52 lines
1.8 KiB
Markdown
52 lines
1.8 KiB
Markdown
# Flannel
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Flannel is a network fabric for containers, designed for Kubernetes
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Supported [backends](https://github.com/flannel-io/flannel/blob/master/Documentation/backends.md#wireguard): `vxlan`, `host-gw` and `wireguard`
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**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).
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## 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
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FLANNEL_NETWORK=10.233.0.0/18
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FLANNEL_SUBNET=10.233.16.1/24
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FLANNEL_MTU=1450
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FLANNEL_IPMASQ=false
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```
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* Check if the network interface has been created
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```ShellSession
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ip a show dev flannel.1
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4: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default
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link/ether e2:f3:a7:0f:bf:cb brd ff:ff:ff:ff:ff:ff
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inet 10.233.16.0/18 scope global flannel.1
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valid_lft forever preferred_lft forever
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inet6 fe80::e0f3:a7ff:fe0f:bfcb/64 scope link
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valid_lft forever preferred_lft forever
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```
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* 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
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replicationcontroller "test" created
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kubectl describe po test-34ozs | grep ^IP
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IP: 10.233.16.2
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```
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```ShellSession
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kubectl exec test-34ozs -- ip a show dev eth0
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8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1450 qdisc noqueue
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link/ether 02:42:0a:e9:2b:03 brd ff:ff:ff:ff:ff:ff
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inet 10.233.16.2/24 scope global eth0
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valid_lft forever preferred_lft forever
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inet6 fe80::42:aff:fee9:2b03/64 scope link tentative flags 08
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valid_lft forever preferred_lft forever
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```
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