So, I have been playing around with xenstore-ls and xenstore-read commands on my Virtual Machine in the cloud. Basically xenstore-ls and xenstore-read are used to retrieve variable information about the network settings which are passed to a vdi when it is being built. Also if the network configuration breaks there is a way to use xenstore-write to read the vm-data read only network variables and the nova agent will be called to reset it.
I am still familiarizing myself with this so apologies if there are any mistakes. This article will be updated as I learn more about it.
Commands available on Rackspace Virtual Machines
xenstore xenstore-chmod xenstore-exists xenstore-list xenstore-ls xenstore-read xenstore-rm xenstore-watch xenstore-write
There are several things we can do
1. Show the Data associated with the VM, including mem_free, mem_total of the instance, the OS version (8), the os_name, distro, and the uname for the kernel.
root@dingdong:~# xenstore-ls data
host = ""
meminfo_total = "1018872"
meminfo_free = "560180"
os_name = "Debian GNU/Linux 8.1 (jessie)"
os_majorver = "8"
os_minorver = "1"
os_uname = "3.16.0-4-amd64"
os_distro = "debian"
updated = "Fri Aug 28 17:30:00 BST 2015"
guest = ""
9cab4aed-0d29-4c7e-be2f-e15f1ed33231 = "{"message": "1.39.1", "returncode": "0"}"
6f38e0e1-6606-4245-8c8f-560c0204b419 = "{"message": "109108621899310233456141728258155", "returncode": "D0"}"
c96d2b6e-31fb-489f-882c-790da25dbe1a = "{"message": "", "returncode": "0"}"
be73ed2e-5c5a-4183-861b-2b6faaf8b09b = "{"message": "", "returncode": "0"}"
ad730c7c-3c5e-4ba7-bfcc-8400a2675566 = "{"message": "75660051671748071924891088737764", "returncode": "D0"}"
d3536286-4447-4f5b-84cc-8b6b1f61989c = "{"message": "", "returncode": "0"}"
PresentationForAdamOfHowXenstoreWork = "{"message": "", "returncode": "0"}"
As you can see from above my colleague was helping make a presentation for me as to how this actually works!
Listing all of the current vm-data
xenstore-ls vm-data
networking = ""
BC764E08E370 = "{"label": "private", "broadcast": "10.179.255.255", "ips": [{"ip": "10.179.197.101", "netmask": "255.255.192.0", "enabled": "1", "gateway": null}], "mac": \..."
BC764E086A56 = "{"ip6s": [{"ip": "2a00:1a48:7806:115:be76:4eff:fe08:6a56", "netmask": 64, "enabled": "1", "gateway": "fe80::def"}], "label": "public", "broadcast": "162.13\..."
meta = "{"rxtx_cap": 120.0}"
hostname = "dingdong"
auto-disk-config = "False"
provider_data = ""
ip_whitelist = ""
54 = "10.182.5.215"
53 = "134.213.147.236"
52 = "10.182.5.234"
51 = "134.213.148.114"
50 = "10.179.0.222"
49 = "10.179.75.22"
48 = "162.13.1.53"
47 = "95.138.174.55"
46 = "162.13.5.15"
45 = "10.177.132.233"
44 = "31.222.169.12"
43 = "10.179.0.234"
42 = "10.177.199.231"
41 = "10.179.0.159"
40 = "10.176.3.232"
39 = "10.176.3.236"
38 = "10.176.3.239"
37 = "10.176.3.235"
36 = "10.177.5.90"
35 = "10.177.5.89"
34 = "10.177.5.88"
33 = "10.177.1.73"
32 = "10.176.3.158"
31 = "10.177.0.105"
30 = "162.13.5.96"
29 = "5.79.25.90"
28 = "162.209.3.51"
27 = "162.13.22.243"
26 = "162.13.22.242"
25 = "166.78.7.98"
24 = "166.78.17.140"
23 = "166.78.24.91"
22 = "31.222.184.215"
21 = "31.222.184.38"
20 = "46.38.166.180"
19 = "46.38.160.93"
18 = "31.222.157.156"
17 = "31.222.177.183"
16 = "31.222.177.167"
15 = "31.222.164.168"
14 = "31.222.180.84"
13 = "31.222.161.245"
12 = "173.203.157.20"
11 = "119.9.12.98"
10 = "119.9.12.91"
9 = "162.13.1.53"
8 = "95.138.174.55"
7 = "162.209.4.155"
6 = "166.78.107.18"
5 = "50.56.249.239"
4 = "166.78.7.146"
3 = "89.234.21.64/28"
2 = "67.192.155.96/27"
1 = "173.203.5.160/27"
0 = "173.203.32.136/29"
roles = "["object-store:default", "compute:default", "identity:user-admin"]"
region = "lon"
provider = "Rackspace"
user-metadata = ""
build_config = ""monitoring_defaults,monitoring_agent_only,auto_updates""
rax_service_level_automation = ""Complete""
allowvssprovider = "false"
It is possible to retrieve specific information like networking configuration
xenstore-ls vm-data/networking
BC764E08E370 = "{"label": "private", "broadcast": "10.179.255.255", "ips": [{"ip": "10.179.197.101", "netmask": "255.255.192.0", "enabled": "1", "gateway": null}], "mac": "\..."
BC764E086A56 = "{"ip6s": [{"ip": "2a00:1a48:7806:115:be76:4eff:fe08:6a56", "netmask": 64, "enabled": "1", "gateway": "fe80::def"}], "label": "public", "broadcast": "162.13.\..."
The format here is kind of nasty, so there is a tool that we can use called jq
Filtering Network Data for MAC interfaces
apt-get update
apt-get install jq
xenstore-read vm-data/networking/BC764E086A56 | jq .
{
"ip6s": [
{
"ip": "2a00:1a48:7806:115:be76:4eff:fe08:6a56",
"netmask": 64,
"enabled": "1",
"gateway": "fe80::def"
}
],
"label": "public",
"broadcast": "162.13.86.255",
"ips": [
{
"ip": "162.13.86.79",
"netmask": "255.255.255.0",
"enabled": "1",
"gateway": "162.13.86.1"
}
],
"mac": "BC:76:4E:08:6A:56",
"gateway_v6": "fe80::def",
"dns": [
"83.138.151.81",
"83.138.151.80"
],
"gateway": "162.13.86.1"
}
Lots of cool stuff there. Including the Rackspace Service Net and Rackspace Public Net configurations. It’s possible to use jq to filter the JSON output of the xenstore-read command by filtering less.
Filtering ips network data with JQ
xenstore-read vm-data/networking/BC764E086A56 | jq .ips
[
{
"ip": "162.13.86.79",
"netmask": "255.255.255.0",
"enabled": "1",
"gateway": "162.13.86.1"
}
]
There are a lot more things that can be done, however this is all I have time for , today.
