Saving a workflow via st2flow to a pack with no write permissions throws a 500

[lakshmi-kannan]

IOError: [Errno 13] Permission denied: u'/opt/stackstorm/packs/examples/actions/workflows/mistral-basic.yaml'
2017-02-15 14:04:39,657 81402288 INFO hooks [-] 6ef334bf-88f7-4ee0-9e3e-fbc5c3d7ec6f - PUT /v1/actions/58a45ec155fc8c0fbbf1e7eb result={
    "faultstring": "Internal Server Error"
} (result='{\n    "faultstring": "Internal Server Error"\n}',request_id='6ef334bf-88f7-4ee0-9e3e-fbc5c3d7ec6f',status_code='500 Internal Server Error',remote_addr='127.0.0.1',path='/v1/actions/58a45ec155fc8c0fbbf1e7eb',method='PUT')

Steps to repro

1. Install examples pack and register actions from it via st2ctl reload --register-all

2. Click EDIT and open a mistral workflow in FLOW

3. Click SAVE button

[LindsayHill]

What's your thoughts on how to handle this? Still raise a 500, but change the fault string to something like "Writing workflow to disk failed: Check permissions" ?

[xer0times]

Here's what I got when I saved a workflow:

Error saving workflow.: Unable to write data to "/opt/stackstorm/packs/default/actions/workflows/echo-test.yaml" (permission denied). Make sure permissions for that pack directory are configured correctly so st2api can write to it.

Is there a script or a hack to fix permissions on st2's directories?