131 lines
4.3 KiB
Markdown
131 lines
4.3 KiB
Markdown
# Build a Kubernetes cluster using K3s via Ansible
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Author: <https://github.com/itwars>
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Current Maintainer: <https://github.com/dereknola>
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Easily bring up a cluster on machines running:
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- [X] Debian
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- [X] Ubuntu
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- [X] Raspberry Pi OS
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- [X] RHEL Family (CentOS, Redhat, Rocky Linux...)
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- [X] SUSE Family (SLES, OpenSUSE Leap, Tumbleweed...)
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- [X] ArchLinux
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on processor architectures:
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- [X] x64
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- [X] arm64
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- [X] armhf
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## System requirements
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The control node **must** have Ansible 8.0+ (ansible-core 2.15+)
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All managed nodes in inventory must have:
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- Passwordless SSH access
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- Root access (or a user with equivalent permissions)
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It is also recommended that all managed nodes disable firewalls and swap. See [K3s Requirements](https://docs.k3s.io/installation/requirements) for more information.
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## Usage
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First copy the sample inventory to `inventory.yml`.
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```bash
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cp inventory-sample.yml inventory.yml
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```
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Second edit the inventory file to match your cluster setup. For example:
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```bash
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k3s_cluster:
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children:
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server:
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hosts:
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192.16.35.11:
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agent:
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hosts:
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192.16.35.12:
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192.16.35.13:
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```
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If needed, you can also edit `vars` section at the bottom to match your environment.
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If multiple hosts are in the server group the playbook will automatically setup k3s in HA mode with embedded etcd.
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An odd number of server nodes is required (3,5,7). Read the [official documentation](https://docs.k3s.io/datastore/ha-embedded) for more information.
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Setting up a loadbalancer or VIP beforehand to use as the API endpoint is possible but not covered here.
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Start provisioning of the cluster using the following command:
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```bash
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ansible-playbook playbook/site.yml -i inventory.yml
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```
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## Upgrading
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A playbook is provided to upgrade K3s on all nodes in the cluster. To use it, update `k3s_version` with the desired version in `inventory.yml` and run:
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```bash
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ansible-playbook playbook/upgrade.yml -i inventory.yml
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```
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## Airgap Install
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Airgap installation is supported via the `airgap_dir` variable. This variable should be set to the path of a directory containing the K3s binary and images. The release artifacts can be downloaded from the [K3s Releases](https://github.com/k3s-io/k3s/releases). You must download the appropriate images for you architecture (any of the compression formats will work).
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An example folder for an x86_64 cluster:
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```bash
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$ ls ./playbook/my-airgap/
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total 248M
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-rwxr-xr-x 1 $USER $USER 58M Nov 14 11:28 k3s
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-rw-r--r-- 1 $USER $USER 190M Nov 14 11:30 k3s-airgap-images-amd64.tar.gz
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$ cat inventory.yml
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...
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airgap_dir: ./my-airgap # Paths are relative to the playbook directory
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```
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Additionally, if deploying on a OS with SELinux, you will also need to download the latest [k3s-selinux RPM](https://github.com/k3s-io/k3s-selinux/releases/latest) and place it in the airgap folder.
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It is assumed that the control node has access to the internet. The playbook will automatically download the k3s install script on the control node, and then distribute all three artifacts to the managed nodes.
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## Kubeconfig
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After successful bringup, the kubeconfig of the cluster is copied to the control node and merged with `~/.kube/config` under the `k3s-ansible` context.
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Assuming you have [kubectl](https://kubernetes.io/docs/tasks/tools/#kubectl) installed, you can confirm access to your **Kubernetes** cluster with the following:
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```bash
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kubectl config use-context k3s-ansible
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kubectl get nodes
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```
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If you wish for your kubeconfig to be copied elsewhere and not merged, you can set the `kubeconfig` variable in `inventory.yml` to the desired path.
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## Local Testing
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A Vagrantfile is provided that provision a 5 nodes cluster using Vagrant (LibVirt or Virtualbox as provider). To use it:
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```bash
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vagrant up
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```
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By default, each node is given 2 cores and 2GB of RAM and runs Ubuntu 20.04. You can customize these settings by editing the `Vagrantfile`.
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## Need More Features?
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This project is intended to provide a "vanilla" K3s install. If you need more features, such as:
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- Private Registry
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- Advanced Storage (Longhorn, Ceph, etc)
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- External Database
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- External Load Balancer or VIP
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- Alternative CNIs
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See these other projects:
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- https://github.com/PyratLabs/ansible-role-k3s
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- https://github.com/techno-tim/k3s-ansible
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- https://github.com/jon-stumpf/k3s-ansible
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- https://github.com/alexellis/k3sup
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