Ansible role for installing K3S ("Lightweight Kubernetes") as either a standalone server or cluster.
Hi! 👋 @xanmanning is looking for a new maintainer to work on this Ansible role. This is because I don't have as much free time any more and I no longer write Ansible regularly as part of my day job. If you're interested, get in touch.
Please see Releases and CHANGELOG.md.
The host you're running Ansible from requires the following Python dependencies:
python >= 3.6.0- See Notes below.ansible >= 2.9.16oransible-base >= 2.10.4
You can install dependencies using the requirements.txt file in this repository:
pip3 install -r requirements.txt.
This role has been tested against the following Linux Distributions:
- Alpine Linux
- Amazon Linux 2
- Archlinux
- CentOS 8
- Debian 11
- Fedora 31
- Fedora 32
- Fedora 33
- openSUSE Leap 15
- RockyLinux 8
- Ubuntu 20.04 LTS
k3s >= v1.19, for
k3s < v1.19 please consider updating or use the v1.x releases of this role.
Before upgrading, see CHANGELOG for notifications of breaking changes.
Since K3s v1.19.1+k3s1
you can now configure K3s using a
configuration file
rather than environment variables or command line arguments. The v2 release of
this role has moved to the configuration file method rather than populating a
systemd unit file with command-line arguments. There may be exceptions that are
defined in Global/Cluster Variables, however you will
mostly be configuring k3s by configuration files using the k3s_server and
k3s_agent variables.
See "Server (Control Plane) Configuration" and "Agent (Worker) Configuraion" below.
Below are variables that are set against all of the play hosts for environment consistency. These are generally cluster-level configuration.
| Variable | Description | Default Value |
|---|---|---|
k3s_state |
State of k3s: installed, started, stopped, downloaded, uninstalled, validated. | installed |
k3s_release_version |
Use a specific version of k3s, eg. v0.2.0. Specify false for stable. |
false |
k3s_airgap |
Boolean to enable air-gapped installations | false |
k3s_config_file |
Location of the k3s configuration file. | /etc/rancher/k3s/config.yaml |
k3s_build_cluster |
When multiple play hosts are available, attempt to cluster. Read notes below. | true |
k3s_registration_address |
Fixed registration address for nodes. IP or FQDN. | NULL |
k3s_github_url |
Set the GitHub URL to install k3s from. | https://github.com/k3s-io/k3s |
k3s_api_url |
URL for K3S updates API. | https://update.k3s.io |
k3s_install_dir |
Installation directory for k3s. | /usr/local/bin |
k3s_install_hard_links |
Install using hard links rather than symbolic links. | false |
k3s_server_config_yaml_d_files |
A flat list of templates to supplement the k3s_server configuration. |
[] |
k3s_agent_config_yaml_d_files |
A flat list of templates to supplement the k3s_agent configuration. |
[] |
k3s_server_manifests_urls |
A list of URLs to deploy on the primary control plane. Read notes below. | [] |
k3s_server_manifests_templates |
A flat list of templates to deploy on the primary control plane. | [] |
k3s_server_pod_manifests_urls |
A list of URLs for installing static pod manifests on the control plane. Read notes below. | [] |
k3s_server_pod_manifests_templates |
A flat list of templates for installing static pod manifests on the control plane. | [] |
k3s_use_experimental |
Allow the use of experimental features in k3s. | false |
k3s_use_unsupported_config |
Allow the use of unsupported configurations in k3s. | false |
k3s_etcd_datastore |
Enable etcd embedded datastore (read notes below). | false |
k3s_debug |
Enable debug logging on the k3s service. | false |
k3s_registries |
Registries configuration file content. | { mirrors: {}, configs:{} } |
The below variables change how and when the systemd service unit file for K3S is run. Use this with caution, please refer to the systemd documentation for more information.
| Variable | Description | Default Value |
|---|---|---|
k3s_start_on_boot |
Start k3s on boot. | true |
k3s_service_requires |
List of required systemd units to k3s service unit. | [] |
k3s_service_wants |
List of "wanted" systemd unit to k3s (weaker than "requires"). | []* |
k3s_service_before |
Start k3s before a defined list of systemd units. | [] |
k3s_service_after |
Start k3s after a defined list of systemd units. | []* |
k3s_service_env_vars |
Dictionary of environment variables to use within systemd unit file. | {} |
k3s_service_env_file |
Location on host of a environment file to include. | false** |
* The systemd unit template always specifies network-online.target for
wants and after.
** The file must already exist on the target host, this role will not create nor manage the file. You can manage this file outside of the role with pre-tasks in your Ansible playbook.
