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README.md

CNI: Post Processing: Manage neighbours on the host

This is a CNI plugin. To learn more about CNI, see cni.dev.

Overview

host-neigh manages neighbour entries on the host based on the outputs of previous plugins or its own config.

Configuration

To configure, add this plugin after other plugins. Where it goes will depend on what you want it to do.

{
  "type": "host-routes",
  "neigh": "expression",
  "tries": 3,
}

The neigh field should contain a jq expression as a string, which should evaluate to an array of Neigh objects, with these fields:

  • address (IP address as string, required): the IP of the neighbour.
  • device (string, required): the device name to add the neighbour to.
  • lladdr (MAC address or interface name as string, optional for del): the MAC address of the neighbour, or an interface/device name that will be resolved into its MAC address.

Returning an empty array is acceptable.

The jq expression is invoked with the network config as input, and is limited to 1 second running time.

tries defines how many times failing actions will be retried. Defaults to 3, caps out at 10, setting to 0 or an invalid value will use the default.

Output

This plugin takes the prevResult if present, or an empty / all-defaults one otherwise, and adds (to) a hostNeighbours array containing the Neigh objects returned by the jq expression. Note that this is not supported by libcni, which will ignore it, so is useful only as debug at this point.

Deletes

The expression will be invoked in the same way, such that the neighbours can be cleaned up.

Log file

Error and warn logs are always copied to STDERR.

The verbose flavour logs at debug level to /var/log/cni/host-routes.log.

The logging is suitable for investigating issues in production. Note that log messages may span multiple lines and that their format can change at any time.

The version of the plugin is reported at debug level on startup.

Errors

The plugin errors when:

  • the neigh field is missing or not a string.
  • it's not a valid jq expression.
  • the jq expression errors.
  • the jq evaluation times out.
  • it evaluates to an invalid structure.
  • an lladdr field is not a mac address nor an existing interface name.
  • an lladdr field is an interface name but that device does not have a MAC.