** Also affects: openstack-manuals
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1717707
Title:
EVENTLET_NO_GREENDNS is disabled in eventlet 0.20.*, nameserver should
be configured on all nodes for name resolution
Status in OpenStack Compute (nova):
Invalid
Status in openstack-manuals:
New
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 when:
on compute node
1. no usable nameserver in /etc/resolv.conf
2. only ipv4 or only ipv6 address 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, it's back in 0.21.0.
So temporarily there are two ways for nodes to work well under greened dns:
1. put a usable nameserver in resolv.conf.
2. map both ipv4 and ipv6 address for rabbitmq server(e.g. controller) in
/etc/hosts.
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