Below are variables that are set against individual or groups of play hosts. Typically you'd set these at group level for the control plane or worker nodes.
| Variable | Description | Default Value |
|---|---|---|
k3s_control_node |
Specify if a host (or host group) are part of the control plane. | false (role will automatically delegate a node) |
k3s_server |
Server (control plane) configuration, see notes below. | {} |
k3s_agent |
Agent (worker) configuration, see notes below. | {} |
The control plane is configured with the k3s_server dict variable. Please
refer to the below documentation for configuration options:
https://rancher.com/docs/k3s/latest/en/installation/install-options/server-config/
The k3s_server dictionary variable will contain flags from the above
(removing the -- prefix). Below is an example:
k3s_server:
datastore-endpoint: postgres://postgres:verybadpass@database:5432/postgres?sslmode=disable
cluster-cidr: 172.20.0.0/16
flannel-backend: 'none' # This needs to be in quotes
disable:
- traefik
- corednsAlternatively, you can create a .yaml file and read it in to the k3s_server
variable as per the below example:
k3s_server: "{{ lookup('file', 'path/to/k3s_server.yml') | from_yaml }}"Check out the Documentation for example configuration.
Workers are configured with the k3s_agent dict variable. Please refer to the
below documentation for configuration options:
https://rancher.com/docs/k3s/latest/en/installation/install-options/agent-config
The k3s_agent dictionary variable will contain flags from the above
(removing the -- prefix). Below is an example:
k3s_agent:
with-node-id: true
node-label:
- "foo=bar"
- "hello=world"Alternatively, you can create a .yaml file and read it in to the k3s_agent
variable as per the below example:
k3s_agent: "{{ lookup('file', 'path/to/k3s_agent.yml') | from_yaml }}"Check out the Documentation for example configuration.
The below variables are used to change the way the role executes in Ansible, particularly with regards to privilege escalation.
| Variable | Description | Default Value |
|---|---|---|
k3s_skip_validation |
Skip all tasks that validate configuration. | false |
k3s_skip_env_checks |
Skip all tasks that check environment configuration. | false |
k3s_skip_post_checks |
Skip all tasks that check post execution state. | false |
k3s_become |
Escalate user privileges for tasks that need root permissions. | false |
From v3 of this role, Python 3 is required on the target system as well as on the Ansible controller. This is to ensure consistent behaviour for Ansible tasks as Python 2 is now EOL.
If target systems have both Python 2 and Python 3 installed, it is most likely
that Python 2 will be selected by default. To ensure Python 3 is used on a
target with both versions of Python, ensure ansible_python_interpreter is
set in your inventory. Below is an example inventory:
---
k3s_cluster:
hosts:
kube-0:
ansible_user: ansible
ansible_host: 10.10.9.2
ansible_python_interpreter: /usr/bin/python3
kube-1:
ansible_user: ansible
ansible_host: 10.10.9.3
ansible_python_interpreter: /usr/bin/python3
kube-2:
ansible_user: ansible
ansible_host: 10.10.9.4
ansible_python_interpreter: /usr/bin/python3If you do not set a k3s_release_version the latest version from the stable
channel of k3s will be installed. If you are developing against a specific
version of k3s you must ensure this is set in your Ansible configuration, eg:
k3s_release_version: v1.19.3+k3s1It is also possible to install specific K3s "Channels", below are some
examples for k3s_release_version:
k3s_release_version: false # defaults to 'stable' channel
k3s_release_version: stable # latest 'stable' release
k3s_release_version: testing # latest 'testing' release
k3s_release_version: v1.19 # latest 'v1.19' release
k3s_release_version: v1.19.3+k3s3 # specific release
# Specific commit
# CAUTION - only used for testing - must be 40 characters
k3s_release_version: 48ed47c4a3e420fa71c18b2ec97f13dc0659778bIf you are using the system-upgrade-controller you will need to use hard links rather than symbolic links as the controller will not be able to follow symbolic links. This option has been added however is not enabled by default to avoid breaking existing installations.
