Posts Tagged Hudson

Jenkins CI Slave on Ubuntu 10.04 Lucid LTS Howto

Install Sun Java:

sudo add-apt-repository ppa:sun-java-community-team/sun-java6
sudo apt-get update
sudo apt-get install sun-java6-jdk

Ensure a SSH server is installed

sudo apt-get install openssh-server

Create a new Jenkins user and create the /var/jenkins directory – this will be our working directory.

sudo useradd -m jenkins
sudo mkdir /var/jenkins
sudo chown jenkins:jenkins /var/jenkins

Generate a public / private keypair and set the public key as an allowed host

#Enter file in which to save the key (/root/.ssh/id_rsa):
#Do not enter a Passphrase
#You should now have two files in /var/jenkins: a private.key and a, we want to cat the public key into our authorized keys file
su jenkins
cat > ~/.ssh/authorized_keys

The private key must be transfered to an accessible directory on the primary build server. Eg: C:\private.key or a more suitably protected location.

Login to your Jenkins install, select the plugin manager and install the SSH Slaves plugin. After restarting Jenkins to complete the install, click on Manage Jenkins followed by Manage Nodes and create a new dumb node with a name of your liking.

Configuration parameters:

Remote FS Root: /var/jenkins
Launch Method: Launch slave agents on Unix machines via SSH

Host: <Ubuntu Hostname>
Username: jenkins
Private key file: File of the private key (eg: C:\private.key)

When you press save, the slave should attempt to start automatically. If the start fails, check the log provided by jenkins and the server log.

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Hudson (Jenkins) and Git HTTP authentication

I run a Hudson, (now Jenkins) CI server on windows XP.
The Jenkins git plugin is broken if you have repositories that use HTTP auth (See:,

If you try to run a build on a job with a repo using HTTP auth, the process will hang at the repository checkout, as GIT is waiting for a password to be entered. Fortunately, you can set the credentials for the server access in a netrc file placed in your home directory.

Find your home directory:

  • If you are running Jenkins as the user you are currently logged in as:
    • Commonly, the home directory that GIT will use can be found by going start->Run and typing a “.” in the run dialog (without the quotes). On windows XP this is “C:\Documents and Settings\Administrator”
    • To be extra sure, you should open the GIT bash, type “cd” to go back to your home directory, and then enter “pwd” to show the current path.
  • If you are running Jenkins as a service
    • Create a new Execute Shell build step. Execute the command:
      echo $HOME
    • Run the build and examine the output to see where $HOME is located

Create the _netrc file:
On linux, this file is actually .netrc, however I found that on windows its using the underscore notation. When creating the _netrc file, ensure that your editor is saving the file using unix-line-endings. If you are using a tool like notepad++ this can be set by going Edit -> EOL Conversion -> UNIX Format.

_netrc contents:

machine <server name>
       login <server username>
       password <server password>

Where <server name> is the name of the server that hosts your GIT repository, and the username and password correspond to valid HTTP credentials. See the netrc page in references below for additional examples.

Verify the _netrc settings work by attempting to download the HEAD from the repository using curl:

curl --netrc --location -v http://<server_name>/<git_repo>.git/HEAD

This should return something like “ref: refs/heads/master“. If you get an authentication failed message, be sure to scroll up in the console to verify if curl was able to find the server entry in _netrc.


  • If you specify the address to the GIT repository in Hudson in http://<username>@<server> notation, the _netrc data will not be picked up. This is because of the “<username>@” prefix
  • I had to modify the git executable I was using, as the default wasn’t picking up the _netrc file
    • Under Manage Hudson -> Configure -> Git Installation, point the default executable to the git.cmd script. Mine was at C:\Program Files\Git\cmd


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