cnitool

cnitool

cnitool is a simple program that executes a CNI configuration. It will add or remove an interface in an already-created network namespace.

Environment Variables

• NETCONFPATH: This environment variable needs to be set to a directory. It defaults to /etc/cni/net.d. The cnitool searches for CNI configuration files in this directory according to the following priorities:

  1. Search files with the extension *.conflist, representing a list of plugin configurations.
  2. If there are no *.conflist files in the directory, search files with the extension *.conf or *.json, representing a single plugin configuration.

  It loads all the CNI configuration files in this directory and if it finds a CNI configuration with the network name given to the cnitool it returns the corresponding CNI configuration, else it returns nil.

• CNI_PATH: For a given CNI configuration cnitool will search for the corresponding CNI plugin in this path.

Example invocation

First, install cnitool:

go get github.com/containernetworking/cni
go install github.com/containernetworking/cni/cnitool

Then, check out and build the plugins. All commands should be run from this directory.

git clone https://github.com/containernetworking/plugins.git
cd plugins
./build_linux.sh
# or
./build_windows.sh

Create a network configuration

echo '{"cniVersion":"0.4.0","name":"myptp","type":"ptp","ipMasq":true,"ipam":{"type":"host-local","subnet":"172.16.29.0/24","routes":[{"dst":"0.0.0.0/0"}]}}' | sudo tee /etc/cni/net.d/10-myptp.conf

Create a network namespace. This will be called testing:

sudo ip netns add testing

Add the container to the network:

sudo CNI_PATH=./bin cnitool add myptp /var/run/netns/testing

Check whether the container's networking is as expected (ONLY for spec v0.4.0+):

sudo CNI_PATH=./bin cnitool check myptp /var/run/netns/testing

Test that it works:

sudo ip -n testing addr
sudo ip netns exec testing ping -c 1 4.2.2.2

And clean up:

sudo CNI_PATH=./bin cnitool del myptp /var/run/netns/testing
sudo ip netns del testing