This python example (contained in /SDK/client-examples/python/permute.py) demonstrates how to use XenMotion to move VMs simultaneously between hosts in a Resource Pool. The example makes use of asynchronous API calls and shows how to wait for a set of tasks to complete.

The program begins with some standard boilerplate and imports the API bindings module

import sys, time

import XenAPI

	

Next the commandline arguments containing a server URL, username, password and a number of iterations are parsed. The username and password are used to establish a session which is passed to the function main, which is called multiple times in a loop. Note the use of try: finally: to make sure the program logs out of its session at the end.

if __name__ == "__main__":
    if len(sys.argv) <> 5:
        print "Usage:"
        print sys.argv[0], " <url> <username> <password> <iterations>"
        sys.exit(1)
    url = sys.argv[1]
    username = sys.argv[2]
    password = sys.argv[3]
    iterations = int(sys.argv[4])
    # First acquire a valid session by logging in:
    session = XenAPI.Session(url)
    session.xenapi.login_with_password(username, password)
    try:
        for i in range(iterations):
            main(session, i)
    finally:
        session.xenapi.session.logout()

        

The main function examines each running VM in the system, taking care to filter out control domains (which are part of the system and not controllable by the user). A list of running VMs and their current hosts is constructed.

def main(session, iteration):
    # Find a non-template VM object
    all = session.xenapi.VM.get_all()
    vms = []
    hosts = []
    for vm in all:
        record = session.xenapi.VM.get_record(vm)
        if not(record["is_a_template"]) and \
           not(record["is_control_domain"]) and \
           record["power_state"] == "Running":
            vms.append(vm)
            hosts.append(record["resident_on"])
    print "%d: Found %d suitable running VMs" % (iteration, len(vms))

        

Next the list of hosts is rotated:

    # use a rotation as a permutation
    hosts = [hosts[-1]] + hosts[:(len(hosts)-1)]

        

Each VM is then moved via XenMotion to the new host under this rotation (i.e. a VM running on host at position 2 in the list will be moved to the host at position 1 in the list etc.) In order to execute each of the movements in parallel, the asynchronous version of the VM.pool_migrate is used and a list of task references constructed. Note the live flag passed to the VM.pool_migrate; this causes the VMs to be moved while they are still running.

    tasks = []
    for i in range(0, len(vms)):
        vm = vms[i]
        host = hosts[i]
        task = session.xenapi.Async.VM.pool_migrate(vm, host, { "live": "true" })
        tasks.append(task)

        

The list of tasks is then polled for completion:

    finished = False
    records = {}
    while not(finished):
        finished = True
        for task in tasks:
            record = session.xenapi.task.get_record(task)
            records[task] = record
            if record["status"] == "pending":
                finished = False
        time.sleep(1)

        

Once all tasks have left the pending state (i.e. they have successfully completed, failed or been cancelled) the tasks are polled once more to see if they all succeeded:

    allok = True
    for task in tasks:
        record = records[task]
        if record["status"] <> "success":
            allok = False


        

If any one of the tasks failed then details are printed, an exception is raised and the task objects left around for further inspection. If all tasks succeeded then the task objects are destroyed and the function returns.

    if not(allok):
        print "One of the tasks didn't succeed at", \
            time.strftime("%F:%HT%M:%SZ", time.gmtime())
        idx = 0
        for task in tasks:
            record = records[task]
            vm_name = session.xenapi.VM.get_name_label(vms[idx])
            host_name = session.xenapi.host.get_name_label(hosts[idx])
            print "%s : %12s %s -> %s [ status: %s; result = %s; error = %s ]" % \
                  (record["uuid"], record["name_label"], vm_name, host_name,      \
                   record["status"], record["result"], repr(record["error_info"]))
            idx = idx + 1
        raise "Task failed"
    else:
        for task in tasks:
            session.xenapi.task.destroy(task)

        

This example (contained in /SDK/client-examples/bash-cli/clone-vms) is a bash script which uses the XE CLI to clone a VM taking care to shut it down first if it is powered on.

The example begins with some boilerplate which first checks if the environment variable XE has been set: if it has it assumes that it points to the full path of the CLI, else it is assumed that the XE CLI is on the current path. Next the script prompts the user for a server name, username and password:

# Allow the path to the 'xe' binary to be overridden by the XE environment varia
ble
if [ -z "${XE}" ]; then
  XE=xe
fi

if [ ! -e "${HOME}/.xe" ]; then
  read -p "Server name: " SERVER
  read -p "Username: " USERNAME
  read -p "Password: " PASSWORD
  XE="${XE} -s ${SERVER} -u ${USERNAME} -pw ${PASSWORD}"
fi

	

Next the script checks its commandline arguments. It requires exactly one: the UUID of the VM which is to be cloned:

# Check if there's a VM by the uuid specified
${XE} vm-list params=uuid | grep -q " ${vmuuid}$"
if [ $? -ne 0 ]; then
        echo "error: no vm uuid \"${vmuuid}\" found"
        exit 2
fi

	

The script then checks the power state of the VM and if it is running, it attempts a clean shutdown. The event system is used to wait for the VM to enter state "Halted".

# Check the power state of the vm
name=$(${XE} vm-list uuid=${vmuuid} params=name-label --minimal)
state=$(${XE} vm-list uuid=${vmuuid} params=power-state --minimal)
wasrunning=0

# If the VM state is running, we shutdown the vm first
if [ "${state}" = "running" ]; then
        ${XE} vm-shutdown uuid=${vmuuid}
        ${XE} event-wait class=vm power-state=halted uuid=${vmuuid}
        wasrunning=1
fi

	

The VM is then cloned and the new VM has its name_label set to cloned_vm.

# Clone the VM
newuuid=$(${XE} vm-clone uuid=${vmuuid} new-name-label=cloned_vm)

	

Finally, if the original VM had been running and was shutdown, both it and the new VM are started.

# If the VM state was running before cloning, we start it again
# along with the new VM.
if [ "$wasrunning" -eq 1 ]; then
        ${XE} vm-start uuid=${vmuuid}
        ${XE} vm-start uuid=${newuuid}
fi