K8s system requirement configuration using Ansible

PART2:

pic credit: tenor.com

So far in part1 of the Infrastructure setup, we have manually worked on the configuration part of the ansible controller machine. Now we are going to automate by using ansible playbooks to accomplish the rest of Infra setup for K8s cluster installation. If you are looking to run one playbook for all the part 2 execution, please use playbook.

step1: change the hostname of all the k8s target machines.

$ # execute the below snippet in k8s workdir and execute the playbook

cat <<EOF> infra-prereq-part2.yaml

- name: "Infra pre-req setup part2"

  hosts: all

  become: yes

  tasks:

     - name: "change the hostname"

       lineinfile:

          regexp: '.*'

          line: "{{inventory_hostname}}"

          path: /etc/hostname  

EOF

$ ansible-playbook -i inventory infra-prereq-part2.yaml --ask-become-pass

BECOME pass: "enter your sudo pass here..."

Step2: Add the host entries to /etc/hosts file.

Here we are going to use the "template" module, so we will create the template folder under the current workdir.

$ mkdir templates

#  jinja2 Template format looks as below and ends with "j2" extension.

cat <<EOF> templates/hosts.j2

{% for host in groups['k8s'] %}

{{ hostvars[host]['ansible_host'] }}   {{hostvars[host].inventory_hostname}}

{% endfor %}

EOF

$ # execute the below snippet and run the playbook to add the host entries in all the targets.

cat <<EOF> hosts_file.yaml

- name: hosts file change

  become: yes

  hosts: all

  tasks:

     - name: "hosts entry"

       template:

           src: hosts.j2

           dest: /etc/hosts

           backup: yes

     - name: "Add default values back"

       blockinfile:

               insertbefore: BOF

               marker: " "

               block: |

                  127.0.0.1   localhost controller

                  ::1         localhost controller

               path: /etc/hosts

EOF   

$ ansible-playbook -i inventory hosts_file.yaml --ask-become-pass

prompt: BECOME pass: "enter your sudo pass here..."

Step3: Final System pre-requisites that need to be addressed before the CRI and K8s install.

$ # Execute the below snippet and apply the playbook for final results.

cat <<EOF> system-final-prereq.yaml

- name: Final system pre-req's

  hosts: all

  become: yes

  tasks:

   - name: disable firewall service

     service:

        name: firewalld

        state: stopped

        enabled: false

   - name: Disable SWAP

     shell: |

       swapoff -a

   - name: Disable SWAP in fstab

     lineinfile:

       path: /etc/fstab

       regexp: 'swap'

       state: absent

   - name: disable SELinux

     command: setenforce 0

     ignore_errors: yes

   - name: disable SELinux on reboot

     selinux:

       state: disabled

   - name: Letting iptables see bridged traffic

     shell: cat <<EOF | sudo tee  /etc/sysctl.d/k8s.conf \

                      net.bridge.bridge-nf-call-ip6tables = 1 \

                      net.bridge.bridge-nf-call-iptables = 1 \

                      EOF

   - name: apply the iptables changes

     shell: sysctl --system

   - name: Add the Yum reposiory to Database

     yum_repository:

        name: Kubernetes

        description: K8s YUM repository

        baseurl: https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64

        gpgkey: https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

        gpgcheck: yes

        repo_gpgcheck: yes

        enabled: yes

   - name: Reboot the targets after the swap and selinux

     reboot:

EOF

$  ansible-playbook -i inventory system_prereq.yaml --ask-become-pass 

Successfully, we have completed the system pre-requisites and we can now move to Container Runtime, LB setup, and K8s master-slave setup.

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