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  • Finally all computers have other standard build tools like svn and cvs installed and available in PATH.

Note that in the more recent Jenkins packages, the default JENKINS_HOME (aka home directory for the 'jenkins' user on Linux machines, e.g. Red Hat, CentOS, Ubuntu) is set to /var/lib/jenkins.

Scheduling strategy

Some slaves are faster, while others are slow. Some slaves are closer (network wise) to a master, others are far away. So doing a good build distribution is a challenge. Currently, Jenkins employs the following strategy:

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  • Allow port-forwarding from the master to your slaves within the firewall. The port-forwarding should be restricted so that only the master with its known IP can connect to slaves. With this set up in the firewall, as far as Jenkins is concerned it's as if the firewall doesn't exist.  If multiple hops are involved, you may wish to investigate how to do ssh "jump host" transparently using the ProxyCommand construct.  In fact,  with a properly configured "jump host" setup, even the master doesn't need to expose itself to the public Internet at all - as long as the organization's firewall allows port 22 traffic.
  • Use JNLP slaves and have slaves connect to the master, not the other way around. In this case it's the slaves that initiates the connection, so it works correctly with the NAT firewall.

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Running Multiple Slaves on the Same Machine

 It is possible Using a well established virtualization infrastructure such as Kernel-based Virtual Machine (KVM), it is quite easy to run multiple slave instances on a Windows machine, and single physical node.  Such instances can be running various Linux, *BSD UNIX, Solaris, Windows.  For Windows, one can have them installed as separate Windows services so they can start up on system startup. While the correct use of executors largely obviates the need for multiple slave instances on the same machine, there are some unique use cases to consider:

  • You want more configurability between the configured nodes. Say you have one node set to be used as much as possible, and the other node do be used only when needed.
  • You may have multiple Jenkins master installations building different things, and so this configuration would allow you to have slaves for more than one master on the same box. That's right, with Jenkins you really can serve two masters.
  • You may wish to leverage the easiness of starting/stopping/replacing virtual machines, perhaps in conjunction with Jenkins plugins such as the Libvirt Slaves Plugin.
  • You wish to maximize your hardware investment and utilization, at the same time minimizing operating cost (e.g. utility expenses for running idling slaves).

Follow these steps to get multiple slaves working on the same Windows box:

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