Create a Kubernetes Cluster using Ansible and k0s.
This script is largely based on the extensive and outstanding work of the contributors of k3s-ansible and, of course, kubespray. I put it together to learn about Ansible and the new single binary and vanilla upstream Kubernetes distro k0s.
site.yml:
$ ansible-playbook site.yml -i inventory/multipass/inventory.ymlInstall k0s on worker and controller host in your inventory. Currently creates one Kubernetes control plane server.
reset.yml:
$ ansible-playbook reset.yml -i inventory/multipass/inventory.ymlDeletes k0s all its files, directories and services from all hosts.
For the quick creation of virtual machines, I have added a script that provisions a bunch of nodes via multipass and another small Python script that generates an Ansible inventory from the created instances.
Steps:
Create 5 instances with multipass and import your ssh public key with cloud-init (create_instances.sh):
$ ./tools/multipass_create_instances.sh
Create cloud-init to import ssh key...
[1/5] Creating instance k0s-1 with multipass...
Launched: k0s-1
[2/5] Creating instance k0s-2 with multipass...
Launched: k0s-2
[3/5] Creating instance k0s-3 with multipass...
Launched: k0s-3
[4/5] Creating instance k0s-4 with multipass...
Launched: k0s-4
[5/5] Creating instance k0s-5 with multipass...
Launched: k0s-5
Name State IPv4 Image
k0s-1 Running 192.168.64.32 Ubuntu 20.04 LTS
k0s-2 Running 192.168.64.33 Ubuntu 20.04 LTS
k0s-3 Running 192.168.64.56 Ubuntu 20.04 LTS
k0s-4 Running 192.168.64.57 Ubuntu 20.04 LTS
k0s-5 Running 192.168.64.58 Ubuntu 20.04 LTSGenerate your Ansible inventory:
$ cp -rfp inventory/sample inventory/multipass
$ ./tools/multipass_generate_inventory.py
Designate first instance as control plane
Created Ansible Inventory at: /Users/moritz/dev/k0s-ansible/tools/inventory.yml
$ cp tools/inventory.yml inventory/multipass/inventory.ymlTest the ssh connection to all instances in your inventory.yml:
$ ansible -i inventory/multipass/inventory.yml -m ping all
k0s-4 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}
k0s-1 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}
k0s-3 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}
k0s-2 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}
k0s-5 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}Create your cluster:
$ ansible-playbook site.yml -i inventory/multipass/inventory.yml
...
TASK [k0s/controller : print kubeconfig command] ****************************************************************************************************************
Friday 18 December 2020 18:05:36 +0100 (0:00:00.256) 0:01:57.277 *******
ok: [k0s-1] => {
"msg": "To use Cluster: export KUBECONFIG=/Users/moritz/dev/k0s-ansible/inventory/multipass/artifacts/k0s-kubeconfig.yml"
}
...
PLAY RECAP ******************************************************************************************************************************************************
k0s-1 : ok=18 changed=12 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
k0s-2 : ok=9 changed=6 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
k0s-3 : ok=9 changed=6 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
k0s-4 : ok=9 changed=6 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
k0s-5 : ok=9 changed=6 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
Friday 18 December 2020 18:05:39 +0100 (0:00:00.990) 0:02:00.104 *******
===============================================================================
download : Download k0s binary amd64 -------------------------------------------------------------------------------------------------------------------- 99.68s
k0s/controller : Wait for k8s apiserver ------------------------------------------------------------------------------------------------------------------ 7.38s
k0s/controller : Create join worker token ---------------------------------------------------------------------------------------------------------------- 3.35s
Gathering Facts ------------------------------------------------------------------------------------------------------------------------------------------ 2.18s
Gathering Facts ------------------------------------------------------------------------------------------------------------------------------------------ 1.06s
k0s/worker : Enable and check k0s service ---------------------------------------------------------------------------------------------------------------- 0.99s
k0s/controller : Enable and check k0s service ------------------------------------------------------------------------------------------------------------ 0.93s
Gathering Facts ------------------------------------------------------------------------------------------------------------------------------------------ 0.68s
k0s/controller : Write the k0s config file --------------------------------------------------------------------------------------------------------------- 0.61s
k0s/worker : Copy k0s service file ----------------------------------------------------------------------------------------------------------------------- 0.47s
prereq : Create a Directory "/etc/k0s" ------------------------------------------------------------------------------------------------------------------- 0.41s
k0s/controller : Copy k0s service file ------------------------------------------------------------------------------------------------------------------- 0.38s
k0s/controller : Set controller IP in kubeconfig --------------------------------------------------------------------------------------------------------- 0.34s
prereq : Create a Directory "/usr/libexec/k0s/" ---------------------------------------------------------------------------------------------------------- 0.30s
prereq : Create a Directory "/var/lib/k0s" --------------------------------------------------------------------------------------------------------------- 0.29s
k0s/worker : Create a Directory "/var/lib/k0s" ----------------------------------------------------------------------------------------------------------- 0.27s
k0s/controller : Copy kubectl binary to ansible host ----------------------------------------------------------------------------------------------------- 0.26s
k0s/controller : Copy config file to user home directory ------------------------------------------------------------------------------------------------- 0.22s
download : Download k0s binary arm64 --------------------------------------------------------------------------------------------------------------------- 0.11s
k0s/controller : print token ----------------------------------------------------------------------------------------------------------------------------- 0.03sConnect to your new Kubernetes cluster. The config is ready to use in the inventory/artifacts directory:
$ export KUBECONFIG=/Users/moritz/k0s-ansible/inventory/multipass/artifacts/k0s-kubeconfig.yml
$ kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k0s-2 Ready <none> 2m42s v1.19.4 192.168.64.33 <none> Ubuntu 20.04.1 LTS 5.4.0-54-generic containerd://1.4.3
k0s-3 Ready <none> 2m42s v1.19.4 192.168.64.56 <none> Ubuntu 20.04.1 LTS 5.4.0-54-generic containerd://1.4.3
k0s-4 Ready <none> 2m42s v1.19.4 192.168.64.57 <none> Ubuntu 20.04.1 LTS 5.4.0-54-generic containerd://1.4.3
k0s-5 Ready <none> 2m42s v1.19.4 192.168.64.58 <none> Ubuntu 20.04.1 LTS 5.4.0-54-generic containerd://1.4.3
$ kubectl run hello-k0s --image=quay.io/prometheus/busybox --rm -it --restart=Never --command -- sh -c "echo hello k0s"
hello k0s
pod "hello-k0s" deleted$ multipass delete $(multipass list --format csv | grep 'k0s' | cut -d',' -f1)
$ multipass purge