add doc page

docs/20_Checks/_index.md

@@ -25,6 +25,7 @@ There is one include script used by all checks:
 * [check_fs_writable](check_fs_writable.md)
 * [check_haproxy_health](check_haproxy_health.md)
 * [check_haproxy_status](check_haproxy_status.md)
+* [check_http](check_http.md)
 * [check_memory](check_memory.md)
 * [check_mysqlserver](check_mysqlserver.md)
 * [check_netio](check_netio.md)

docs/20_Checks/check_httpd.md

+# Check Httpd
+
+## Introduction
+
+Makes an http request with a given method.
+Additionally you can verify the response.
+
+## Requirements
+
+* `curl` binary
+
+## Syntax
+
+```txt
+______________________________________________________________________
+
+CHECK_HTTP
+v1.0
+
+(c) Institute for Medical Education - University of Bern
+Licence: GNU GPL 3
+
+https://os-docs.iml.unibe.ch/icinga-checks/Checks/check_http.html
+______________________________________________________________________
+
+Makes an http request with a given method.
+Additionally you can verify the response by
+- http status code
+- content in http response header
+- content in http response body
+- content that is NOT in http response body
+
+SYNTAX:
+  check_http [-h]
+  check_http [-m METHOD] -u URL \
+      [-b REGEX] [-j FILTER] [-n REGEX] \ 
+      [-r REGEX] \
+      [-s STATUSCODE] \
+      [-l LABEL]
+
+OPTIONS:
+
+  -h               this help
+
+PARAMETERS:
+
+  Define request:
+  -u URL           Set url to fetch; eg. https://www.example.com/
+  -m METHOD        Set a method, eg. HEAD; default: GET
+
+  What to check:
+  -s STATUSCODE    exact Statuscode to check; 3 digits; by default critical
+                   is a statuscode greater equal 400
+  -r REGEX         Regex must match in http response header
+  -j JQ-FILTER     for JSON Response: filter data by a jq
+  -b REGEX         Regex must match in response body
+  -n REGEX         Regex must NOT match in response body
+
+  Output:
+  -l LABEL         set a custom label; default: METHOD + URL eg.
+                   "GET https://example.com/status"
+
+EXAMPLES:
+
+  check_http -u https://www.example.com/
+                   Check if GET request to url responds with 200..3xx status. 
+
+  check_http -m HEAD -u https://www.example.com/
+                   Check if HEAD request to url responds with 200..3xx status
+
+  check_http -u [URL] -s 403
+                   Check if the GET request to url has a wanted status code.
+                   You can verify if a protected url is not accessible.
+
+  check_http -u [URL] -b "contact"
+                   Check if the GET request to url responds with 200..3xx 
+                   status and the response body contains "contact".
+
+  check_http -u [URL] -n "error occured"
+                   Check if the GET request to url responds with 200..3xx 
+                   status and the response body NOT contains "error occured".
+
+  check_http -u [URL] -s 200 -b -b "contact" -n "error occured"
+                   Combine code, a matching search and a non matching one.
+
+```
+
+## Examples
+
+### Simple check of an url
+
+``check_http -u https://www.example.com/`` is a check that makes an http GET request.
+The queck is OK if the responded status code is no error - if it is 2xx (OK) or a redirect (3xx).
+
+```txt
+OK: GET https://www.example.com/ (200)
+
+Command: curl -si -X GET https://www.example.com/
+
+Found:
+- Http status is a 2xx OK [200];
+```
+
+### Http HEAD of an url
+
+You can set the method with ``-m``.
+``./check_http -m head -u https://www.example.com/`` responds
+
+
+```txt
+OK: HEAD https://www.example.com/ (200)
+
+Command: curl -si -X HEAD https://www.example.com/
+
+Found:
+- Http status is a 2xx OK [200];
+```
+
+### Exact status code
+
+With ``-m`` you can verify if the status code matches exactly a given value.
+You also can set a code for http error to ensure if a protected url really is blocking the request.
+
+Maybe you don't deny the access like 
+
+* ``./check_http -u https://www.example.com/memberarea -s 403``
+* ``./check_http -u https://www.example.com/config/settings.json -s 403``
+
+Or you can check a flag file that must be absent.
+
+* ``./check_http -u https://www.example.com/flag_maintenance.txt -s 404``
+
+### Matching content
+
+You can verify if the response matches a given regex. You can search in the response header with ``-r REGEX`` and in the response body with ``-b REGEX``.
+
+``check_http -u [URL] -b "contact"`` will resppns OK if the status code is not an error (lower 400) and the word "contact" is found in response body.