is this script running on the primary blade?
Problem this snippet solves:
Often, for example in an external monitor script, it is desirable for the script to execute only on the primary blade of a VIPRION cluster. Traditionally, in BIG-IP, a script has executed "tmsh show sys cluster" and then parsed the output (with "grep" and "awk") to derive a value which indicates whether it is running on the primary blade. However, there is another way to find out, using a different command ("bladectl") which runs more quickly and with less overhead than "tmsh".
How to use this snippet:
Embed this one-liner into your script, with appropriate surrounding logic. If running on the primary, it returns '1'. If running on a secondary blade, it returns '0'.
Code :
/usr/sbin/bladectl -g leds | /bin/sed -n 'y/:/ /;/Primary LED is[ ]*solid[ ]*Green/p' | /bin/awk -F " " '{ print $2}'Tested this on version:
13.0
3 Comments
- TimRiker
Cirrocumulus
This returns "2" on both blade 1 and blade 2 of a test cluster running 13.1.1.4, where blade 2 is currently master.
Here's the same in just awk:
/usr/sbin/bladectl -g leds | /bin/awk '/slot.*Primary LED.*solid.*Green*/ {gsub(":","",$2);print $2}' What BIG-IP release is this test cluster running?
- TimRiker
Running 13.1.1.4, I updated the original comment. The point is that the script shows the active blade, but does not check the blade we are currently on. Presumably this would need to parse /var/prompt/ps1 ?
