XAPI Host Plugins

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XAPI Host Plugins

"The XenAPI has an extension mechanism that allows one to install a Python script (usually, but it can be any executable) on the host side, and then call that through the XenAPI." - http://wiki.openstack.org/XenAPI

Writing a XenAPI plugin in Python is simplified by using the XenAPIPlugin module, which is by default installed in dom0 in XCP. Below is a simple XenAPI plugin which reverses a string passed to it:

#!/usr/bin/python

import XenAPIPlugin

def main(session, args):
    try:
        data = args["data"]
        return data[::-1]
    except KeyError:
        raise RuntimeError("No argument found with key 'data'.")

if __name__ == "__main__":
    XenAPIPlugin.dispatch({"main": main})

Save this code to /etc/xapi.d/plugins/reverse and make it executable. The plugin can then be run from the CLI like so:

# xe host-call-plugin host-uuid=<host-uuid> plugin=reverse fn=main args:data="hello, world"
dlrow ,olleh