Forum Discussion
NimbostratusNew monitor looking for a character string is not working
Good morning, I created a new monitor on my LTM which makes an HTTP GET request and looks for a specific string.
Send String: GET /User/MobileSiteStart/List\r\n
Receive String: WAP
I use something similar in a 3rd party tool (Site 24x7) to tell whether the application running on the server is available for user requests. Unfortunately, the node in this case remains down. Am I missing a component someplace?
Thanks in advance!
3 Replies
cjuniorNacreous
Hi, It is a standard HTTP monitor?
Try:GET /User/MobileSiteStart/List HTTP/1.0\r\n\r\n
or
GET /User/MobileSiteStart/List HTTP/1.1\r\nHost: www.hostname.com\r\nConnection: Close\r\n\r\n
Hope this helps.
natheCirrocumulus
Jeff, have you seen this askf5 solution article? Should help if not.
https://support.f5.com/kb/en-us/solutions/public/2000/100/sol2167.html
What about if u do curl from the bigip with your send string? Does the required receive string show? Best in mind the receive string has to be within the first 5120 bytes of the response.
N
THiTo clarify why to use this particular syntax:
RFC 2616 (Hypertext Transfer Protocol -- HTTP/1.1) states:
" A client MUST include a Host header field in all HTTP/1.1 request messages . If the requested URI does not include an Internet host name for the service being requested, then the Host header field MUST be given with an empty value.
...
All Internet-based HTTP/1.1 servers MUST respond with a 400 (Bad Request) status code to any HTTP/1.1 request message which lacks a Host header field."
I have seen that omitting the "Host" header will usually result service "down" and so prefer using the format cjunior proposes. Note the double crlf sequence in the end and also the Connection: Close -header. The exact syntax is dependent upon sw version used. See more on this at: SOL2167: Constructing HTTP requests for use with the HTTP or HTTPS application health monitor
