nova.cmd.baseproxy handles errors incorrectly

[Alexander Aleksiyants]

Nova from master.

The module doesn't print error message. If an error occurs in nova.cmd.baseproxy the method exit_with_error is executed that looks as follows:

def exit_with_error(msg, errno=-1):
    print(msg) and sys.exit(errno)

So in python 2.7 this method terminates the application without printing anything (unable to flush on time) and in python 3.4 it does strange things because print() returns None.

I noticed this bug when I was trying to run nova-novncproxy without novnc istalled. nova-novncproxy was being terminated without any prints. Then I debugged it and found out that it tries to send an error message but it fails.

[Markus Zoeller (markus_z) (mzoeller)]

Confirmed with this simple test with python2.7:

    import sys

    def exit_with_error(msg, errno=-1):
        print(msg) and sys.exit(errno)

    if __name__ == "__main__":
        exit_with_error("print this message")

The message doesn't get flushed.

[Markus Zoeller (markus_z) (mzoeller)]

@Wen Zhi Yu: Thanks for taking over the task to provide a fix for this bug. Please push a patch set within the next few weeks.

A short reminder on the bug mgmt process: If you set yourself as assignee, please change the status of the bug to "in progress".

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/237886

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/237886
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=cf7cd655a2aaa7f44b94dca0ad7a15073a774a48
Submitter: Jenkins
Branch: master

commit cf7cd655a2aaa7f44b94dca0ad7a15073a774a48
Author: Wen Zhi Yu <email address hidden>
Date: Wed Oct 21 13:38:22 2015 +0800

    Fix error handling in nova.cmd.baseproxy

    If an error occurs in nova.cmd.baseproxy the method exit_with_error
    will be executed that looks as follows:

    def exit_with_error(msg, errno=-1):
     print(msg) and sys.exit(errno)

    However, in python2.7 this method terminates the application without
    printing anything(unable to flush on time) and in Python3.4 it does
    strange things because print() returns None.

    This commit modifies exit_with_error method to output error message
    with stderr(which in unbuffered).

    Change-Id: I519b68f8c2bc62988de87bdd2847d5f3be7e532d
    Closes-Bug: #1506213

[Markus Zoeller (markus_z) (mzoeller)]

We changed the release management from a "delayed-release" to a
"direct-release" model [1]. It seems that the fix for this bug merged
in the timeframe where we made the transition to the new model and
therefore wasn't closed with "Fix-Released" at it should be.
=> Manually closing this bug with "Fix-Released".

[1] "openstack-dev" ML, 2015-11-23, Doug Hellmann,
    "[release] process change for closing bugs when patches merge"
    http://lists.openstack.org/pipermail/openstack-dev/2015-November/080288.html

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/nova 13.0.0.0b2 development milestone.