Install a CNI plugin

Estimated reading time: 2 minutes

With Docker Universal Control Plane, you can install a third-party Container Networking Interface (CNI) plugin when you install UCP, by using the --cni-installer-url option. By default, Docker EE installs the built-in Calico plugin, but you can override the default and install a plugin of your choice, like Flannel or Weave.

Install UCP with a custom CNI plugin

Modify the UCP install command-line to add the --cni-installer-url option, providing a URL for the location of the CNI plugin’s YAML file:

docker container run --rm -it --name ucp \
  -v /var/run/docker.sock:/var/run/docker.sock \
  docker/ucp:3.0.10 install \
  --host-address <node-ip-address> \
  --cni-installer-url <cni-yaml-url> \
  --interactive

You must provide a correct YAML installation file for the CNI plugin, but most of the default files work on Docker EE with no modification.

YAML files for CNI plugins

Use the following commands to get the YAML files for popular CNI plugins.

Flannel

# Get the URL for the Flannel CNI plugin.
CNI_URL="https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml"

Weave

# Get the URL for the Weave CNI plugin. 
CNI_URL="https://cloud.weave.works/k8s/net?k8s-version=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"

If you have kubectl available, for example by using Docker for Mac, you can use the following command to get the URL for the Weave CNI plugin:

# Get the URL for the Weave CNI plugin. 
CNI_URL="https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"

Romana

# Get the URL for the Romana CNI plugin.
CNI_URL="https://raw.githubusercontent.com/romana/romana/master/docs/kubernetes/romana-kubeadm.yml"

Disable IP in IP overlay tunneling

The Calico CNI plugin supports both overlay (IPIP) and underlay forwarding technologies. By default, Docker UCP uses IPIP overlay tunneling.

If you’re used to managing applications at the network level through the underlay visibility, or you want to reuse existing networking tools in the underlay, you may want to disable the IPIP functionality. Run the following commands on the Kubernetes master node to disable IPIP overlay tunneling.

# Exec into the Calico Kubernetes controller container.
docker exec -it $(docker ps --filter name=k8s_calico-kube-controllers_calico-kube-controllers -q) sh

# Download calicoctl
wget https://github.com/projectcalico/calicoctl/releases/download/v3.1.1/calicoctl

# Get the IP pool configuration. 
./calicoctl get ippool -o yaml > ippool.yaml

# Edit the file: Disable IPIP in ippool.yaml by setting "ipipMode: Never".

# Apply the edited file to the Calico plugin.
./calicoctl apply -f ippool.yaml

These steps disable overlay tunneling, and Calico uses the underlay networking, in environments where it’s supported.

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