
<https://blueprints.launchpad.net/mistral/+spec/action-providers>
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