Unable to Connect to Jenkins Server (Amazon Linux AMI)

Question

When I had installed Jenkins on Amazon Linux AMI following steps mentioned in http://bhargavamin.com/how-to-do/install-jenkins-on-amazon-linux-aws/

After installation I was able to open Jenkins through browser but when I selected option "Install Plugins" it showed error as "Unable to connect to Jenkins Server."

So then how to troubleshoot this issue??

Answer 1

The problem here is pretty simple, if you do curl http://127.0.0.1:8080 on your host machine, you should get a message stating:

Authentication required
<!--
You are authenticated as: anonymous
Groups that you are in:

Permission you need to have (but didn't): hudson.model.Hudson.Administer
-->

This means that jenkins has anonymous priviledges which is not allowing any connection.

To solve this issue, you will have to do two changes:

1. Add Jenkins user to root group: sudo usermod -a -G root jenkins

2. Make Jenkins listen to all external IPs by editing file /etc/sysconfig/jenkins and changing the JENKINS_LISTEN_ADDRESS="0.0.0.0"

Once this is done, restart the jenkins server and then try to install plugins for jenkins.

Answer 2

I'm using this trick https://issues.jenkins-ci.org/browse/JENKINS-45388 and it works. What I did is add passwd: as prefix of file /var/lib/jenkins/secrets/initialAdminPassword and click retry button for several times and finally it works.