Jenkins Slave Nodes – using the Swarm Plugin

 

 

I’ve been trying out a new (to me at least) way to add a Jenkins Slave Node – using UDP auto discovery via the Jenkins Swarm Plugin

This is a very easy and nice way to do it, with minimal configuration/hassle required so you can quickly and easily add new Jenkins Slave Nodes to your Master Jenkins instance as and when they are required.

Here are my notes from setting this up – it’s pretty simple to do and worked well for me out of the box…

Set up a new instance of Jenkins:

  • Make & cd to a working directory

mkdir jenkinsswarm; cd jenkinsswarm

  • Fetch jenkins.war

curl -O http://mirrors.karan.org/jenkins/war/1.506/jenkins.war

  • Start Jenkins

{/path/to/java/bin/}java -jar jenkins.war

After that, you should get console output along these lines…

Running from: /root/jenkinsswarm/jenkins.war
webroot: $user.home/.jenkins
18-Mar-2013 15:19:26 winstone.Logger logInternal
INFO: Beginning extraction from war file
Jenkins home directory: /root/.jenkins found at: $user.home/.jenkins
18-Mar-2013 15:19:33 winstone.Logger logInternal
INFO: HTTP Listener started: port=8080
18-Mar-2013 15:19:33 winstone.Logger logInternal
INFO: Winstone Servlet Engine v0.9.10 running: controlPort=disabled
18-Mar-2013 15:19:34 jenkins.InitReactorRunner$1 onAttained
INFO: Started initialization
18-Mar-2013 15:19:35 jenkins.InitReactorRunner$1 onAttained
INFO: Listed all plugins
18-Mar-2013 15:19:35 jenkins.InitReactorRunner$1 onAttained
INFO: Prepared all plugins
18-Mar-2013 15:19:35 jenkins.InitReactorRunner$1 onAttained
INFO: Started all plugins
18-Mar-2013 15:19:41 jenkins.InitReactorRunner$1 onAttained
INFO: Augmented all extensions
18-Mar-2013 15:19:41 jenkins.InitReactorRunner$1 onAttained
INFO: Loaded all jobs
18-Mar-2013 15:19:44 org.jenkinsci.main.modules.sshd.SSHD start
INFO: Started SSHD at port 25133
18-Mar-2013 15:19:44 jenkins.InitReactorRunner$1 onAttained
INFO: Completed initialization
18-Mar-2013 15:19:44 hudson.TcpSlaveAgentListener <init>
INFO: JNLP slave agent listener started on TCP port 41790
18-Mar-2013 15:19:44 hudson.WebAppMain$2 run
INFO: Jenkins is fully up and running

– that looks happy enough, and as you can see from the line “HTTP Listener started: port=8080” it’s running on the default port, so connect to http://yourhost:8080 and you should see something like this…

1_newJenkins

the next step is to install the Swarm Plugin (https://wiki.jenkins-ci.org/display/JENKINS/Swarm+Plugin) on this Jenkins Master instance so that Swarm Clients can connect to it.

Do this by going to “Manage Jenkins > Manage Plugins > Available” then selecting to install the “Swarm Plugin“.

Once that’s done you should see that the plugin has been installed…

2_installPlugin
Now that your new Jenkins server is set up and ready, hop over to your other Jenkins Slave/Client host and do the following…

mkdir for the swarm client

mkdir swarmclient; cd swarmclient/

Get the Swarm Client jar file from the ‘net

curl -O http://maven.jenkins-ci.org/content/repositories/releases/org/jenkins-ci/plugins/swarm-client/1.8/swarm-client-1.8-jar-with-dependencies.jar

Start up the Client

java -jar swarm-client-1.8-jar-with-dependencies.jar
Found 1 eligible Jenkins.
Connecting to http://mydomain.com:8080/
Attempting to connect to http://mydomain.com:8080/ a2721b16-04e4-0d962
18-Mar-2013 15:33:22 org.apache.commons.httpclient.HttpMethodDirector authenticateHost
WARNING: Required credentials not available for BASIC <any realm>@mydomain.com:8080
18-Mar-2013 15:33:22 org.apache.commons.httpclient.HttpMethodDirector authenticateHost
WARNING: Preemptive authentication requested but no default credentials available
18-Mar-2013 15:33:23 hudson.remoting.jnlp.Main$CuiListener <init>
INFO: Hudson agent is running in headless mode.
18-Mar-2013 15:33:23 hudson.remoting.jnlp.Main$CuiListener status
INFO: Locating server among [http://mydomain.com:8080/]
18-Mar-2013 15:33:23 hudson.remoting.jnlp.Main$CuiListener status
INFO: Connecting to myhost.mydomain.com:43932
18-Mar-2013 15:33:23 hudson.remoting.jnlp.Main$CuiListener status
INFO: Handshaking
18-Mar-2013 15:33:23 hudson.remoting.jnlp.Main$CuiListener status
INFO: Connected

Now take a look at your browser and you should see a new Node automatically added to the Master Jenkins instance…
3_slaveConnected

 

A very handy and flexible approach to adding/managing Nodes and workload – many thanks to the developers behind this!

Cheers,

Don

 

7 thoughts on “Jenkins Slave Nodes – using the Swarm Plugin”

  1. i am suing swarm plugin to create slave and run selenium testcases on the slave post build. Since swarm plugin starts the slave headless mode, all the selenium testcases are running background, hence the testcase fails asa it could not find the objects such as browser. Is there a way i can turn on this service in interactive mode.

  2. Use the official puppet jenkins module to fire up your slave. It uses swarm plugin. Or you could package swarm as a deb/rpm and have puppet install package when you fire up a VM to be used as a slave.

  3. What happen if we have more than one Jenkins masters in the network and we start swarm client? Which jenkins master it will get connected to? Is it like whatever it finds first it will connect to?

  4. Hi,
    Thanks for this wonderful write-up on swarm. I can successfully connect my slave to the master using swarm . But the connection is standalone. Is it possible that once we connect the slave to the master that connection can be converted into service so that slave connection will be up even if the machine restarts.

    Regards,
    Girish

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