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Debugging check_http

Debugging check_http

This plugin tests HTTP/HTTPS services, follows redirects, checks content, connection times, and certificate expirations.

LAST TESTED ON CHECKMK 2.3.0P1

Table of Contents

check_http has many valuable configuration options. Please click here for some of the more common ones. 

 

Debugging

Proxy

In the following examples, you will see references to myproxyip and proxy_port. Please replace this information with your own proxy IP and port number.

 

Debugging with curl

If you have trouble using check_http, you can start to query the URL with curl:

curl -x myproxyip:proxy_port https://www.google.com/ --verbose

 

Execute the active Check manually

There are several ways to access the command. One way is described here: Execute active check manually.

One other way is with cmk -N:

OMD[mysite]:~/lib/nagios/plugins$ cmk -N |grep http check_command check_mk_active-http!'-u' 'https://www.google.com/' '--ssl' '--onredirect=follow' '-j' 'CONNECT' '--sni' '-p' 'proxy_port' 'myproxyip' 'www.google.com' command_line /omd/sites/mysite/lib/nagios/plugins/check_http $ARG1$ command_name check_mk_active-http

cmk -N will show you the nagios config. Active Checks in Checkmk are based on nagios.



A second way to access the command is via livestatus:

OMD[mysite]:~/lib/nagios/plugins$ lq "GET services\nColumns:host_name description check_command_expanded\nFilter: host_name = mysite\nFilter: description = myservicename" localhost;HTTPS HTTPS;check_mk_active-http!'-u' 'https://www.google.com/' '--ssl' '--onredirect=follow' '-j' 'CONNECT' '--sni' '-p' 'proxy_port' 'myproxyip' 'www.google.com'

In both cases: Copy the parameters after the '!' for executing the command later.



Now you need to run the check_http and paste the copied parameters:

OMD[mysite]:~/lib/nagios/plugins$ ./check_http '-u' 'https://www.google.com/' '--ssl' '--onredirect=follow' '-j' 'CONNECT' '--sni' '-p' 'proxy_port' 'myproxyip' 'www.google.com'

 

For a detailed log, you can use --verbose at the end of the command:

OMD[mysite]:~/lib/nagios/plugins$ ./check_http '-u' 'https://www.google.com/' '--ssl' '--onredirect=follow' '-j' 'CONNECT' '--sni' '-p' 'proxy_port' 'myproxyip' 'www.google.com' --verbose

 

For more information, you can use --help command flag.

OMD[mysite]:~/lib/nagios/plugins$ ./check_http --help

 

Debugging Regular Expressions (Regex)

Javascript

If there is any client-side or Javascript-related content, Checkmk will not be able to parse this information with regular expressions.

 

In the following example, we are using regular expressions on status.cloud.google.com to gather Access Content Manager information. 

Example Check HTTP service

 

The service check returns OK

Screenshot of HTTP check OK

 

Running the command by hand can help debug issues as well.

OMD[mysite]:~/lib/nagios/plugins$ ./check_http -u /regional/americas --ssl -l -R 'Access Context Manager' --sni -I status.cloud.google.com -H status.cloud.google.com HTTP OK: HTTP/1.1 200 OK - 584329 bytes in 4.511 second response time |time=4.511160s;;;0.000000;10.000000 size=584329B;;;0;

 

Some important options

  • Address (name / IP or Proxy)
    If you need a proxy to access the domain

  • Virtual host
    This is necessary if you have multiple domains and one host running

  • How to handle redirect
    How to handle redirected pages

  • Regular Expression to expect in content
    Used to parse particular content from websites.

  • HTTP Method
    Set to CONNECT if you're using a proxy

    Example configuration of Check HTTP service.

 

Useful Links

 

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