Added config file loading and yaml support

config.yml

@@ -0,0 +1,2 @@
+{% import 'config.d/common.jinja' as common %}
+answer: {{ common.answer | yaml }}

config.yml.d/common.jinja

@@ -0,0 +1 @@
+{% set answer = 'The answer is: 42' %}

main.py

@@ -3,7 +3,22 @@
 import sys
 
 import argparse
+import jinja2
 import pydantic
+import yaml
+
+
+def to_yaml(value):
+    value_str = yaml.safe_dump(value, default_style='"', default_flow_style=True)
+    return value_str[:-1] if value_str and value_str[-1] == '\n' else value_str
+
+
+class ConfigBase(pydantic.BaseModel):
+    pass
+
+
+class ConfigRoot(ConfigBase):
+    answer: str = pydantic.Field()
 
 
 class Options(pydantic.BaseModel):
@@ -21,7 +36,27 @@ def main(argv):
 
     options = Options(**vars(args))
 
+    with open(options.config_path, 'r') as f:
+        config_template = f.read()
+
+    jinja_env = jinja2.Environment(
+        loader=jinja2.PrefixLoader({
+            'config': jinja2.DictLoader({
+                'config.yml': config_template
+            }),
+            'config.d': jinja2.FileSystemLoader('{}.d'.format(options.config_path))
+        }),
+        extensions=["jinja2.ext.do"]
+    )
+    jinja_env.filters['yaml'] = to_yaml
+
+    template = jinja_env.get_template('config/config.yml')
+    config_yml = template.render(options=options)
+    config_dict = yaml.safe_load(config_yml)
+    config = ConfigRoot(**config_dict)
+
     print(options.config_path)
+    print(config.answer)
 
     return 0
 

requirements.txt

@@ -1,2 +1,4 @@
-pydantic~=1.6.1
-argparse~=1.4.0
+argparse
+pydantic
+jinja2
+pyyaml