ansible-role-kubernetes-worker

This Ansible role is used in Kubernetes the not so hard way with Ansible - Worker. This Ansible role setup Kubernetes worker nodes. For more information please see Kubernetes the not so hard way with Ansible - Worker.

Versions

I tag every release and try to stay with semantic versioning. If you want to use the role I recommend to checkout the latest tag. The master branch is basically development while the tags mark stable releases. But in general I try to keep master in good shape too. A tag 27.0.0+1.30.5 means this is release 27.0.0 of this role and it's meant to be used with Kubernetes version 1.30.5 (but should work with any K8s 1.27.x release of course). If the role itself changes X.Y.Z before + will increase. If the Kubernetes version changes X.Y.Z after + will increase too. This allows to tag bugfixes and new major versions of the role while it's still developed for a specific Kubernetes release. That's especially useful for Kubernetes major releases with breaking changes.

Requirements

This playbook expects that you already have rolled out the Kubernetes controller components (see kubernetes-controller and Kubernetes the not so hard way with Ansible - Control plane.

You also need containerd, CNI plugins and runc installed. To enable Kubernetes Pods to communicate between different hosts it makes sense to install Cilium later once the worker nodes are running e.g. Of course Calico, WeaveNet, kube-router or flannel or other Kubernetes network solutions are valid options.

Supported OS

• Ubuntu 20.04 (Focal Fossa) (reaches EOL April 2024 - not recommended)
• Ubuntu 22.04 (Jammy Jellyfish)
• Ubuntu 24.04 (Noble Numbat) (recommended)

Changelog

Change history:

See full CHANGELOG.md

IMPORTANT Version 24.0.0+1.27.8 had a lot of potential breaking changes. So if you upgrade from a version < 24.0.0+1.27.8 please read the CHANGELOG of that version too!

Recent changes:

27.0.0+1.30.5

• UPDATE

  • update k8s_worker_release to 1.30.5

• OTHER CHANGES

  • support Ubuntu 24.04
  • update .yamllint

26.0.2+1.29.9

• OTHER CHANGES
  • fix download URLs for Kubernetes binaries (see: Download Kubernetes - Binaries

26.0.1+1.29.9

• UPDATE
  • update k8s_release to 1.29.9

26.0.0+1.29.4

• UPDATE

  • update k8s_release to 1.29.4

• MOLECULE

  • use alvistack instead of generic Vagrant boxes

Installation

• Directly download from Github (Change into Ansible roles directory before cloning. You can figure out the role path by using ansible-config dump | grep DEFAULT_ROLES_PATH command): git clone https://github.com/githubixx/ansible-role-kubernetes-worker.git githubixx.kubernetes_worker

• Via ansible-galaxy command and download directly from Ansible Galaxy: ansible-galaxy install role githubixx.kubernetes_worker

• Create a requirements.yml file with the following content (this will download the role from Github) and install with ansible-galaxy role install -r requirements.yml (change version if needed):

---
roles:
  - name: githubixx.kubernetes_worker
    src: https://github.com/githubixx/ansible-role-kubernetes-worker.git
    version: 27.0.0+1.30.5

Role Variables

# The base directory for Kubernetes configuration and certificate files for
# everything worker nodes related. After the playbook is done this directory
# contains various sub-folders.
k8s_worker_conf_dir: "/etc/kubernetes/worker"

# All certificate files (Private Key Infrastructure related) specified in
# "k8s_worker_certificates" (see "vars/main.yml") will be stored here.
# Owner and group of this new directory will be "root". File permissions
# will be "0640".
k8s_worker_pki_dir: "{{ k8s_worker_conf_dir }}/pki"

# The directory to store the Kubernetes binaries (see "k8s_worker_binaries"
# variable in "vars/main.yml"). Owner and group of this new directory
# will be "root" in both cases. Permissions for this directory will be "0755".
#
# NOTE: The default directory "/usr/local/bin" normally already exists on every
# Linux installation with the owner, group and permissions mentioned above. If
# your current settings are different consider a different directory. But make sure
# that the new directory is included in your "$PATH" variable value.
k8s_worker_bin_dir: "/usr/local/bin"

# K8s release
k8s_worker_release: "1.30.5"

# The interface on which the Kubernetes services should listen on. As all cluster
# communication should use a VPN interface the interface name is
# normally "wg0" (WireGuard),"peervpn0" (PeerVPN) or "tap0".
#
# The network interface on which the Kubernetes worker services should
# listen on. That is:
#
# - kube-proxy
# - kubelet
#
k8s_interface: "eth0"

# The directory from where to copy the K8s certificates. By default this
# will expand to user's LOCAL $HOME (the user that run's "ansible-playbook ..."
# plus "/k8s/certs". That means if the user's $HOME directory is e.g.
# "/home/da_user" then "k8s_ca_conf_directory" will have a value of
# "/home/da_user/k8s/certs".
k8s_ca_conf_directory: "{{ '~/k8s/certs' | expanduser }}"

# The IP address or hostname of the Kubernetes API endpoint. This variable
# is used by "kube-proxy" and "kubelet" to connect to the "kube-apiserver"
# (Kubernetes API server).
#
# By default the first host in the Ansible group "k8s_controller" is
# specified here. NOTE: This setting is not fault tolerant! That means
# if the first host in the Ansible group "k8s_controller" is down
# the worker node and its workload continue working but the worker
# node doesn't receive any updates from Kubernetes API server.
#
# If you have a loadbalancer that distributes traffic between all
# Kubernetes API servers it should be specified here (either its IP
# address or the DNS name). But you need to make sure that the IP
# address or the DNS name you want to use here is included in the
# Kubernetes API server TLS certificate (see "k8s_apiserver_cert_hosts"
# variable of https://github.com/githubixx/ansible-role-kubernetes-ca
# role). If it's not specified you'll get certificate errors in the
# logs of the services mentioned above.
k8s_worker_api_endpoint_host: "{% set controller_host = groups['k8s_controller'][0] %}{{ hostvars[controller_host]['ansible_' + hostvars[controller_host]['k8s_interface']].ipv4.address }}"

