mirror of
https://github.com/PyratLabs/ansible-role-k3s
synced 2024-12-12 14:00:18 +01:00
154 lines
5.7 KiB
Markdown
154 lines
5.7 KiB
Markdown
# Quickstart: K3s cluster with a HA control plane using embedded etcd
|
|
|
|
This is the quickstart guide to creating your own 3 node k3s cluster with a
|
|
highly available control plane using the embedded etcd datastore.
|
|
The control plane will all be workers as well.
|
|
|
|
:hand: This example requires your Ansible user to be able to connect to the
|
|
servers over SSH using key-based authentication. The user is also has an entry
|
|
in a sudoers file that allows privilege escalation without requiring a
|
|
password.
|
|
|
|
To test this is the case, run the following check replacing `<ansible_user>`
|
|
and `<server_name>`. The expected output is `Works`
|
|
|
|
`ssh <ansible_user>@<server_name> 'sudo cat /etc/shadow >/dev/null && echo "Works"'`
|
|
|
|
For example:
|
|
|
|
```text
|
|
[ xmanning@dreadfort:~/git/kubernetes-playground ] (master) $ ssh ansible@kube-0 'sudo cat /etc/shadow >/dev/null && echo "Works"'
|
|
Works
|
|
[ xmanning@dreadfort:~/git/kubernetes-playground ] (master) $
|
|
```
|
|
|
|
## Directory structure
|
|
|
|
Our working directory will have the following files:
|
|
|
|
```text
|
|
kubernetes-playground/
|
|
|_ inventory.yml
|
|
|_ ha_cluster.yml
|
|
```
|
|
|
|
## Inventory
|
|
|
|
Here's a YAML based example inventory for our servers called `inventory.yml`:
|
|
|
|
```yaml
|
|
---
|
|
|
|
# We're adding k3s_control_node to each host, this can be done in host_vars/
|
|
# or group_vars/ as well - but for simplicity we are setting it here.
|
|
k3s_cluster:
|
|
hosts:
|
|
kube-0:
|
|
ansible_user: ansible
|
|
ansible_host: 10.10.9.2
|
|
ansible_python_interpreter: /usr/bin/python3
|
|
k3s_control_node: true
|
|
kube-1:
|
|
ansible_user: ansible
|
|
ansible_host: 10.10.9.3
|
|
ansible_python_interpreter: /usr/bin/python3
|
|
k3s_control_node: true
|
|
kube-2:
|
|
ansible_user: ansible
|
|
ansible_host: 10.10.9.4
|
|
ansible_python_interpreter: /usr/bin/python3
|
|
k3s_control_node: true
|
|
|
|
```
|
|
|
|
We can test this works with `ansible -i inventory.yml -m ping all`, expected
|
|
result:
|
|
|
|
```text
|
|
kube-0 | SUCCESS => {
|
|
"changed": false,
|
|
"ping": "pong"
|
|
}
|
|
kube-1 | SUCCESS => {
|
|
"changed": false,
|
|
"ping": "pong"
|
|
}
|
|
kube-2 | SUCCESS => {
|
|
"changed": false,
|
|
"ping": "pong"
|
|
}
|
|
|
|
```
|
|
|
|
## Playbook
|
|
|
|
Here is our playbook for the k3s cluster (`ha_cluster.yml`):
|
|
|
|
```yaml
|
|
---
|
|
|
|
- name: Build a cluster with HA control plane
|
|
hosts: k3s_cluster
|
|
vars:
|
|
k3s_become_for_all: true
|
|
k3s_etcd_datastore: true
|
|
k3s_use_experimental: true # Note this is required for k3s < v1.19.5+k3s1
|
|
roles:
|
|
- role: xanmanning.k3s
|
|
```
|
|
|
|
## Execution
|
|
|
|
To execute the playbook against our inventory file, we will run the following
|
|
command:
|
|
|
|
`ansible-playbook -i inventory.yml ha_cluster.yml`
|
|
|
|
The output we can expect is similar to the below, with no failed or unreachable
|
|
nodes. The default behavior of this role is to delegate the first play host as
|
|
the primary control node, so kube-0 will have more changed tasks than others:
|
|
|
|
```text
|
|
PLAY RECAP *******************************************************************************************************
|
|
kube-0 : ok=53 changed=8 unreachable=0 failed=0 skipped=30 rescued=0 ignored=0
|
|
kube-1 : ok=47 changed=10 unreachable=0 failed=0 skipped=28 rescued=0 ignored=0
|
|
kube-2 : ok=47 changed=9 unreachable=0 failed=0 skipped=28 rescued=0 ignored=0
|
|
```
|
|
|
|
## Testing
|
|
|
|
After logging into any of the servers (it doesn't matter), we can test that k3s
|
|
is running across the cluster, that all nodes are ready and that everything is
|
|
ready to execute our Kubernetes workloads by running the following:
|
|
|
|
- `sudo kubectl get nodes -o wide`
|
|
- `sudo kubectl get pods -o wide --all-namespaces`
|
|
|
|
:hand: Note we are using `sudo` because we need to be root to access the
|
|
kube config for this node. This behavior can be changed with specifying
|
|
`write-kubeconfig-mode: 0644` in `k3s_server`.
|
|
|
|
**Get Nodes**:
|
|
|
|
```text
|
|
ansible@kube-0:~$ sudo kubectl get nodes -o wide
|
|
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
|
|
kube-0 Ready etcd,master 2m58s v1.19.4+k3s1 10.10.9.2 10.10.9.2 Ubuntu 20.04.1 LTS 5.4.0-56-generic containerd://1.4.1-k3s1
|
|
kube-1 Ready etcd,master 2m22s v1.19.4+k3s1 10.10.9.3 10.10.9.3 Ubuntu 20.04.1 LTS 5.4.0-56-generic containerd://1.4.1-k3s1
|
|
kube-2 Ready etcd,master 2m10s v1.19.4+k3s1 10.10.9.4 10.10.9.4 Ubuntu 20.04.1 LTS 5.4.0-56-generic containerd://1.4.1-k3s1
|
|
```
|
|
|
|
**Get Pods**:
|
|
|
|
```text
|
|
ansible@kube-0:~$ sudo kubectl get pods -o wide --all-namespaces
|
|
NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
|
|
kube-system coredns-66c464876b-rhgn6 1/1 Running 0 3m38s 10.42.0.2 kube-0 <none> <none>
|
|
kube-system helm-install-traefik-vwglv 0/1 Completed 0 3m39s 10.42.0.3 kube-0 <none> <none>
|
|
kube-system local-path-provisioner-7ff9579c6-d5xpb 1/1 Running 0 3m38s 10.42.0.5 kube-0 <none> <none>
|
|
kube-system metrics-server-7b4f8b595-nhbt8 1/1 Running 0 3m38s 10.42.0.4 kube-0 <none> <none>
|
|
kube-system svclb-traefik-9lzcq 2/2 Running 0 2m56s 10.42.1.2 kube-1 <none> <none>
|
|
kube-system svclb-traefik-vq487 2/2 Running 0 2m45s 10.42.2.2 kube-2 <none> <none>
|
|
kube-system svclb-traefik-wkwkk 2/2 Running 0 3m1s 10.42.0.7 kube-0 <none> <none>
|
|
kube-system traefik-5dd496474-lw6x8 1/1 Running 0 3m1s 10.42.0.6 kube-0 <none> <none>
|
|
```
|