JenkinsAutomation

Jenkins server starts from cmd.exe with help of python subprocess

• StartJenkinsServer (from cmd.exe and REST API verification)
• SubprocessUtility (common user)

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Jenkins Installation Guide with Java Setup

This guide explains how to download and install Jenkins, configure Java (JDK 21), and set up the environment variables for Java.

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1. Download and Install Java (JDK 21)

Step-1: Download Java 21

• Visit the official Oracle JDK 21 download page:
  • Java 21 x64 .exe Installer
  • Java 21 x64 .msi Installer
• Choose either .exe or .msi depending on your preference (for most users, .exe is recommended).

Step-2: Install Java

• Run the downloaded installer and follow the instructions to install Java.
• By default, it will be installed in C:\Program Files\Java\jdk-21.

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2. Set Up Java Environment Variables

Step-1: Set JAVA_HOME

• Right-click on This PC or My Computer and select Properties.
• Click Advanced system settings → Environment Variables.
• Under System Variables, click New.
  • Variable name: JAVA_HOME
  • Variable value: C:\Program Files\Java\jdk-21
• Click OK.

Step-2: Add Java to Path

• In the same Environment Variables window, under System Variables, scroll down and find Path.

• Select Path and click Edit.

• Click New and add the following:

  • %JAVA_HOME%\bin

• Click OK to save changes.

Step-3: Verify Java Installation

• Open a new Command Prompt window and run the following commands:

java -version

java version "21.0.4" 2024-07-16 LTS
Java(TM) SE Runtime Environment (build 21.0.4+8-LTS-274)
Java HotSpot(TM) 64-Bit Server VM (build 21.0.4+8-LTS-274, mixed mode)

• Also verify the JAVA_HOME value:
  • echo %JAVA_HOME% This should return:
  • C:\Program Files\Java\jdk-21

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3. Download and Install Jenkins

Step-1: Download Jenkins

• Go to the official Jenkins website and download the latest LTS version:
  • Jenkins LTS Download
• Choose the Windows installer (.msi).

Step-2: Install Jenkins

• Run the downloaded .msi file and follow the installation steps.
• During installation, Jenkins will check for a compatible Java version. If you've set up JAVA_HOME correctly, it should detect Java 21.

Step-3: Complete Jenkins Setup

• After installation, open Jenkins in your browser using:

  http://localhost:8080
  

• Use the initialAdminPassword located at:

  C:\ProgramData\Jenkins\.jenkins\secrets\initialAdminPassword
  

Step-4: Troubleshooting: Missing Secrets Directory and File

If you cannot see the secrets directory or the initialAdminPassword file, follow these steps:

1. Restart Jenkins:

   • Open the Run dialog (Windows + R), type services.msc, and press Enter.
   • Find Jenkins in the list, right-click on it, and select Restart.

2. Check the Secrets Directory:

   • Open Command Prompt and run:

     dir "C:\ProgramData\Jenkins\.jenkins\secrets"

3. Check Jenkins Log Files:

   • If the secrets directory is still missing, you can check the log files for any errors:

     type "C:\Program Files\Jenkins\jenkins.err.log"
     type "C:\Program Files\Jenkins\jenkins.out.log"

   • Follow the on-screen instructions to complete the Jenkins setup and create the admin user.

     Jenkins initial setup is required. An admin user has been created and a password generated.
     Please use the following password to proceed to installation:
     
     754240566b9e4748b1698f4f87ae9615
     
     This may also be found at: C:\ProgramData\Jenkins\.jenkins\secrets\initialAdminPassword
     

Step-5: Verify Jenkins Installation

• Ensure that Jenkins is running correctly by visiting:

  http://localhost:8080
  

• You can start/stop Jenkins via the Services management console in Windows.

Step-6: Jenkins Workspace

C:\ProgramData\Jenkins\.jenkins\workspace

Step-7: Set the JENKINS_HOME Environment Variable

• Make sure JENKINS_HOME is set to the directory where your existing Jenkins data is stored, such as "C:\Users\ADMIN.jenkins". This will help Jenkins load your previous configurations.

  set JENKINS_HOME="C:\Users\ADMIN\.jenkins"

• Or, if you want it permanently, you can set it through System Properties:

   Go to Control Panel > System > Advanced system settings > Environment Variables. Under System variables,
   click New and add JENKINS_HOME with the value "C:\Users\ADMIN\.jenkins".

Step-8: Start Jenkins with jenkins.exe

• You can start Jenkins using the .exe with this command to ensure it uses the JENKINS_HOME you set:

      "C:\Program Files\Jenkins\jenkins.exe" --httpPort=8080

Step-9: Alternative Start Command

• If the .exe option doesn’t load the existing configurations, try starting with jenkins.war while specifying JENKINS_HOME:

  java -Djenkins.home="C:\Users\ADMIN\.jenkins" -jar "C:\Program Files\Jenkins\jenkins.war" --httpPort=8080

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