dsk-dev kubespray 이동

ansible/kubespray/docs/flannel.md

@@ -0,0 +1,51 @@
+# Flannel
+
+Flannel is a network fabric for containers, designed for Kubernetes
+
+Supported [backends](https://github.com/flannel-io/flannel/blob/master/Documentation/backends.md#wireguard): `vxlan`, `host-gw` and `wireguard`
+
+**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
+
+* Flannel configuration file should have been created there
+
+```ShellSession
+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
+
+```ShellSession
+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
+
+```ShellSession
+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
+```
+
+```ShellSession
+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
+```