Ansible Role for Flanneld

This Ansible playbook is used to set up and configure the flanneld binary, which is part of Kubernetes. Flannel provides a layer 3 IPv4 network for different nodes in a cluster. It manages how traffic moves between hosts but not how containers connect to the host. Flannel also includes a CNI plugin for Kubernetes and offers guidance on integrating with Docker.

Versions

Every release is tagged, and I follow semantic versioning. I recommend using the latest tag for the role. The main branch is for development, and tags indicate stable releases. For example, 8.0.0+0.16.1 shows that this role is version 8.0.0 designed for Flannel version 0.16.1 (it might work with newer versions as well). If the role updates, the part before + will increase. If the Flannel version changes, the part after + will increase. This way, I can tag bug fixes and major updates while still developing for a specific Flannel version.

Requirements

• A running etcd cluster (see ansible-role-etcd). The role connects to the first node in Ansible's k8s_etcd group to add a new entry in etcd with the Flannel network configuration located at "flannel_etcd_prefix/config".
• CNI plugins (see ansible-role-cni).

Changelog

Check the CHANGELOG.md for updates.

Role Variables

Here are some key variables you can set:

k8s_interface: "tap0"  # The interface for K8s services
k8s_conf_dir: "/var/lib/kubernetes"  # Directory for K8s configuration
k8s_cni_conf_dir: "/etc/cni/net.d"  # CNI plugin directory
k8s_ca_conf_directory: "{{ '~/k8s/certs' | expanduser }}"  # Directory for K8s certificates

flannel_version: "v0.16.1"  # Flannel version
flannel_etcd_prefix: "/kubernetes-cluster/network"  # etcd path for Flannel settings
flannel_ip_range: "10.200.0.0/16"  # IP range for Flannel
flannel_backend_type: "vxlan"  # Backend type for Flannel
flannel_cni_interface: "cni0"  # CNI interface name

You can override flannel_settings by creating a variable called flannel_settings_user to add or modify settings.

Important Note

There's a commented-out directive, flannel_systemd_execstartpost: "/sbin/ethtool -K flannel.1 tx off". If Pod-to-Pod communication works but Pod-to-Service or Node-to-Service doesn’t, enabling this may help, especially on Hetzner cloud. It addresses a checksum issue with traffic.

Dependencies

• etcd (see ansible-role-etcd)
• CNI plugins (see ansible-role-cni or other roles that install CNI plugins)

Example Playbook

You can use this example to run the playbook:

- hosts: flannel
  roles:
    - githubixx.flanneld

License

This work is licensed under the GNU GENERAL PUBLIC LICENSE Version 3.

Author Information

For more information, visit http://www.tauceti.blog.