Public bug reported:
If I use heat to create a set of networks, each with its own subnet,
sometimes I will get an error from Neutron that there is an overlap.
There is an example heat template attached. In my environment, this will
fail about 1 or 2 times in 10.
The heat template does:
for X in seq 0 10
create network X
assign subnet 172.16.X.0/24 to network X
One of the stacks will get an error on one of the subnets, indicating:
Requested Subnet With Cidr: 172.16.7.0/24 For Network: 73f99807-0b2a-
49d3-8d11-B7bd74d02f4d Overlaps With Another Subnet.
This is in turn coming from _validate_subnet_cidr() in db/ipam_backend_mixin.py.
What is happening is that the 'new_subnet_cidr' passed in is matching against
itself.
Since I have 'allow_overlapping_ips=true', it does:
subnet_list = network.subnets
but, in the failure case, this subnet is already there. In the 'no
failure case' it is not yet there.
I have 3 heat API servers, and 72 heat workers (3 servers). The api
servers are round-robin load balanced
I just (2016-06-24) reproduced this against the master/head from github
(so midway between mitaka and newton).
I'm not sure if there is some missing locking, but for sure this is a
race condition.
I have ipam_driver unset
If i comment out the exception in _validate_subnet_cidr() then it works
OK.
** Affects: neutron
Importance: Undecided
Status: New
** Attachment added: "Example heat template"
https://bugs.launchpad.net/bugs/1596075/+attachment/4689902/+files/t.yml
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https://bugs.launchpad.net/bugs/1596075
Title:
Neutron confused about overlapping subnet creation
Status in neutron:
New
Bug description:
If I use heat to create a set of networks, each with its own subnet,
sometimes I will get an error from Neutron that there is an overlap.
There is an example heat template attached. In my environment, this
will fail about 1 or 2 times in 10.
The heat template does:
for X in seq 0 10
create network X
assign subnet 172.16.X.0/24 to network X
One of the stacks will get an error on one of the subnets, indicating:
Requested Subnet With Cidr: 172.16.7.0/24 For Network: 73f99807-0b2a-
49d3-8d11-B7bd74d02f4d Overlaps With Another Subnet.
This is in turn coming from _validate_subnet_cidr() in
db/ipam_backend_mixin.py.
What is happening is that the 'new_subnet_cidr' passed in is matching against
itself.
Since I have 'allow_overlapping_ips=true', it does:
subnet_list = network.subnets
but, in the failure case, this subnet is already there. In the 'no
failure case' it is not yet there.
I have 3 heat API servers, and 72 heat workers (3 servers). The api
servers are round-robin load balanced
I just (2016-06-24) reproduced this against the master/head from
github (so midway between mitaka and newton).
I'm not sure if there is some missing locking, but for sure this is a
race condition.
I have ipam_driver unset
If i comment out the exception in _validate_subnet_cidr() then it
works OK.
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https://bugs.launchpad.net/neutron/+bug/1596075/+subscriptions
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