Ansible role for installing Rancher Labs k3s ("Lightweight Kubernetes") as either a standalone server or cluster.
The control host requires the following Python dependencies:
jmespath >= 0.9.0
This role has been tested on Ansible 2.7.0+ against the following Linux Distributions:
- Amazon Linux 2
- CentOS 8
- CentOS 7
- Debian 9
- Debian 10
- Fedora 29
- Fedora 30
- Fedora 31
- openSUSE Leap 15
- Ubuntu 18.04 LTS
Rancher Labs is awesome and has released k3s as v1.0.0, however at the time of creating this role I do not have a k3s cluster in production nor am I unlikely to ever have one. Please ensure you practice extreme caution and operational rigor before using this role for any serious workloads.
If you have any problems please create a GitHub issue, I maintain this role in my spare time so I cannot promise a speedy fix delivery.
Below are variables that are set against all of the play hosts for environment consistency.
Variable | Description | Default Value |
---|---|---|
k3s_cluster_state |
State of cluster: installed, started, stopped, restarted, downloaded, uninstalled. | installed |
k3s_release_version |
Use a specific version of k3s, eg. v0.2.0 . Specify false for stable. |
false |
k3s_build_cluster |
When multiple play_hosts are available, attempt to cluster. Read notes below. |
true |
k3s_github_url |
Set the GitHub URL to install k3s from. | https://github.com/rancher/k3s |
k3s_install_dir |
Installation directory for k3s. | /usr/local/bin |
k3s_server_manifests_dir |
Path for place the k3s_server_manifests_templates . |
/var/lib/rancher/k3s/server/manifests |
k3s_server_manifests_templates |
A list of Auto-Deploying Manifests Templates. | [] |
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_non_root |
Install k3s as non-root user. See notes below. | false |
k3s_control_workers |
Are control hosts also workers? | true |
k3s_cluster_cidr |
Network CIDR to use for pod IPs | 10.42.0.0/16 |
k3s_service_cidr |
Network CIDR to use for service IPs | 10.43.0.0/16 |
k3s_control_node_address |
Use a specific control node address. IP or FQDN. | NULL |
k3s_control_token |
Use a specific control token, please read notes below. | NULL |
k3s_https_port |
HTTPS port listening port. | 6443 |
k3s_use_docker |
Use Docker rather than Containerd? | false |
k3s_no_flannel |
Do not use Flannel | false |
k3s_flannel_backend |
Flannel backend ('none', 'vxlan', 'ipsec', 'host-gw' or 'wireguard') | vxlan |
k3s_no_coredns |
Do not use CoreDNS | false |
k3s_cluster_dns |
Cluster IP for CoreDNS service. Should be in your service-cidr range. | NULL |
k3s_cluster_domain |
Cluster Domain. | cluster.local |
k3s_resolv_conf |
Kubelet resolv.conf file | NULL |
k3s_no_traefik |
Do not use Traefik | false |
k3s_no_servicelb |
Do not use ServiceLB, necessary for using something like MetalLB. | false |
k3s_no_local_storage |
Do not use Local Storage | false |
k3s_default_local_storage_path |
Set Local Storage Path. Specify false for default. |
false |
k3s_no_metrics_server |
Do not deploy metrics server | false |
k3s_disable_scheduler |
Disable Kubernetes default scheduler | false |
k3s_disable_cloud_controller |
Disable k3s default cloud controller manager. | false |
k3s_disable_network_policy |
Disable k3s default network policy controller. | false |
k3s_write_kubeconfig_mode |
Define the file mode from the generated KubeConfig, eg. 644 |
NULL |
k3s_datastore_endpoint |
Define the database or etcd cluster endpoint for HA. | NULL |
k3s_datastore_cafile |
Define the database TLS CA file. | NULL |
k3s_datastore_certfile |
Define the database TLS Cert file. | NULL |
k3s_datastore_keyfile |
Define the database TLS Key file. | NULL |
k3s_become_for_all |
Enable become for all (where value for k3s_become_for_* is NULL |
false |
k3s_become_for_systemd |
Enable become for systemd commands. | NULL |
k3s_become_for_install_dir |
Enable become for writing to k3s_install_dir . |
NULL |
k3s_become_for_usr_local_bin |
Enable become for writing to /usr/local/bin/ . |
NULL |
k3s_become_for_package_install |
Enable become for installing prerequisite packages. | NULL |
k3s_become_for_kubectl |
Enable become for kubectl commands. | NULL |
k3s_become_for_uninstall |
Enable become for running uninstall scripts. | NULL |
k3s_dqlite_datastore |
Use DQLite as the database backend for HA. (EXPERIMENTAL) | false |
k3s_secrets_encryption |
Use secrets encryption at rest. (EXPERIMENTAL) | false |
If 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: v1.16.9+k3s1
It 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: v1.18 # latest v1.18 release
k3s_release_version: v1.17-testing # latest v1.17 testing release
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 be building a large
number of IoT devices running K3s. Below is a hypothetical situation where we
are to deploy 25 Rasberry 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.k3s
To install k3s as non root you must not use become: true
. The intention of
this variable is to run a single node development environment. At the time
of release v1.0.1, rootless is still experimental.