To enable the use of hard links, ensure k3s_install_hard_links is set
to true.
k3s_install_hard_links: trueThe result of this can be seen by running the following in k3s_install_dir:
ls -larthi | grep -E 'k3s|ctr|ctl' | grep -vE ".sh$" | sort
Symbolic Links:
[root@node1 bin]# ls -larthi | grep -E 'k3s|ctr|ctl' | grep -vE ".sh$" | sort
3277823 -rwxr-xr-x 1 root root 52M Jul 25 12:50 k3s-v1.18.4+k3s1
3279565 lrwxrwxrwx 1 root root 31 Jul 25 12:52 k3s -> /usr/local/bin/k3s-v1.18.6+k3s1
3279644 -rwxr-xr-x 1 root root 51M Jul 25 12:52 k3s-v1.18.6+k3s1
3280079 lrwxrwxrwx 1 root root 31 Jul 25 12:52 ctr -> /usr/local/bin/k3s-v1.18.6+k3s1
3280080 lrwxrwxrwx 1 root root 31 Jul 25 12:52 crictl -> /usr/local/bin/k3s-v1.18.6+k3s1
3280081 lrwxrwxrwx 1 root root 31 Jul 25 12:52 kubectl -> /usr/local/bin/k3s-v1.18.6+k3s1
Hard Links:
[root@node1 bin]# ls -larthi | grep -E 'k3s|ctr|ctl' | grep -vE ".sh$" | sort
3277823 -rwxr-xr-x 1 root root 52M Jul 25 12:50 k3s-v1.18.4+k3s1
3279644 -rwxr-xr-x 5 root root 51M Jul 25 12:52 crictl
3279644 -rwxr-xr-x 5 root root 51M Jul 25 12:52 ctr
3279644 -rwxr-xr-x 5 root root 51M Jul 25 12:52 k3s
3279644 -rwxr-xr-x 5 root root 51M Jul 25 12:52 k3s-v1.18.6+k3s1
3279644 -rwxr-xr-x 5 root root 51M Jul 25 12:52 kubectl
If you set k3s_build_cluster to false, this role will install each play
host as a standalone node. An example of when you might use this would be
when building a large number of standalone IoT devices running K3s. Below is a
hypothetical situation where we are to deploy 25 Raspberry Pi devices, each a
standalone system and not a cluster of 25 nodes. To do this we'd use a playbook
similar to the below:
- hosts: k3s_nodes # eg. 25 RPi's defined in our inventory.
vars:
k3s_build_cluster: false
roles:
- xanmanning.k3sBy default only one host will be defined as a control node by Ansible, If you do not set a host as a control node, this role will automatically delegate the first play host as a control node. This is not suitable for use within a Production workload.
If multiple hosts have k3s_control_node set to true, you must also set
datastore-endpoint in k3s_server as the connection string to a MySQL or
PostgreSQL database, or external Etcd cluster else the play will fail.
If using TLS, the CA, Certificate and Key need to already be available on the play hosts.
See: High Availability with an External DB
It is also possible, though not supported, to run a single K3s control node
with a datastore-endpoint defined. As this is not a typically supported
configuration you will need to set k3s_use_unsupported_config to true.
Since K3s v1.19.1 it is possible to use an embedded Etcd as the backend
database, and this is done by setting k3s_etcd_datastore to true.
The best practice for Etcd is to define at least 3 members to ensure quorum is
established. In addition to this, an odd number of members is recommended to
ensure a majority in the event of a network partition. If you want to use 2
members or an even number of members, please set k3s_use_unsupported_config
to true.
To deploy server manifests and server pod manifests from URL, you need to
specify a url and optionally a filename (if none provided basename is used). Below is an example of how to deploy the
Tigera operator for Calico and kube-vip.
---
k3s_server_manifests_urls:
- url: https://docs.projectcalico.org/archive/v3.19/manifests/tigera-operator.yaml
filename: tigera-operator.yaml
k3s_server_pod_manifests_urls:
- url: https://raw.githubusercontent.com/kube-vip/kube-vip/main/example/deploy/0.1.4.yaml
filename: kube-vip.yaml
When deploying k3s in an air gapped environment you should provide the k3s binary in ./files/. The binary will not be downloaded from Github and will subsequently not be verified using the provided sha256 sum, nor able to verify the version that you are running. All risks and burdens associated are assumed by the user in this scenario.
No dependencies on other roles.
Example playbook, single control node running testing channel k3s:
- hosts: k3s_nodes
vars:
k3s_release_version: testing
roles:
- role: xanmanning.k3sExample playbook, Highly Available with PostgreSQL database running the latest stable release:
- hosts: k3s_nodes
vars:
k3s_registration_address: loadbalancer # Typically a load balancer.
k3s_server:
datastore-endpoint: "postgres://postgres:verybadpass@database:5432/postgres?sslmode=disable"
pre_tasks:
- name: Set each node to be a control node
ansible.builtin.set_fact:
k3s_control_node: true
when: inventory_hostname in ['node2', 'node3']
roles:
- role: xanmanning.k3sContributions from the community are very welcome, but please read the contribution guidelines before doing so, this will help make things as streamlined as possible.
Also, please check out the awesome list of contributors.
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