AWS - Install Kubernetes using Ansible
Quick note: the original post dates from 25-11-2019 but got updated at 01-04-2020 with latest Kubernetes version.
Introduction
This blog post is a follow up of a post we wrote couple of days ago where we created 3 EC2 instances on AWS. That blog post can be found here. If you want to follow along with this guide, then use that post to create 3 instances.
Executing the code from that post, will result in three EC2 instances on AWS:
The output of the Terraform script gives me back the following IP addresses to be used in our Ansible hosts file.
Outputs:
instance_ip_addr = [
"172.31.13.140",
"172.31.5.24",
"172.31.14.2",
]
instance_ips = [
"18.203.68.253",
"3.249.4.142",
"3.249.141.242",
]Note: ensure to select instance types with 2CPU’s or more (t2.medium as a minimim in AWS), otherwise you will get an error message later: > The number of available CPUs 1 is less than the required 2
Using Ansible to install Kubernetes
In this post, we will focus on using Ansible to install Kubernetes. We will base ourselves on an excellent post written by the DigitalOcean community but finetune it for our AWS endeavour. Also, what we do here with Ansible are essentially the same steps as I did in this post where I configured Kubernetes manually.
First of all, let’s create a hosts file for our Ansible scripts. We will define 1 master and 2 workers. The IP addresses are the same as the ones in the DigitalOcean screenshot (obviously).
#hosts
[masters]
master ansible_host=18.203.68.253 ansible_user=ubuntu
[workers]
worker1 ansible_host=3.249.4.142 ansible_user=ubuntu
worker2 ansible_host=3.249.141.242 ansible_user=ubuntu
[all:vars]
ansible_python_interpreter=/usr/bin/python3
ansible_ssh_private_key_file=~/.ssh/AWS-Cisco.pemNext, we will define create a file to install all the updates, to create the ubuntu user and ensure the ubuntu user has sudo rights.
- hosts: all
become: yes
tasks:
- name: create the 'ubuntu' user
user: name=ubuntu append=yes state=present createhome=yes shell=/bin/bash
- name: allow 'ubuntu' to have passwordless sudo
lineinfile:
dest: /etc/sudoers
line: 'ubuntu ALL=(ALL) NOPASSWD: ALL'
validate: 'visudo -cf %s'
- name: set up authorized keys for the ubuntu user
authorized_key: user=ubuntu key="{{item}}"
with_file:
- ~/.ssh/id_rsa.pubNext up, we will create a different file that installs the Kubernetes specific dependencies on the 3 nodes. First of all, we start with the installation of Docker, then we add Kubernetes as well as the kubelet and kubeadm toolset.
#kube-dependencies.yml
- hosts: all
become: yes
tasks:
- name: install Docker
apt:
name: docker.io
state: present
update_cache: true
- name: install APT Transport HTTPS
apt:
name: apt-transport-https
state: present
- name: add Kubernetes apt-key
apt_key:
url: https://packages.cloud.google.com/apt/doc/apt-key.gpg
state: present
- name: add Kubernetes' APT repository
apt_repository:
repo: deb http://apt.kubernetes.io/ kubernetes-xenial main
state: present
filename: 'kubernetes'
- name: install kubelet
apt:
name: kubelet
state: present
update_cache: true
- name: install kubeadm
apt:
name: kubeadm
state: present
- hosts: master
become: yes
tasks:
- name: install kubectl
apt:
name: kubectl
state: presentWhen the above is finished, we will create a specific file for the master node. This file will take care of the initialization of the Kubernetes cluster, will create the .kube directory and will copy the admin.conf file to the user’s kube.config file and also install the Calico network. Just similar as what we did in the manual process.
#master.yml
- hosts: master
become: yes
tasks:
- name: initialize the cluster
shell: kubeadm init --pod-network-cidr=10.244.0.0/16 >> cluster_initialized.txt
args:
chdir: $HOME
creates: cluster_initialized.txt
- name: create .kube directory
become: yes
become_user: ubuntu
file:
path: $HOME/.kube
state: directory
mode: 0755
- name: copy admin.conf to user's kube config
copy:
src: /etc/kubernetes/admin.conf
dest: /home/ubuntu/.kube/config
remote_src: yes
owner: ubuntu
- name: install Pod network
become: yes
become_user: ubuntu
shell: kubectl apply -f https://docs.projectcalico.org/v3.9/manifests/calico.yaml >> pod_network_setup.txt
args:
chdir: $HOME
creates: pod_network_setup.txtNote: if you prefer to use Flannel CNI plugin instead of Calico, it suffices to replace that part with:
- name: install Pod network
become: yes
become_user: ubuntu
shell: kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml >> pod_network_setup.txt
args:
chdir: $HOME
creates: pod_network_setup.txtLast file we create is the workers.yml file. In that file, we will first retrieve the join command from the master node and then we will join worker nodes to the cluster.
