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# Flannel
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2020-04-15 14:48:02 +08:00
Flannel is a network fabric for containers, designed for Kubernetes
**Warning:** You may encounter this [bug ](https://github.com/coreos/flannel/pull/1282 ) with `VXLAN` backend, while waiting on a newer Flannel version the current workaround (`ethtool --offload flannel.1 rx off tx off`) is showcase in kubespray [networking test ](tests/testcases/040_check-network-adv.yml:31 ).
## Verifying flannel install
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* Flannel configuration file should have been created there
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```ShellSession
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cat /run/flannel/subnet.env
FLANNEL_NETWORK=10.233.0.0/18
FLANNEL_SUBNET=10.233.16.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=false
```
* Check if the network interface has been created
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```ShellSession
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ip a show dev flannel.1
4: flannel.1: < BROADCAST , MULTICAST , UP , LOWER_UP > mtu 1450 qdisc noqueue state UNKNOWN group default
link/ether e2:f3:a7:0f:bf:cb brd ff:ff:ff:ff:ff:ff
inet 10.233.16.0/18 scope global flannel.1
valid_lft forever preferred_lft forever
inet6 fe80::e0f3:a7ff:fe0f:bfcb/64 scope link
valid_lft forever preferred_lft forever
```
* Try to run a container and check its ip address
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```ShellSession
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kubectl run test --image=busybox --command -- tail -f /dev/null
replicationcontroller "test" created
kubectl describe po test-34ozs | grep ^IP
IP: 10.233.16.2
```
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```ShellSession
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kubectl exec test-34ozs -- ip a show dev eth0
8: eth0@if9: < BROADCAST , MULTICAST , UP , LOWER_UP , M-DOWN > mtu 1450 qdisc noqueue
link/ether 02:42:0a:e9:2b:03 brd ff:ff:ff:ff:ff:ff
inet 10.233.16.2/24 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::42:aff:fee9:2b03/64 scope link tentative flags 08
valid_lft forever preferred_lft forever
```
