Neutron daemon Pidfile class does not need to not use root_helper

[Brian Haley]

I noticed while writing a daemon that used the daemon Pidfile class that it defaults to using sudo, so not passing rootwrap will generate errors like this:

2013-07-19 17:53:44.512 3111 DEBUG quantum.agent.linux.utils [-] Running command: ['sudo', 'cat', '/proc/23384/cmdline'] execute /usr/lib/python2.7/dist-packages/quantum/agent/linux/utils.py:42
2013-07-19 17:53:44.533 3111 DEBUG quantum.agent.linux.utils [-]
Command: ['sudo', 'cat', '/proc/23384/cmdline']
Exit code: 1
Stdout: ''
Stderr: 'sudo: no tty present and no askpass program specified\nSorry, try again.\nsudo: no tty present and no askpass program specified\nSorry, try again.\nsudo: no tty present and no askpass program specified\nSorry, try again.\nsudo: 3 incorrect password attempts\n' execute /usr/lib/python2.7/dist-packages/quantum/agent/linux/utils.py:59

We actually don't need root priveleges to read /proc/$pid/cmdline, so root_helper can be removed along with the rootwrap filters for it.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/44198

[Armando Migliaccio (armando-migliaccio)]

If I understand this correctly you get the error because you don't have a nopasswd sudo user, so you'd get the same error with the rootwrapper if it wasn't configured correctly (i.e. you don't have the file /etc/sudoers.d/neutron-rootwrap).

[Brian Haley (brian-haley)]

Right, I saw the error because I didn't have a nopasswd sudo user creating a daemon.

I found this because I used the metadata-proxy code as a starting point for something else, and it has this code:

class ProxyDaemon(daemon.Daemon):
    def __init__(self, pidfile, port, network_id=None, router_id=None):
        uuid = network_id or router_id
        super(ProxyDaemon, self).__init__(pidfile, uuid=uuid)
        self.network_id = network_id
        self.router_id = router_id
        self.port = port

That super() call actually should have a root_helper= in it, since otherwise when the Daemon class initializes self.pidfile, it will try and use sudo.

I felt removing the use of sudo/root_helper altogther was a better fix since it wasn't needed.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/44198
Committed: http://github.com/openstack/neutron/commit/89e38929d2bc626b639df9912a98d24b25a7e964
Submitter: Jenkins
Branch: master

commit 89e38929d2bc626b639df9912a98d24b25a7e964
Author: Brian Haley <email address hidden>
Date: Tue Aug 27 17:36:43 2013 -0400

    Change daemon Pidfile class to not use root_helper

    Some users of the Pidfile class don't specify root_helper,
    which then defaults to 'sudo', which will generate an error.
    Remove root_helper altogether since we actually don't need
    root priveleges to read /proc/$pid/cmdline.

    Changed code to use open.readline() instead of a shell, and
    tweaked tests accordingly.

    Also cleaned-up the rootwrap filters that allow it as they
    are not used anymore.

    Fixes bug 1218142

    Change-Id: I6691feb1c9f7bfa261a7ec464fd8f3f92168c302