vdombrovski opened a new issue, #8967:
URL: https://github.com/apache/cloudstack/issues/8967
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##### ISSUE TYPE
<!-- Pick one below and delete the rest -->
* Bug Report
##### COMPONENT NAME
<!--
Categorize the issue, e.g. API, VR, VPN, UI, etc.
-->
~~~
VR
~~~
##### CLOUDSTACK VERSION
<!--
New line separated list of affected versions, commit ID for issues on main
branch.
-->
~~~
4.17.2
~~~
Note: I believe this impacts releases 4.18 and 4.19 also as no relevant code
changes have been made to VR code
##### CONFIGURATION
<!--
Information about the configuration if relevant, e.g. basic network,
advanced networking, etc. N/A otherwise
-->
- Advanced zone
- Standard networking using virtual routers only
- /24 pool of "public" IPs available for the virtual routers
##### OS / ENVIRONMENT
<!--
Information about the environment if relevant, N/A otherwise
-->
Ubuntu Focal 20.04
##### SUMMARY
<!-- Explain the problem/feature briefly -->
Our workflow makes it so public IPs can be assigned/unassigned/reassigned to
different networks, possibly multiple times per day (mostly, but not only via
https://github.com/apache/cloudstack-kubernetes-provider)
After a while, we started seeing that many unused IP addresses (according to
ACS database) were actually answering to L2 ARPing. In parallel, some of our
IPs are getting 2 different MACs from the ping:
```
ARPING XX.YY.25.156
60 bytes from 1e:00:fe:00:04:ac (XX.YY.25.156): index=0 time=306.714 usec
60 bytes from 1e:00:63:00:04:b5 (XX.YY.25.156): index=1 time=342.809 usec
```
Our investigation has shown these conflicts on around 10 ips in two of our
/24 subnets, which looks too much to be a conicidence.
We have confirmed that both MAC addresses belong to alive and healthy
virtual routers:
```
[cloud]> select instance_id from nics where mac_address="1e:00:63:00:04:b5";
+-------------+
| instance_id |
+-------------+
| 5654 |
+-------------+
1 row in set (0.010 sec)
[cloud]> select instance_id from nics where mac_address="1e:00:fe:00:04:ac";
+-------------+
| instance_id |
+-------------+
| 5624 |
+-------------+
1 row in set (0.007 sec)
```
These routers both correctly mount the IP addresses:
```
ip a | grep XX.YY.25.156
inet XX.YY.25.156/24 brd XX.YY.25.255 scope global secondary eth2
```
Inside the "databag" of the so called "illegitimate" router causing the
conflict, we can see the IP declared (sometimes with flag add: true, sometimes
with add: false):
```
# /etc/cloudstack/ips.json
{
"add": true,
"broadcast": "XX.YY.25.255",
"cidr": "XX.YY.25.156/24",
"device": "eth2",
"first_i_p": false,
"gateway": "XX.YY.25.1",
"is_private_gateway": false,
"netmask": "255.255.255.0",
"network": "XX.YY.25.0/24",
"new_nic": false,
"nic_dev_id": 2,
"nw_type": "public",
"one_to_one_nat": false,
"public_ip": "XX.YY.25.156",
"size": "24",
"source_nat": false,
"vif_mac_address": "1e:00:63:00:04:b5"
}
```
To my understanding, this file is read/merged whenever a new IP state change
is requested; however it's not merged properly on unassignment.
Obviously, deleting/recreating all the virtual routers would solve the issue
as this cache would be cleared; however because this causes massive disruptions
on the service we would like to make sure the root cause is fixed first.
##### STEPS TO REPRODUCE
<!--
For bugs, show exactly how to reproduce the problem, using a minimal
test-case. Use Screenshots if accurate.
For new features, show how the feature would be used.
-->
No specific command line here, but I think trying to bounce a public IP
between 2 guest routers (ofc inside separate VPCs if these are VPC networks)
several time would results in this issue.
1. Create 2 guest networks A and B
2. Create 2 VMS, one inside network A, the other inside network B
3. Associate an IP address to network A, and create a loadbalancer rule for
some port of VM A (should also work with port-forwarding and static NAT)
4. Release the IP, associate it to network B, and create a loadbalancer rule
for some port of VM A (should also work with port-forwarding and static NAT)
5. Repeat steps 3-4 until you get an IP address conflict (or until you see
invalid entries in the databag)
##### EXPECTED RESULTS
<!-- What did you expect to happen when running the steps above? -->
The IP is properly garbage collected on the router that doesn't hold it
anymore
##### ACTUAL RESULTS
<!-- What actually happened? -->
<!-- Paste verbatim command output between quotes below -->
IP address conflcit
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