Forum Discussion

Chris_Olson_172's avatar
Chris_Olson_172
Icon for Nimbostratus rankNimbostratus
Feb 23, 2016
Solved

Why does my health monitor fail?

Created and new http health monitor but as soon as I apply it all servers in the pool are marked down.

 

ltm monitor http enterprise_heartbeat_mon { defaults-from http destination : interval 5 ip-dscp 0 recv 200 send "GET /Enterprise/login.cmdx\r\n" time-until-up 0 timeout 16 }

 

From Fiddler:

 

Request Header GET /Enterprise/login.cmdx HTTP/1.1

 

Response Header HTTP/1.1 200 OK

 

Seems pretty simple but I must be missing something. Please advise....

 

application delivery
BIG-IP
LTM
  • Josiah_39459's avatar
    Josiah_39459
    Feb 23, 2016

    HTTP/1.1 requires a Host header and your send string does not include one. Try:

     

    send "GET /Enterprise/login.cmdx\r\nHost: host.example.com\r\n\r\n"

     

6 Replies

Sort By
  • Josiah_39459's avatar
    Josiah_39459
    Historic F5 Account
    Feb 23, 2016

    HTTP/1.1 requires a Host header and your send string does not include one. Try:

     

    send "GET /Enterprise/login.cmdx\r\nHost: host.example.com\r\n\r\n"

     

    • Chris_Olson_172's avatar
      Chris_Olson_172
      Icon for Nimbostratus rankNimbostratus
      Feb 23, 2016
      Thank you very much for your insight. It is still failing though. Forgive my ignorance but what is the best way to test the strings from the F5? ltm monitor http enterprise_heartbeat_mon { defaults-from http destination *:* interval 5 ip-dscp 0 recv 200 send "GET /Enterprise/login.cmdx\r\nHost: nextrelease.sample.com\r\n\r\n" time-until-up 0 timeout 16 }
    • Chris_Olson_172's avatar
      Chris_Olson_172
      Icon for Nimbostratus rankNimbostratus
      Feb 24, 2016
      Thank you for your assistance. The other issue was the receive string. I was advised I could use header information, thus the "200" recv string. That is incorrect. You have to use something (text, not pictured words) that is actually displayed on page. Once I did that, it worked.
  • gsharri's avatar
    gsharri
    Icon for Altostratus rankAltostratus
    Feb 23, 2016

    Monitors use HTTP 0.9 by default. Try this

     

    GET /Enterprise/login.cmdx HTTP/1.1\r\nHost: example.com\r\nConnection: Close\r\n

     

    See SOL2167 for send string details