** Missing Kubernetes steps
   - Note taken on [2023-11-21 Tue 14:38] \\
     On the new ec2 server Kubernetes (kubeadm init) was not
     running. The error messages indicated the following steps to fix
     the situation:
   1. modprobe br_netfilter
   2. sudo su -c 'br_netfilter' >> /etc/modules.load.d/k8s.conf
   3. sudo su -c 'echo 1 > /proc/sys/net/ipv4/ip_forward'
   4. cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
       net.bridge.bridge-nf-call-ip6tables = 1
       net.bridge.bridge-nf-call-iptables = 1
       EOF
   5. sudo sysctl --system

** Jenkins on k8s
*** Setup Jenkins
    1. mkdir -p /var/jenkins/mnt; cd /var/jenkins
    2. mkdir k8s_config; cd k8s_config
    3. tar czf jenkins_k8s_v0.1.tar.gz
    4. kubectl create namespace devops-tools
    5. kubectl apply -f serviceAccount.yaml
    6. kubectl apply -f storage-class.yaml
    7. kubectl apply -f pvc.yaml
    8. Modify volume.yaml to change the hostname value (replace
       `ip-172-31-9-32.ap-south-1.compute.internal`) to the output
       of: `hostname -f`.
    9. kubectl apply -f volume.yaml
    10. kubectl apply -f deployment.yaml
    11. kubectl apply -f service.yaml
    12. Find out the Jenkins pod name:
        - kubectl get pod -n devops-tools | grep 'jenkins-'
    13. Admin password:
        - kubectl exec -it -n devops-tools <Jenkins Pod Name> cat /var/jenkins_home/secrets/initialAdminPassword
    14. Download CLI:
        curl localhost:32000/jnlpJars/jenkins-cli.jar > jenkins-cli.jar
    15. yum install java-11-openjdk.x86_64
    16. echo 'admin:<password>' > /var/jenkins/.jenkins_cli
    17. Status check:
        java -jar jenkins-cli.jar -s http://localhost:32000 -auth @/var/jenkins/.jenkins_cli version
    18. Plugins, replace "PluginName" with the plugin names below, one by one.
        * java -jar jenkins-cli.jar -s http://localhost:32000 -auth @/var/jenkins/.jenkins_cli install-plugin "<PluginName>" -deploy
        * Plugin list:
          1. dashboard-view
          2. credentials
          3. workflow-scm-step
          4. git-client
          5. git
          6. workflow-basic-steps
          7. pipeline-build-step
          8. workflow-aggregator
          9. timestamper
          10. build-timeout
          11. kubernetes
    19. Open http://localhost:32000/configure
        - Manage Jenkins -> System -> Uncheck "Usage Statistics"
    20. Open http://localhost:32000/configureSecurity and set "Agents:TCP port for JNLP agents" to "random"

*** Setup Kubernetes Cloud
    1. Open Jenkins in browser.
    2. Open http://localhost:32000/manage/cloud/ -> New cloud
    3. Enter Cloud name: "k8sLocal", Type: "Kubernetes" -> Create
    4. Kubernetes cloud details, only fill the following details:
       - Kubernetes URL: 172.31.9.32:6443 (local IP of machine, run: `ip addr show`)
       - Kubernetes Namespace: devops-tools
       - Jenkins URL: 10.103.162.93:8080 (run: `kubectl get service -n devops-tools jenkins-service`)
       - Check "Web Socket Connection"
    5. Click on "Save"
    6. Click on "k8sLocal" -> Click on "Pod Templates" -> Create new
    7. Pod template settings:
       - Name: jenkins-slave
       - Kubernetes URL: 172.31.9.32:6443 (local IP of machine)
       - Namespace: devops-tools
       - Labels: jenkins-slave
       - Usage: "Use this node as much as possible"
       - Containers -> "Add template"
         - Name: jenkins-slave
         - Docker image: jenkins/inbound-agent
         - Working directory: /home/jenkins
         - Command to run: /bin/sh -c
         - Arguments to pass to the command: cat
       - Service Account: jenkins-admin
       - Pod retention: Never
       - Workspace volume: Empty dir workspace

*** Create project on Jenkins
    1. New item -> Select "Pipeline", Name: "PipelineProject"
    2. Check "Do not allow concurrent builds"
    3. Build Triggers:
       - Poll SCM:
         - Schedule: "H/5 * * * *"
    4. Modify pipeline.groovy to change values as needed and save the
       file.
    5. Now copy-paste pipeline.groovy in "Pipeline Definition"
       section.