Docs: Added templating documentation

docs/source/first-steps.rst

@@ -73,6 +73,8 @@ Test cases:
         }
     }
 
+Hint: You can pass environment variables in parameters - see: :ref:`Templating` section.
+
 4. Running checks
 -----------------
 
@@ -90,7 +92,7 @@ The image will by default expose a HTTP endpoint.
 
 List of supported environment variables:
 
-- CHECK_INTERVAL="*/1 * * * *"
+- CHECK_INTERVAL="\*/1 \* \* \* \*"
 - WAIT_TIME=0
 - LAZY=false
 

docs/source/index.rst

@@ -46,6 +46,7 @@ Simple, easy to setup, easy to understand. Works perfectly with Docker.
    first-steps
    hooks
    reference
+   templating
    custom-scripts
    cache
 

docs/source/templating.rst

@@ -0,0 +1,37 @@
+.. _Templating:
+
+Templating
+==========
+
+In order to increase the security there is a `simple templating` mechanism that allows to inject variables into
+parameters you define that are passed to the checks.
+
+**Example:**
+
+.. code:: yaml
+
+    {
+        "type": "ssh-command",
+        "input": {
+            "user": "thesecurityman",
+            "host": "iwa-ait.org",
+            "port": 6200,
+            "password": "${ENV.IWA_SECURITY_MAN_PASSWD}",
+            "command": "/usr/bin/some-security-check --is-secure",
+            "expected_exit_code": 0,
+            "timeout": 30
+        }
+    }
+
+Reference table
+---------------
+
++--------------+------------------------------+--------------------------------------------------+
+| Pattern      | Example                      | Description                                      |
++==============+==============================+==================================================+
+| ${ENV.*}     | ${ENV.USER}                  | Injects an environment variable from the host    |
++--------------+------------------------------+--------------------------------------------------+
+| ${checkName} | http                         | Name of the currently executed check             |
++--------------+------------------------------+--------------------------------------------------+
+| ${date}      | 2019-10-31T07:53:45.380307   | Current date and time                            |
++--------------+------------------------------+--------------------------------------------------+