XenStore

This article will cover XenStore-related topics and CLI examples.

WARNING: The majority of these commands are meant to be run on the hypervisor/host. Unless otherwise noted, they should not be run on a guest VM (or Cloud Server).

• View all domain information for a given DOMID:

$ xenstore-ls /local/domain/123

• View the domain data for a given DOMID (note that the "host" is empty and the "guest" is not. That is what we want to see):

$ xenstore-ls /local/domain/123/data
host = ""
meminfo_total = "1022884"
meminfo_free = "181088"
os_name = "Debian GNU/Linux 7.1 (wheezy)"
os_majorver = "7"
os_minorver = "1"
os_uname = "3.2.0-4-amd64"
os_distro = "debian"
updated = "Wed Oct  9 05:41:29 UTC 2013"
guest = ""
 127a8ec3-ffff-4d0b-cccc-6f6c03faedf3 = "{"message": "0.0.1.37", "returncode": "0"}"
 a1262b0a-ffff-4b39-cccc-7c9c5a341bd4 = "{"message": "120060756033138162104944855769740", "returncode": "D0"}"
 5a6df0d1-ffff-4666-cccc-94bae5798776 = "{"message": "", "returncode": "0"}"
 dba8667d-ffff-469c-cccc-b46b25fadb8e = "{"message": "", "returncode": "0"}"

• This is what the above output should _not_ look like (note that does not have the "guest" entries):

$ xenstore-ls /local/domain/399/data
host = ""
 cacbdbd9-ffff-4fd7-cccc-906f15e0f9fd = "{"name":"version","value":"agent"}"
meminfo_total = "1022880"
meminfo_free = "460328"
os_name = "Debian GNU/Linux 7.1 (wheezy)"
os_majorver = "7"
os_minorver = "1"
os_uname = "3.2.0-4-amd64"
os_distro = "debian"
updated = "Wed Oct  9 05:13:43 UTC 2013"

• Check nova-agent version (useful for making sure nova-agent is running on the VM):

$ label=instance-XXXXXXX; uuid=`uuidgen`; domid=$(xe vm-list name-label=$label params=dom-id --minimal); \
  xenstore-write /local/domain/$domid/data/host/$uuid '{"name":"version","value":"agent"}'; sleep 10 ; \
  xenstore-read /local/domain/$domid/data/guest/$uuid ; unset label; unset uuid; unset domid;
$ #~OR~
$ echo -n 'Enter Name Label : ';read LABEL;DOMID=$(xe vm-list name-label=$LABEL params=dom-id --minimal);\
  UUID=$(uuidgen);xenstore-write /local/domain/$DOMID/data/host/$UUID '{"name":"version","value":"agent"}';sleep 5;\
  echo -ne "\nxapi reply : "; xenstore-read /local/domain/$DOMID/data/guest/$UUID ; \
  xenstore-rm /local/domain/$DOM/data/host/$UUID ; unset LABEL; unset UUID; unset DOMID;

• Re-configure/reset network of VM from host:

$ label=instance-XXXXXXX; uuid=$(uuidgen); domid=$(xe vm-list name-label=$label params=dom-id --minimal); \
  xenstore-write /local/domain/$domid/data/host/$uuid '{"name":"resetnetwork","value":""}'; sleep 10 ; \
  xenstore-read /local/domain/$domid/data/guest/$uuid ; unset label; unset uuid; unset domid;

Miscellaneous commands

$ xenstore-exists /local/domain/$DOMID/data/guest/${UUID}
$ xenstore-write /local/domain/$DOMID/data/host/${UUID} {"name": "resetnetwork", "value": ""}'
$ xenstore-write /local/domain/$DOMID/data/host/${UUID} {"name": "password", "value": "MY_PASSWORD"}'
$ xenstore-ls /local/domain/$DOMID/PVAddons
$ xenstore-ls /local/domain/$DOMID/vm-data/networking
$ xenstore-read /local/domain/$DOMID/vm-data/networking/$MAC # MAC address from previous command

XenStore commands to be run on guest VM

$ xenstore-ls data
$ xenstore-read data/os_name
$ xenstore-read data/meminfo_total
$ xenstore-ls vm-data
$ xenstore-list vm-data
$ xenstore-ls vm-data/networking
$ xenstore-read vm-data/networking/${MAC_ADDRESS}  # <- Replace with your actual MAC address
$ xenstore-read vm-data/hostname
$ xenstore-read vm-data/provider_data/roles
$ xenstore-read vm-data/provider_data/region
$ xenstore-read name
$ xenstore-read domid

• Advanced lookups:

$ xenstore-ls /local/domain/`xenstore-read domid`
$ xenstore-read vm-data/networking/$(xenstore-read device/vif/2/mac|sed 's/://g')|python -mjson.tool
$ xenstore-ls -f /local/domain/0/backend/vbd/1207/768  # <- Replace with your actual VBD values
$ xenstore-ls -f /local/domain/0/backend/vif/1207/2  # <- Replace with your actual VIF values