Updating plugin README.md files (#549)
Removing content and pointing at the new website as a part of the CNI Documentation migration. Signed-off-by: Nate W <4453979+nate-double-u@users.noreply.github.com>
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Nate W
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# flannel plugin
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## Overview
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This plugin is designed to work in conjunction with [flannel](https://github.com/coreos/flannel), a network fabric for containers.
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When flannel daemon is started, it outputs a `/run/flannel/subnet.env` file that looks like this:
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```
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FLANNEL_NETWORK=10.1.0.0/16
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FLANNEL_SUBNET=10.1.17.1/24
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FLANNEL_MTU=1472
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FLANNEL_IPMASQ=true
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```
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This document has moved to the [containernetworking/cni.dev](https://github.com/containernetworking/cni.dev) repo.
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This information reflects the attributes of flannel network on the host.
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The flannel CNI plugin uses this information to configure another CNI plugin, such as bridge plugin.
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You can find it online here: https://cni.dev/plugins/meta/flannel/
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## Operation
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Given the following network configuration file and the contents of `/run/flannel/subnet.env` above,
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```
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{
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"name": "mynet",
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"type": "flannel"
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}
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```
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the flannel plugin will generate another network configuration file:
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```
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{
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"name": "mynet",
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"type": "bridge",
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"mtu": 1472,
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"ipMasq": false,
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"isGateway": true,
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"ipam": {
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"type": "host-local",
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"subnet": "10.1.17.0/24"
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}
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}
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```
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It will then invoke the bridge plugin, passing it the generated configuration.
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As can be seen from above, the flannel plugin, by default, will delegate to the bridge plugin.
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If additional configuration values need to be passed to the bridge plugin, it can be done so via the `delegate` field:
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```
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{
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"name": "mynet",
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"type": "flannel",
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"delegate": {
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"bridge": "mynet0",
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"mtu": 1400
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}
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}
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```
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This supplies a configuration parameter to the bridge plugin -- the created bridge will now be named `mynet0`.
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Notice that `mtu` has also been specified and this value will not be overwritten by flannel plugin.
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Additionally, the `delegate` field can be used to select a different kind of plugin altogether.
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To use `ipvlan` instead of `bridge`, the following configuration can be specified:
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```
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{
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"name": "mynet",
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"type": "flannel",
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"delegate": {
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"type": "ipvlan",
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"master": "eth0"
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}
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}
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```
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The `ipam` part of the network configuration generated for the delegated plugin, can also be customized by adding a base `ipam` section to the input flannel network configuration. This `ipam` element is then updated with the flannel subnet, a route to the flannel network and, unless provided, an `ipam` `type` set to `host-local` before being provided to the delegated plugin.
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## Network configuration reference
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* `name` (string, required): the name of the network
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* `type` (string, required): "flannel"
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* `subnetFile` (string, optional): full path to the subnet file written out by flanneld. Defaults to /run/flannel/subnet.env
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* `dataDir` (string, optional): path to directory where plugin will store generated network configuration files. Defaults to `/var/lib/cni/flannel`
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* `delegate` (dictionary, optional): specifies configuration options for the delegated plugin.
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* `ipam` (dictionary, optional, Linux only): when specified, is used as basis to construct the `ipam` section of the delegated plugin configuration.
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flannel plugin will always set the following fields in the delegated plugin configuration:
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* `name`: value of its "name" field.
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* `ipam`: based on the received `ipam` section if present, with a `type` defaulting to `host-local`, a `subnet` set to `$FLANNEL_SUBNET` and (Linux only) a `routes` element assembled from the routes listed in the received `ipam` element and a route to the flannel network. Other fields present in the input `ipam` section will be transparently provided to the delegate.
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flannel plugin will set the following fields in the delegated plugin configuration if they are not present:
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* `ipMasq`: the inverse of `$FLANNEL_IPMASQ`
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* `mtu`: `$FLANNEL_MTU`
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Additionally, for the bridge plugin, `isGateway` will be set to `true`, if not present.
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One use case of the `ipam` configuration is to allow adding back the routes to the cluster services and/or to the hosts when using `isDefaultGateway=false`. In that case, the bridge plugin does not install a default route and, as a result, only pod-to-pod connectivity would be available.
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## Windows Support (Experimental)
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This plugin supports delegating to the windows CNI plugins (overlay.exe, l2bridge.exe) to work in conjunction with [Flannel on Windows](https://github.com/coreos/flannel/issues/833).
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Flannel sets up an [HNS Network](https://docs.microsoft.com/en-us/virtualization/windowscontainers/container-networking/architecture) in L2Bridge mode for host-gw and in Overlay mode for vxlan.
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The following fields must be set in the delegated plugin configuration:
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* `name` (string, required): the name of the network (must match the name in Flannel config / name of the HNS network)
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* `type` (string, optional): set to `win-l2bridge` by default. Can be set to `win-overlay` or other custom windows CNI
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* `ipMasq`: the inverse of `$FLANNEL_IPMASQ`
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* `endpointMacPrefix` (string, optional): required for `win-overlay` mode, set to the MAC prefix configured for Flannel
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* `clusterNetworkPrefix` (string, optional): required for `win-l2bridge` mode, setup NAT if `ipMasq` is set to true
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For `win-l2bridge`, the Flannel CNI plugin will set:
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* `ipam`: "host-local" type will be used with "subnet" set to `$FLANNEL_SUBNET` and gateway as the .2 address in `$FLANNEL_NETWORK`
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For `win-overlay`, the Flannel CNI plugin will set:
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* `ipam`: "host-local" type will be used with "subnet" set to `$FLANNEL_SUBNET` and gateway as the .1 address in `$FLANNEL_NETWORK`
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If IPMASQ is true, the Flannel CNI plugin will setup an OutBoundNAT policy and add FLANNEL_SUBNET to any existing exclusions.
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All other delegate config e.g. other HNS endpoint policies in AdditionalArgs will be passed to WINCNI as-is.
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Example VXLAN Flannel CNI config
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```
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{
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"name": "mynet",
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"type": "flannel",
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"delegate": {
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"type": "win-overlay",
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"endpointMacPrefix": "0E-2A"
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}
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}
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```
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For this example, Flannel CNI would generate the following config to delegate to the windows CNI when FLANNEL_NETWORK=10.244.0.0/16, FLANNEL_SUBNET=10.244.1.0/24 and IPMASQ=true
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```
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{
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"name": "mynet",
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"type": "win-overlay",
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"endpointMacPrefix": "0E-2A",
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"ipMasq": true,
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"ipam": {
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"subnet": "10.244.1.0/24",
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"type": "host-local"
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}
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}
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```
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