15 May 2021

Launching Kubernetes Cluster using Ansible on AWS

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What is Kubernetes ?

Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available.

Why you need Kubernetes and what it can do ?

Containers are a good way to bundle and run your applications. In a production environment, you need to manage the containers that run the applications and ensure that there is no downtime. For example, if a container goes down, another container needs to start. Wouldn’t it be easier if this behavior was handled by a system? That’s how Kubernetes comes to the rescue! Kubernetes provides you with a framework to run distributed systems resiliently. It takes care of scaling and failover for your application, provides deployment patterns, and more. For example, Kubernetes can easily manage a canary deployment for your system.

Kubernetes provides you with:

What is Ansible?

Ansible is a configuration management system written in Python using a declarative markup language to describe configurations. It is used to automate software configuration and deployment.

Ansible Architecture :

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Ansible Playbooks :

Ordered lists of tasks, saved so you can run those tasks in that order repeatedly. Playbooks can include variables as well as tasks. Playbooks are written in YAML and are easy to read, write, share and understand.

Inventory :

A list of managed nodes. An inventory file is also sometimes called a “hostfile”. Your inventory can specify information like IP address for each managed node. An inventory can also organize managed nodes.

Let’s Begin…

We don’t have any hosts or instances running ak-2

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Launching EC2 Instances using Ansible with dynamic inventory :

ansible-galaxy init ec2
ec2:
         key_name: "{{ key_name }}"
         instance_type: "{{ instance_type }}"
         image: "{{ image_id }}"
         wait: yes
         count: "{{ count }}"
         #         instance_tags:
         #       name: "sample_os"
         vpc_subnet_id: "{{ subnet_id }}"
         assign_public_ip: yes
         state: present
         region: "{{ region }}"
         group_id: "{{ sg_group_id }}"
         aws_access_key: "{{ aws_access_key }}"
         aws_secret_key: "{{ aws_secret_key }}"
         instance_tags:
             Name: "{{ item }}"
  loop: "{{ OS_name }}"
aws_secret_key: "aws_secret_key"
key_name: "testing"
image_id: "ami-038f1ca1bd58a5790"
count: 1
subnet_id: "subnet-52bc140d"
region: "us-east-1"
sg_group_id: "sg-0639b0dd0a69545ea"
instance_type: "t2.micro"
OS_name:
     - "K8S_Master"
     - "K8S_Node1"
     - "K8S_Node2"
>>> In playbook setup.yml :
- hosts: localhost
  gather_facts: False
  #vars_files: secret.yml
  roles:
  - name: "EC2 Launch"
    role: /root/task23/k8s/ec2/
ansible-playbook setup.yml

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Setting Up Master Node and Worker Nodes

In Master Node,

ansible-galaxy init k8s_master
- name: "Creating Repo for Kubernetes"
  copy:
          src: kubernetes.repo
          dest: /etc/yum.repos.d/kubernetes.repo
- name: "Installing Software"
  package:
          name: "{{ item }}"
          state: present
  loop: "{{ package_name }}"
- name: "Starting services"
  service:
          name:  "{{ item }}"
          state: started
  loop: "{{ package }}"
- name: "Changing driver to systemd"
  copy:
          src: daemon.json
          dest: /etc/docker/daemon.json
- name: "Restart Docker Services"
  service:
          name: docker
          state: restarted
- name: "Pulling Images"
  shell: kubeadm config images pull
- name: "Bridge to 1"
  shell: echo "1" > /proc/sys/net/bridge/bridge-nf-call-iptables
- name: "kubeadm init"
  shell: kubeadm init --pod-network-cidr=10.244.0.0/16 --ignore-preflight-errors=NumCPU --ignore-preflight-errors=Mem
  ignore_errors: yes
- name: "Creating .kube directory"
  file:
    path: $HOME/.kube
    state: directory
- name: "Copying file"
  shell: cp  -i  /etc/kubernetes/admin.conf  $HOME/.kube/config
- name: "Changing Owner Permissions"
  shell: chown $(id -u):$(id -g) $HOME/.kube/config
- name: "Setting up Flannel"
  shell: kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
  changed_when: False
- name: "Token Creation"
  shell: kubeadm  token create --print-join-command
  register: token
- name: "Printing Token"
  debug:
         var: token.stdout
package_name:
        - "docker"
        - "kubelet"
        - "kubeadm"
        - "kubectl"
        - "iproute-tc"
package:
        - "docker"
        - "kubelet"

In Worker Nodes,

ansible-galaxy init k8s_nodes
- name: "Creating Repo for Kubernetes"
  copy:
          src: kubernetes.repo
          dest: /etc/yum.repos.d/kubernetes.repo
- name: "Installing Software"
  package:
          name: "{{ item }}"
          state: present
  loop: "{{ package_name }}"
- name: "Starting services"
  service:
          name:  "{{ item }}"
          state: started
  loop: "{{ package }}"
- name: "Changing driver to systemd"
  copy:
          src: daemon.json
          dest: /etc/docker/daemon.json
- name: "Restart Docker Services"
  service:
          name: docker
          state: restarted
- name: "Bridge to 1"
  shell: echo "1" > /proc/sys/net/bridge/bridge-nf-call-iptables
- name: "Using token"
  shell: "{{ token }}"
>>> In vars file :
package_name:
        - "docker"
        - "kubelet"
        - "kubeadm"
        - "kubectl"
        - "iproute-tc"
package:
        - "docker"
        - "kubelet"
- hosts: "tag_Name_K8S_Master"
  roles:
  - name: "K8S Master"
    role: /root/k8s/k8s_master
- hosts: ["tag_Name_K8S_Node1", "tag_Name_K8S_Node2"]
  vars_prompt:
    - name: token
      prompt: "Enter token :"
      private: no
  roles:
  - name: "K8S_Nodes"
    role: /root/k8s/k8s_nodes
ansible-playbook k8s_setup.yml

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kubectl get nodes

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http://<master_ip>:<port_no>

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You can reach out to me on linkedin / mail to discuss more!