Understanding Jenkins Distributed (Master‑Slave) Architecture and Common Issues

1. Jenkins Distributed Concept

In Jenkins distributed architecture, multiple slave nodes are used; when many projects need building, slaves take on the master’s workload and create projects on the slaves.

2. Slave environment must match the master

Any software installed on the master must also be prepared on the slave, preferably with identical paths; the only difference is that Jenkins itself does not need to be installed on the slave.

Jenkins Master‑Slave Architecture Overview:

a. The Master‑Slave distributed architecture solves the problem of a single Jenkins instance handling many build tasks, high load, and insufficient performance.

b. Master/Slave corresponds to the server and agent concepts.

c. The Master provides a web interface for users to manage jobs and slaves.

d. Jobs can run on the master machine or be assigned to a slave for execution.

e. One master (the machine hosting Jenkins) can be linked to multiple slaves to serve different jobs or the same job with different configurations.

3. Node Errors

3.1 SSH connection failure handling:

[root@jenkins-master jenkins]# pwd

/var/lib/jenkins

[root@jenkins-master jenkins]# cp -r /root/.ssh .

[root@jenkins-slave .ssh]# pwd

/var/lib/jenkins/.ssh

3.2 Cause of JDK version mismatch

[SSH] Starting agent process: cd "/var/lib/jenkins" && java -jar remoting.jar -workDir /var/lib/jenkins -jar-cache /var/lib/jenkins/remoting/jarCache

Mar 15, 2023 5:18:35 AM org.jenkinsci.remoting.engine.WorkDirManager initializeWorkDir

INFO: Using /var/lib/jenkins/remoting as a remoting work directory

Mar 15, 2023 5:18:35 AM org.jenkinsci.remoting.engine.WorkDirManager setupLogging

INFO: Both error and output logs will be printed to /var/lib/jenkins/remoting

Solution:

[root@jenkins-slave jdk11]# which java

/bin/java

[root@jenkins-slave jdk11]# ln -sf /usr/local/jdk11/bin/java /usr/bin/java

[root@jenkins-slave jdk11]# ll /usr/bin/java

lrwxrwxrwx 1 root root 25 Mar 15 05:30 /usr/bin/java -> /usr/local/jdk11/bin/java

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