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Sunday, February 05, 2012

List of VMs on XenServer (with UUIDs)

Xen XE command is a very powerful tool, especially if you bind it with other UNIX tools such as awk. Let say we need a map of vm uuids and theirs names. We can use an output from the vm-list command and parse if with awk to get desire result.
xe vm-list | \
awk '{if ( $0 ~ /uuid/) {uuid=$5} if ($0 ~ /name-label/) \
{$1=$2=$3="";vmname=$0; printf "%s - %s\n", vmname, uuid}}'

The script first save the fifth column from a line having uuid string in it into the variable uuid. Next it saves all columns, after the third one, from line having name-label into variable vmname. Finally it prints both variables.

The exemplary output:

ukweb2 - fbca0851-35de-2963-bf0c-7980f3c0d96f
nagios - b741def2-14cc-def4-f8ba-ff0d3ed741d9
ukmail1 - 343c8f93-e4db-d0df-bc30-7544fcd6f14e
jira - ecc3241f-ac14-0398-4e44-ba96cd1d51d2
dodb-02 - 7f223172-e43e-a200-6dc6-b108ce4f9166
RTST-Witness Server - 3c236b0a-209f-6ac9-6d46-b14f7678bfa6
hub-01 - 60ef767c-9b87-edf8-9f13-af2185e656cd
ukweb1 - 6e0e4622-ddfe-0db8-a128-f432e05565cb
dns2 - d65e40d4-ea21-1cbf-cc86-9f522f5e04ef
ixchariot - 73f78129-86db-fd9f-81b4-85768eeee487

We can modify our command to prepare a list of all host with vms bind to them. This time we use xe vm-list with params=all option. The scripts searches for lines with the name-label and saves a name (third column). Next it looks for lines with the word affinity and a uuid (we know that UUID have to start from a hexadecimal number) and prints a saved name.

xe vm-list params=all| \
awk '{if ( $0 ~ /name-label/) {$1=$2=$3=""; vmname=$0} \
if ($0 ~ /affinity.*\:\ [a-e,0-9]/) {host=$4; printf "%s \n", vmname}}'

The output might looks similar to:

Control domain on host: p1-m4 
   Control domain on host: p1-m2 
   Control domain on host: p1-m3 
   Control domain on host: p1-m1 

You might wonder why the list is so short, but we have the list of machine enforce to start from a given host (affinity to a given UUID). If you have machine on share storage allowed to flow between machine you should get very short list indeed.
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