Jenkins配置问题咨询：用户创建、登录及日志查看

Hey Rocky, let's work through each of your Jenkins issues step by step – I remember hitting similar roadblocks when I first started, so I know how confusing this can be!

1. 仪表盘无创建用户选项的问题 #

If you already created an admin user during initialization, the user management entry isn't on the main dashboard by default. Here's how to find it (and fix it if it's missing):

• If you can still access Jenkins with a privileged account: Navigate to Manage Jenkins > Manage Users – this is where you'll find the option to create new users.
• If you can't log in at all (ties into your second issue): You'll need to temporarily disable security to regain access:
  1. Locate your Jenkins home directory's config.xml file (I'll cover where this is in the next section).
  2. Find the line <useSecurity>true</useSecurity> and change it to <useSecurity>false</useSecurity>.
  3. Restart your Tomcat server. Once Jenkins reloads, you'll be able to access it without login prompts. Then head back to Manage Jenkins > Configure Global Security to re-enable security and set up user management properly.

2. Jenkins用户凭证的存储位置 #

Jenkins stores user-related data in two key places within your Jenkins home directory:

• Local user accounts: Look for the users folder. Each user has their own subfolder named after their username (e.g., users/admin/). Inside each folder, the config.xml file contains the user's details, including their encrypted password hash.
• Global credentials (like Git/Server credentials): These are stored in the root of the Jenkins home directory in the credentials.xml file.

To find your Jenkins home directory:

• On Linux/macOS: It's usually ~/.jenkins by default.
• On Windows: Check C:\Users\[Your Username]\.jenkins.
• If you can access Jenkins (even temporarily), go to Manage Jenkins > System Configuration – the path is listed under "Jenkins home directory".

3. 查看Jenkins日志及调试登录失败 #

Where to find logs #

You have two main log sources to check:

• Tomcat server logs: These live in your Tomcat installation's logs folder. On Linux/macOS, the most useful one is catalina.out; on Windows, look for localhost.log or localhost_access_log.*.txt. These logs capture all output from Jenkins running inside Tomcat.
• Jenkins internal logs: If you can access the Jenkins dashboard, go to Manage Jenkins > System Log. You can filter logs by level (like ERROR or WARNING) to zero in on login issues.

Debugging login failures #

• Check Tomcat logs first: Look for lines containing keywords like "Authentication failed" or "User not found" – these will tell you exactly why the login is failing (e.g., wrong password, disabled user, mismatched auth method).
• Reset admin password if needed: If you forgot the admin password, edit the users/admin/config.xml file in your Jenkins home directory:
  1. Find the <passwordHash> line and replace its value with this default hash: #jbcrypt:$2a$10$DdaWzN64JgUtLdvxWIflcuQu2fgrrMSAMabF5TSrGK5nXitqK9ZMS (this corresponds to the password admin).
  2. Save the file and restart Tomcat – you'll now be able to log in with admin/admin.
• Verify security settings: If you recently changed the authentication method (e.g., switched to LDAP), make sure your local admin user is still allowed to log in. Head to Manage Jenkins > Configure Global Security to check the "Security Realm" setting.

内容的提问来源于stack exchange，提问作者Rocky