VPP CNI Library Intro

VPP CNI Library is written in GO and used by UserSpace CNI to interface with the VPP GO-API. The UserSpace CNI is a CNI implementation designed to implement User Space networking (as apposed to kernel space networking), like DPDK based applications. For example VPP and OVS-DPDK.

The UserSpace CNI, based on the input config data, uses this library to add interfaces (memif and vhost-user interface) to a local VPP instance running on the host and add that interface to a local network, like a L2 Bridge. The UserSpace CNI then processes config data intended for the container and uses this library to add that data to a Database the container can consume.

UserSpace CNI README.md describes how to test with VPP CNI. Below are a few notes regarding packages in this sub-folder.

usrsp-app

The usrsp-app is intended to run in a container. It leverages the VPP CNI code to consume interfaces in the container.

cnivpp/localdb.go

localdb is use to store data in a DB. For the local VPP instance, the localdb is used to store the swIndex generated when the interface is created. It is used later to delete the interface. The usrspdb is used to pass configuration data to the container so the container can consume the interface.

The initial implementation of the DB is just json data written to a file. This can be expanded at a later date to write to something like an etcd DB.

The following filenames and directory structure is used to store the data:

• Host:

  • /var/lib/cni/usrspcni/data/:

    • local-ContainerId:12-.json: Used to store local data needed to delete and cleanup.

  • /var/lib/cni/usrspcni/shared/: Not a database directory, but this directory is used for interface socket files, for example: memif-ContainerId:12-.sock This directory is mapped into that container as the same directory in the container.

  • /var/lib/cni/usrspcni//: This directory is mapped into that container as /var/lib/cni/usrspcni/data/, so appears to the container as its local data directory. This is where the container writes its local-ContainerId:12-.json file described above.

    • remote-ContainerId:12-.json: This file contains the configuration to apply the interface in the container. The data is the same json data passed into the UserSpace CNI (define in user-space-net-plugin/pkg/types/types.go), but the Container data has been copied into the Host data label. The usrsp-app processes the data as local data. Once this data is read in the container, the usrsp-app deletes the file.
    • addData-ContainerId:12-.json: This file is used to pass additional data into the the container, which is not defined by pkg/types/types.go. This includes the ContainerId itself, and the results from the IPAM plugin that were processed locally. Once this data is read in the container, the usrsp-app deletes the file.

• Container:

  • /var/lib/cni/usrspcni/data/: Mapped from /var/lib/cni/usrspcni/container/ on the host.
  • /var/lib/cni/usrspcni/shared/: Mapped from /var/lib/cni/usrspcni/shared/ on the host.