yahoo-eng-team team mailing list archive

[Bert JW Regeer <1620845@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

When using systemd on CentOS 7/RHEL 7 with cloud-init configured to use
ConfigDrive on OpenStack, cloud-init-local needs to have a line added to
it's unit file that makes sure it gets to finish before NetworkManager
is started.

Before=NetworkManager.service

NetworkManager wants target network.target, currently that means it runs
at the same time as cloud-init-local, which means it will start DHCP and
write /etc/resolv.conf while cloud-init-local is parsing the ConfigDrive
and is writing the appropriate ifcfg-* files.

This causes a race condition with who gets to modify /etc/resolv.conf.
NetworkManager does not take kindly to that race.

When NetworkManager notices the new ifcfg-* files it will turn off DHCP
and mark the interfaces "unmanaged", however it doesn't notice the
change made to /etc/resolv.conf.

Related to the changes made here:

https://code.launchpad.net/~bregeer-ctl/cloud-init/+git/cloud-
init/+merge/305058

If NetworkManager is started after cloud-init-local, then NetworkManager
will correctly see that  /etc/resolv.conf is not to be touched by it.

** Affects: cloud-init
     Importance: Undecided
         Status: New


** Tags: centos rhel

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https://bugs.launchpad.net/bugs/1620845

Title:
  cloud-init-local.service should add Before=NetworkManager

Status in cloud-init:
  New

Bug description:
  When using systemd on CentOS 7/RHEL 7 with cloud-init configured to
  use ConfigDrive on OpenStack, cloud-init-local needs to have a line
  added to it's unit file that makes sure it gets to finish before
  NetworkManager is started.

  Before=NetworkManager.service

  NetworkManager wants target network.target, currently that means it
  runs at the same time as cloud-init-local, which means it will start
  DHCP and write /etc/resolv.conf while cloud-init-local is parsing the
  ConfigDrive and is writing the appropriate ifcfg-* files.

  This causes a race condition with who gets to modify /etc/resolv.conf.
  NetworkManager does not take kindly to that race.

  When NetworkManager notices the new ifcfg-* files it will turn off
  DHCP and mark the interfaces "unmanaged", however it doesn't notice
  the change made to /etc/resolv.conf.

  Related to the changes made here:

  https://code.launchpad.net/~bregeer-ctl/cloud-init/+git/cloud-
  init/+merge/305058

  If NetworkManager is started after cloud-init-local, then
  NetworkManager will correctly see that  /etc/resolv.conf is not to be
  touched by it.

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