You must also ensure that you set both k3s_use_experimental
and k3s_use_unsupported_config
to true
.
Additionally k3s_install_dir
must be writable by your user.
If you set this, you are explicitly specifying the control host that agents should connect to, the value should be an IP address or FQDN.
If the control host is not configured by this role, then you need to also
specify the k3s_control_token
.
Please note that this may potentially break setting up agents.
Below are variables that are set against specific hosts in your inventory.
Variable | Description | Default Value |
---|---|---|
k3s_control_node |
Define the host as a control plane node, (True/False). | false |
k3s_node_name |
Define the name of this node. | $(hostname) |
k3s_node_id |
Define the ID of this node. | NULL |
k3s_flannel_interface |
Define the flannel proxy interface for this node. | NULL |
k3s_bind_address |
Define the bind address for this node. | localhost |
k3s_node_ip_address |
IP Address to advertise for this node. | NULL |
k3s_node_external_address |
External IP Address to advertise for this node. | NULL |
k3s_node_labels |
List of node labels. | NULL |
k3s_kubelet_args |
A list of kubelet args to pass to the server. | [] |
k3s_node_taints |
List of node taints. | NULL |
k3s_node_data_dir |
Folder to hold state. | /var/lib/rancher/k3s |
k3s_tls_san |
Add additional hosname or IP as Subject Alternate Name in the TLS cert. | NULL |
By 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 (master). This is not suitable for use in a Production workload.
If multiple hosts have k3s_control_node
set to true, you must also set
k3s_datastore_endpoint
as the connection string to a MySQL or PostgreSQL
database, or 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 master with a
k3s_datastore_endpoint
defined. As this is not a typically supported
configuration you will need to set k3s_use_unsupported_config
to true
.
Since K3s v1.0.0 it is possible to use DQLite as the backend database, and this
is done by setting k3s_dqlite_datastore
to true. As this is an experimental
feature you will also need to set k3s_use_experimental
to true.
If you are running k3s on systems with multiple network interfaces, it is necessary to have the flannel interface on a network interface that is routable to the master node(s).
This parameter allows for assigning additional kubelet args to the server during runtime. For instance, to use the Azure Cloud Controller, assign the following to the master node's configuration in your host file.
Note, when using an external cloud controller as below, ensure that the native k3s
cloud controller is disabled by setting the k3s_disable_cloud_controller
to true
.
YAML:
k3s_kubelet_args:
- cloud-provider: external
- provider-id: azure
Both these variables are lists that will be iterated on. The below example will output the following:
YAML:
k3s_node_labels:
- foo: bar
- hello: world
k3s_node_taints:
- key1: value1:NoExecute
ARGS:
--node-label foo=bar \
--node-label hello=world \
--node-taint key1=value1:NoExecute
No dependencies on other roles.
Example playbook, single master node running v0.10.2:
- hosts: k3s_nodes
roles:
- { role: xanmanning.k3s, k3s_release_version: v0.10.2 }
Example playbook, Highly Available running the latest release:
- hosts: k3s_nodes
vars:
molecule_is_test: true
k3s_control_node_address: loadbalancer
k3s_datastore_endpoint: "postgres://postgres:verybadpass@database:5432/postgres?sslmode=disable"
pre_tasks:
- name: Set each node to be a control node
set_fact:
k3s_control_node: true
when: inventory_hostname in ['node2', 'node3']
roles:
- role: xanmanning.k3s