- hosts: master
become: yes
gather_facts: false
tasks:
- name: get join command
shell: kubeadm token create --print-join-command
register: join_command_raw
- name: set join command
set_fact:
join_command: "{{ join_command_raw.stdout_lines[0] }}"
- hosts: workers
become: yes
tasks:
- name: join cluster
shell: "{{ hostvars['master'].join_command }} >> node_joined.txt"
args:
chdir: $HOME
creates: node_joined.txtExecuting the Ansible playbooks
First, we will perform the initial configuration as described above.
WAUTERW-M-65P7:Ansible wauterw$ ansible-playbook -i hosts initial.yml
PLAY [all] ************************************************************************************************************************************
TASK [Gathering Facts] ************************************************************************************************************************
ok: [worker2]
ok: [master]
ok: [worker1]
TASK [create the 'ubuntu' user] ***************************************************************************************************************
ok: [master]
ok: [worker2]
ok: [worker1]
TASK [allow 'ubuntu' to have passwordless sudo] ***********************************************************************************************
changed: [worker1]
changed: [worker2]
changed: [master]
TASK [set up authorized keys for the ubuntu user] *********************************************************************************************
changed: [worker2] => (item=ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC6ULleEqtsN/OoaAmQbZCuHjNgDrRr3Gur33n6WfpuHCDNAiqTo5kr0jTKlhWPiBTtuokbONvyJGGL9qkpSmM5isr/fK88WpUOqEc28wYENHCQXsdRMZUYAdxPrtdQgAXSMJEHye9ea8e7E/U275c9D1kKNcHV/Xf06RNSqbHTFvbX79WqK3F6I6DG8rcogw+WGw0pH7lqg/8k1aWjH+apNXjl8NO3ABzLNyc3I6ytUvFOHIkRZeEPNuH4mpb122VAPTYiSpU+F6E8PQUomnGPSSMwfU+T0Sq33H4TwXkgRnuuhD/ZutJjb31mARluxU/nf2FlKuLKHuImc39opoMF wauterw@WAUTERW-M-65P7)
changed: [worker1] => (item=ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC6ULleEqtsN/OoaAmQbZCuHjNgDrRr3Gur33n6WfpuHCDNAiqTo5kr0jTKlhWPiBTtuokbONvyJGGL9qkpSmM5isr/fK88WpUOqEc28wYENHCQXsdRMZUYAdxPrtdQgAXSMJEHye9ea8e7E/U275c9D1kKNcHV/Xf06RNSqbHTFvbX79WqK3F6I6DG8rcogw+WGw0pH7lqg/8k1aWjH+apNXjl8NO3ABzLNyc3I6ytUvFOHIkRZeEPNuH4mpb122VAPTYiSpU+F6E8PQUomnGPSSMwfU+T0Sq33H4TwXkgRnuuhD/ZutJjb31mARluxU/nf2FlKuLKHuImc39opoMF wauterw@WAUTERW-M-65P7)
changed: [master] => (item=ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC6ULleEqtsN/OoaAmQbZCuHjNgDrRr3Gur33n6WfpuHCDNAiqTo5kr0jTKlhWPiBTtuokbONvyJGGL9qkpSmM5isr/fK88WpUOqEc28wYENHCQXsdRMZUYAdxPrtdQgAXSMJEHye9ea8e7E/U275c9D1kKNcHV/Xf06RNSqbHTFvbX79WqK3F6I6DG8rcogw+WGw0pH7lqg/8k1aWjH+apNXjl8NO3ABzLNyc3I6ytUvFOHIkRZeEPNuH4mpb122VAPTYiSpU+F6E8PQUomnGPSSMwfU+T0Sq33H4TwXkgRnuuhD/ZutJjb31mARluxU/nf2FlKuLKHuImc39opoMF wauterw@WAUTERW-M-65P7)
PLAY RECAP ************************************************************************************************************************************
master : ok=4 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker1 : ok=4 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker2 : ok=4 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
Next, we will install the Kubernetes dependencies:
WAUTERW-M-65P7:Ansible wauterw$ ansible-playbook -i hosts kube-dependencies.yml
PLAY [all] ************************************************************************************************************************************
TASK [Gathering Facts] ************************************************************************************************************************
ok: [worker1]
ok: [worker2]
ok: [master]
TASK [install Docker] *************************************************************************************************************************
[WARNING]: Could not find aptitude. Using apt-get instead
changed: [master]
changed: [worker2]
changed: [worker1]
TASK [install APT Transport HTTPS] ************************************************************************************************************
changed: [master]
changed: [worker2]
changed: [worker1]
TASK [add Kubernetes apt-key] *****************************************************************************************************************
changed: [worker2]
changed: [master]
changed: [worker1]
TASK [add Kubernetes' APT repository] *********************************************************************************************************
changed: [worker2]
changed: [worker1]
changed: [master]
TASK [install kubelet] ************************************************************************************************************************
changed: [worker2]
changed: [master]
changed: [worker1]
TASK [install kubeadm] ************************************************************************************************************************
changed: [worker1]
changed: [worker2]