# As above just for the port. It specifies on which port the
# Kubernetes API servers are listening. Again if there is a loadbalancer
# in place that distributes the requests to the Kubernetes API servers
# put the port of the loadbalancer here.
k8s_worker_api_endpoint_port: "6443"

# OS packages needed on a Kubernetes worker node. You can add additional
# packages at any time. But please be aware if you remove one or more from
# the default list your worker node might not work as expected or doesn't work
# at all.
k8s_worker_os_packages:
  - ebtables
  - ethtool
  - ipset
  - conntrack
  - iptables
  - iptstate
  - netstat-nat
  - socat
  - netbase

# Directory to store kubelet configuration
k8s_worker_kubelet_conf_dir: "{{ k8s_worker_conf_dir }}/kubelet"

# kubelet settings
#
# If you want to enable the use of "RuntimeDefault" as the default seccomp
# profile for all workloads add these settings to "k8s_worker_kubelet_settings":
#
# "seccomp-default": ""
#
# Also see:
# https://kubernetes.io/docs/tutorials/security/seccomp/#enable-the-use-of-runtimedefault-as-the-default-seccomp-profile-for-all-workloads
k8s_worker_kubelet_settings:
  "config": "{{ k8s_worker_kubelet_conf_dir }}/kubelet-config.yaml"
  "node-ip": "{{ hostvars[inventory_hostname]['ansible_' + k8s_interface].ipv4.address }}"
  "kubeconfig": "{{ k8s_worker_kubelet_conf_dir }}/kubeconfig"

# kubelet kubeconfig
k8s_worker_kubelet_conf_yaml: |
  kind: KubeletConfiguration
  apiVersion: kubelet.config.k8s.io/v1beta1
  address: {{ hostvars[inventory_hostname]['ansible_' + k8s_interface].ipv4.address }}
  authentication:
    anonymous:
      enabled: false
    webhook:
      enabled: true
    x509:
      clientCAFile: "{{ k8s_worker_pki_dir }}/ca-k8s-apiserver.pem"
  authorization:
    mode: Webhook
  clusterDomain: "cluster.local"
  clusterDNS:
    - "10.32.0.254"
  failSwapOn: true
  healthzBindAddress: "{{ hostvars[inventory_hostname]['ansible_' + k8s_interface].ipv4.address }}"
  healthzPort: 10248
  runtimeRequestTimeout: "15m"
  serializeImagePulls: false
  tlsCertFile: "{{ k8s_worker_pki_dir }}/cert-{{ inventory_hostname }}.pem"
  tlsPrivateKeyFile: "{{ k8s_worker_pki_dir }}/cert-{{ inventory_hostname }}-key.pem"
  cgroupDriver: "systemd"
  registerNode: true
  containerRuntimeEndpoint: "unix:///run/containerd/containerd.sock"

# Directory to store kube-proxy configuration
k8s_worker_kubeproxy_conf_dir: "{{ k8s_worker_conf_dir }}/kube-proxy"

# kube-proxy settings
k8s_worker_kubeproxy_settings:
  "config": "{{ k8s_worker_kubeproxy_conf_dir }}/kubeproxy-config.yaml"

k8s_worker_kubeproxy_conf_yaml: |
  kind: KubeProxyConfiguration
  apiVersion: kubeproxy.config.k8s.io/v1alpha1
  bindAddress: {{ hostvars[inventory_hostname]['ansible_' + k8s_interface].ipv4.address }}
  clientConnection:
    kubeconfig: "{{ k8s_worker_kubeproxy_conf_dir }}/kubeconfig"
  healthzBindAddress: {{ hostvars[inventory_hostname]['ansible_' + k8s_interface].ipv4.address }}:10256
  mode: "ipvs"
  ipvs:
    minSyncPeriod: 0s
    scheduler: ""
    syncPeriod: 2s
  iptables:
    masqueradeAll: true
  clusterCIDR: "10.200.0.0/16"

Dependencies

• kubernetes_controller
• containerd
• runc
• CNI plugins

Example Playbook

- hosts: k8s_worker
  roles:
    - githubixx.kubernetes_worker

Testing

This role has a small test setup that is created using Molecule, libvirt (vagrant-libvirt) and QEMU/KVM. Please see my blog post Testing Ansible roles with Molecule, libvirt (vagrant-libvirt) and QEMU/KVM how to setup. The test configuration is here.

Afterwards Molecule can be executed. This will setup a few virtual machines (VM) with supported Ubuntu OS and installs a Kubernetes cluster:

molecule converge

At this time the cluster isn't fully functional as a network plugin is missing e.g. So Pod to Pod communication between two different nodes isn't possible yet. To fix this the following command can be used to install Cilium for all Kubernetes networking needs and CoreDNS for Kubernetes DNS stuff:

molecule converge -- --extra-vars k8s_worker_setup_networking=install

After this you basically have a fully functional Kubernetes cluster.

A small verification step is also included:

molecule verify

To clean up run

molecule destroy

License

GNU GENERAL PUBLIC LICENSE Version 3

Author Information

http://www.tauceti.blog