Merge pull request #29 from rebortg/improve/commandscripting

Improve/commandscripting

docs/commandscripting.rst

@@ -49,3 +49,59 @@ Unlike a normal configuration sessions, all operational commands must be prepend
   run show interfaces
 
   exit
+
+Other script language
+---------------------
+
+If you want to script the configs in a language other than bash you can have your script output commands and then source them in a bash script.
+
+Here is a simple example:
+
+.. code-block:: python
+
+  #!/usr/bin/env python
+  print "delete firewall group address-group somehosts"
+  print "set firewall group address-group somehosts address '1.1.1.1'"
+  print "set firewall group address-group somehosts address '1.1.1.2'"
+
+
+.. code-block:: sh
+
+  #!bin/vbash
+  source /opt/vyatta/etc/functions/script-template
+  
+  configure 
+  source <(/config/scripts/setfirewallgroup.py)
+  commit
+
+
+Executing Configuration Scripts
+-------------------------------
+
+There is a pitfall when working with configuration scripts. It is tempting to call configuration scripts with "sudo" (i.e., temporary root permissions), because that's the common way on most Linux platforms to call system commands.
+
+On VyOS this will cause the following problem: After modifying the configuration via script like this once, it is not possible to manually modify the config anymore:
+
+.. code-block:: sh
+
+  sudo ./myscript.sh # Modifies config
+  configure
+  set ... # Any configuration parameter
+
+| This will result in the following error message: ``Set failed``
+| If this happens, a reboot is required to be able to edit the config manually again.
+
+To avoid these problems, the proper way is to call a script with the ``vyattacfg`` group, e.g., by using the ``sg`` (switch group) command:
+
+.. code-block:: sh
+
+  sg vyattacfg -c ./myscript.sh
+
+
+To make sure that a script is not accidentally called without the ``vyattacfg`` group, the script can be safeguarded like this:
+
+.. code-block:: sh
+
+  if [ "$(id -g -n)" != 'vyattacfg' ] ; then
+      exec sg vyattacfg -c "/bin/vbash $(readlink -f $0) $@"
+  fi