YAQL raises error if it gets '{some text}' as expression

[Nikolay Makhotkin]

Steps to reproduce:

1. Create workflow and provide input to task something like '{assd}':

---
version: "2.0"
wf22:
  type: direct
  tasks:
    task1:
      action: std.echo output="{some text}"

2. Type mistral execution-create wf22

3. Get YaqlGrammarError or YaqlLexicalException:

http://paste.openstack.org/show/163632/
or
http://paste.openstack.org/show/163630/

Suggested solution: We should return the same string we get in YAQLEvaluator.

[Dmitri Zimine (i-dz)]

hm...
but what if the string is fat-fingered yaql expression? what indicates that it is a string?

[Dmitri Zimine (i-dz)]

After thinking about it more:

{'this should work'} but {this should fail}.

1) in the first case, user wants to pass a string and explicitly stating that it's a string. It's a question why anyone would do so, but
2) in the second case, how system tells apart an intention to pass a string from fat-fingered yaql? {lenght(4)} is this a string or a mistyped function call? The YAQL exception in place is a better behavior than resolving it to the string to fail few steps down.

at the risk of restating the obvious: Fail Fast

* http://www.practical-programming.org/articles/fail_fast_principle/fail_fast_principle.html
* http://www.martinfowler.com/ieeeSoftware/failFast.pdf

[Renat Akhmerov (rakhmerov)]

 hm.., yes, 1) doesn't make any sense but you're right it's up to them. We just need to have clear simple rules about this.

As far as 2) I think we should just raise an exception. Agree on 'fail-fast'.

So overall, 1) rule seems to be enough.

[Renat Akhmerov (rakhmerov)]

So I think this behavior is not a but and propse to close it.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/151975
Committed: https://git.openstack.org/cgit/stackforge/mistral/commit/?id=6a2481c6c6de0274d8784477b6719f4d05054ab0
Submitter: Jenkins
Branch: master

commit 6a2481c6c6de0274d8784477b6719f4d05054ab0
Author: Dmitri Zimine <email address hidden>
Date: Sun Feb 1 16:12:47 2015 -0800

    Catch workflow errors

    Avoid keeping workflow in zombie state: on unexpected errors
    fail the workflow execution and save error information. If possible,
    fail the correspondent tasks, too.

    Done:
    - [x] Introduce state_info into Execution, fill it with error info
    when workflow fails.
    - [x] Add error handlers to `on_task_result` and `run_task`
    - [x] Add error handlers and tests to `start_workflow`
    - [x] Add tests for YAQL eval exceptions
    - [x] Add error handler and tests to `resume_worklfow`

    TODO:
    - [ ] Make _fail_workflow public and let user fail workflow via API
    (on separate commit)

    Closes-bug: 1415886
    Change-Id: Ib1fd661580d3a426dbbc7401a3622a98c7840e00