This plugin tests the HTTP service on the specified host. It can test normal (HTTP) and secure (HTTPS) servers, follow redirects, search for strings and regular expressions, check connection times, and report on certificate expiration times.
Important Options
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: Check Email (check_mail)
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/cme2/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 = localhost\nFilter: description = HTTPS HTTPS" 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
Information on errors with Javascript
Some important options
- Address (name / IP or Proxy) → If you need a proxy to access the domain
- Virtual host → 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 →
- HTTP Method → Set to CONNECT if you're using a proxy
Disable SSL/TLS hostname extension support (SNI) →
Useful Links
- List of public proxies for debugging: https://spys.one/free-proxy-list/DE/
- https://www.monitoring-plugins.org/doc/man/check_http.html
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