Added variables to command line utility #39

Author: nemesifier

bin/netjsonconfig

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 
+import os
 import sys
 import six
 import argparse
@@ -143,6 +144,7 @@ def print_output(output):
 args = parser.parse_args()
 config = _load(args.config)
 templates = [_load(template) for template in args.templates]
+context = dict(os.environ)
 method = args.method
 method_arguments = parse_method_arguments(args.args)
 
@@ -153,7 +155,7 @@ backends = {
 
 backend_class = backends[args.backend]
 try:
-    instance = backend_class(config, templates=templates)
+    instance = backend_class(config, templates=templates, context=context)
 except TypeError as e:
     print('netjsonconfig: invalid JSON passed in config or templates')
     sys.exit(2)

docs/source/general/basics.rst

@@ -271,6 +271,8 @@ it's possible to pass multiple templates that will be added one on top of the
 other to build the resulting *configuration dictionary*, allowing to reduce or
 even eliminate repetitions.
 
+.. _configuration_variables:
+
 Context: configuration variables
 --------------------------------
 

docs/source/general/commandline_utility.rst

@@ -67,3 +67,17 @@ Here's the common use cases explained::
 Using templates::
 
     netjsonconfig -c config.json -t template1.json template2.json -b openwrt -m render
+
+Environment variables
+---------------------
+
+*Environment variables* are automatically passed to the ``context`` argument (if you don't
+know what this argument does please read ":ref:`configuration_variables`"), therefore
+you can reference environment variables inside *configurations* and *templates*::
+
+    export HOSTNAME=freedom
+    netjsonconfig -c '{"general": { "hostname": "${HOSTNAME}" }}' -b openwrt -m render
+
+You can also avoid using ``export`` and write everything in a one line command::
+
+    PORT=2009; netjsonconfig -c config.json -t template1.json -b openwrt -m render

tests/test_bin.py

@@ -121,3 +121,10 @@ def test_generate_redirection(self):
         tar = tarfile.open('test.tar.gz', 'r')
         self.assertEqual(len(tar.getmembers()), 1)
         tar.close()
+
+    def test_context(self):
+        config = json.dumps({'general': {'description': '${DESC}'}})
+        command = "export DESC=testdesc; netjsonconfig --config '{0}' -b openwrt -m render".format(config)
+        output = subprocess.check_output(command, shell=True).decode()
+        self.assertNotIn('${DESC}', output)
+        self.assertIn('testdesc', output)