changed: [master]
PLAY [master] *********************************************************************************************************************************
TASK [Gathering Facts] ************************************************************************************************************************
ok: [master]
TASK [install kubectl] ************************************************************************************************************************
ok: [master]
PLAY RECAP ************************************************************************************************************************************
master : ok=9 changed=6 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker1 : ok=7 changed=6 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker2 : ok=7 changed=6 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
When the dependencies are installed, it’s time to configure the master.
WAUTERW-M-65P7:Ansible wauterw$ ansible-playbook -i hosts master.yml
PLAY [master] *********************************************************************************************************************************
TASK [Gathering Facts] ************************************************************************************************************************
ok: [master]
TASK [initialize the cluster] *****************************************************************************************************************
changed: [master]
TASK [create .kube directory] *****************************************************************************************************************
changed: [master]
TASK [copy admin.conf to user's kube config] **************************************************************************************************
changed: [master]
TASK [install Pod network] ********************************************************************************************************************
changed: [master]
PLAY RECAP ************************************************************************************************************************************
master : ok=5 changed=4 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
Next up, we are going to configure the workers.
WAUTERW-M-65P7:Ansible wauterw$ ansible-playbook -i hosts workers.yml
PLAY [master] *********************************************************************************************************************************
TASK [get join command] ***********************************************************************************************************************
changed: [master]
TASK [set join command] ***********************************************************************************************************************
ok: [master]
PLAY [workers] ********************************************************************************************************************************
TASK [Gathering Facts] ************************************************************************************************************************
ok: [worker2]
ok: [worker1]
TASK [join cluster] ***************************************************************************************************************************
changed: [worker2]
changed: [worker1]
PLAY RECAP ************************************************************************************************************************************
master : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker1 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
worker2 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
Validate the K8S cluster
First, we need to SSH into the K8S master. In our case, this is available on ‘IP address’.
ssh ubuntu@18.203.68.253
This works, since we have configured the EC2 instances with our public key that is stored in our ~/.ssh directory (id_rsa,pub). Since we are also using our security key from AWS, we can also login as follows.
ssh -i AWS.pem ubuntu@18.203.68.253
Next, let’s see if our nodes are up:
ubuntu@ip-172-31-13-140:~$ kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
ip-172-31-13-140 Ready master 11m v1.18.0 172.31.13.140 <none> Ubuntu 18.04.1 LTS 4.15.0-1021-aws docker://19.3.6
ip-172-31-14-2 Ready <none> 4m29s v1.18.0 172.31.14.2 <none> Ubuntu 18.04.1 LTS 4.15.0-1021-aws docker://19.3.6
ip-172-31-5-24 Ready <none> 4m29s v1.18.0 172.31.5.24 <none> Ubuntu 18.04.1 LTS 4.15.0-1021-aws docker://19.3.6And our namespaces:
ubuntu@ip-172-31-13-140:~$ kubectl get namespaces
NAME STATUS AGE
default Active 12m
kube-node-lease Active 12m
kube-public Active 12m
kube-system Active 12mWe are now ready to deploy some applications onto our cluster. We’ll blog about that at some later point in time. First wanted to get my head around the installation of the K8S clusters onto several plartforms.
See you next time!