XTesting/kubespray/docs/flannel.md

   1 # Flannel
   2
   3 Flannel is a network fabric for containers, designed for Kubernetes
   4
   5 **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).
   6
   7 ## Verifying flannel install
   8
   9 * Flannel configuration file should have been created there
  10
  11 ```ShellSession
  12 cat /run/flannel/subnet.env
  13 FLANNEL_NETWORK=10.233.0.0/18
  14 FLANNEL_SUBNET=10.233.16.1/24
  15 FLANNEL_MTU=1450
  16 FLANNEL_IPMASQ=false
  17 ```
  18
  19 * Check if the network interface has been created
  20
  21 ```ShellSession
  22 ip a show dev flannel.1
  23 4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default
  24     link/ether e2:f3:a7:0f:bf:cb brd ff:ff:ff:ff:ff:ff
  25     inet 10.233.16.0/18 scope global flannel.1
  26        valid_lft forever preferred_lft forever
  27     inet6 fe80::e0f3:a7ff:fe0f:bfcb/64 scope link
  28        valid_lft forever preferred_lft forever
  29 ```
  30
  31 * Try to run a container and check its ip address
  32
  33 ```ShellSession
  34 kubectl run test --image=busybox --command -- tail -f /dev/null
  35 replicationcontroller "test" created
  36
  37 kubectl describe po test-34ozs | grep ^IP
  38 IP:                             10.233.16.2
  39 ```
  40
  41 ```ShellSession
  42 kubectl exec test-34ozs -- ip a show dev eth0
  43 8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1450 qdisc noqueue
  44     link/ether 02:42:0a:e9:2b:03 brd ff:ff:ff:ff:ff:ff
  45     inet 10.233.16.2/24 scope global eth0
  46        valid_lft forever preferred_lft forever
  47     inet6 fe80::42:aff:fee9:2b03/64 scope link tentative flags 08
  48        valid_lft forever preferred_lft forever
  49 ```