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Message #69793
[Bug 1717707] Re: EVENTLET_NO_GREENDNS is disabled in eventlet 0.20.*, The install guide should notice that nameserver needs to be configured on all nodes for name resolution
[Expired for openstack-manuals because there has been no activity for 60
days.]
** Changed in: openstack-manuals
Status: Incomplete => Expired
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https://bugs.launchpad.net/bugs/1717707
Title:
EVENTLET_NO_GREENDNS is disabled in eventlet 0.20.*, The install guide
should notice that nameserver needs to be configured on all nodes for
name resolution
Status in OpenStack Compute (nova):
Invalid
Status in openstack-manuals:
Expired
Bug description:
Related to bug #1696094.
An 'Timed out waiting for nova-conductor. Is it running? Or did this
service start before nova-conductor? Reattempting establishment of
nova-conductor connection...' error occurs in nova-compute.log if we
just follow the install guide, The situation is as below:
on compute node
1. no usable nameserver in /etc/resolv.conf
2. only ipv4 of 'controller' (as rabbitmq server) is mapped in /etc/hosts
3. use 'controller' as rabbitmq server in nova.conf
==========================================================================
The eventlet greendns has been always enabled by monkey_patch since
0.20.0, and this will introduce some compatibility problems, e.g.
1. We create a connection to rabbitmq server using 'controller:5672'
2. patched socket.getaddrinfo('controller', 5672, 0) is called by amqp (0 for both ipv4 and ipv6)
3. greendns will use '127.0.0.1' as dns nameserver if there is no usable nameserver in /etc/resolv.conf
4. greendns will perform name resolving for 'controller', ipv6 dns lookup will be performed if there is no ipv6 mapping for 'controller' in /etc/hosts, so is ipv4. One of the dns lookup is leading to a timeout, and cause the problem mentioned above.
--------------------------------------------------------------------------
Looks like 'EVENTLET_NO_GREENDNS' option is disabled only in eventlet 0.20.0~0.20.1, and it's back in 0.21.0.
But for now eventlet 0.20.0 (from global-requirements) is used by all openstack services, temporarily we need to change the install guide for nodes to work well under greened dns:
1. put a usable nameserver in resolv.conf on all nodes that install guide mentioned.
2. or map both ipv4 and ipv6 address for rabbitmq server(e.g. controller) in /etc/hosts.
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References