📝 Writing docs. (more detailed example)

Signed-off-by: mgorsk1 <[email protected]>

Author: mgorsk1

rfcs/028-simplify-config-customization.md

@@ -69,25 +69,83 @@ config_module_class = get_config_class('metadata', _config_module_class)
 Pseudocode:
 
 ##### Amundsen Common
+
 ```python
 import os
+from json import loads
+
 
 def get_config_class(component, base_class):
     prefix = f'AMUNDSEN__{component.upper()}__'
 
+    types_spec = [(str, lambda x: x),
+                  (int, lambda x: int(x)),
+                  (list, lambda x: x.split(',')),
+                  (dict, lambda x: loads(x))]
+
     class ConfigClass(base_class):
         def __init__(self, *args, **kwargs):
             super(ConfigClass, self).__init__(*args, **kwargs)
 
             for k, v in dict(os.environ).items():
                 if k.startswith(prefix):
-                    setting = k.split(prefix)[1]
+                    setting_name = k.split(prefix)[1]
+
+                    try:
+                        current_setting_value = getattr(self, setting_name)
+                        setting_type = type(current_setting_value)
+                    except AttributeError:
+                        print(f'You are trying to set not existing configuration setting: {k}')
+
+                        continue
+
+                    new_setting_value = None
 
-                    setattr(self, setting, v)
+                    for spec in types_spec:
+                        _type, _function = spec
+
+                        if issubclass(setting_type, _type):
+                            new_setting_value = _function(v)
+
+                            break
+
+                    if not new_setting_value:
+                        print(setting_name, setting_type)
+
+                        continue
+
+                    setattr(self, setting_name, new_setting_value)
 
     return ConfigClass
 ```
 
+##### Amundsen Metadata
+
+```python
+import os
+from amundsen_common.config import get_config_class
+
+
+class LocalConfig:
+    HOST_URL = 'http://localhost:1234'
+    LIST_OF_VARS = []
+    INT_SETTING = 0
+
+
+os.environ['AMUNDSEN__METADATA__HOST_URL'] = 'http://localhost:9999'
+os.environ['AMUNDSEN__METADATA__LIST_OF_VARS'] = 'a,b,c,d,e'
+os.environ['AMUNDSEN__METADATA__INT_SETTING'] = '2'
+os.environ['AMUNDSEN__METADATA__GIGGLES'] = 'http://localhost:9999'
+
+t = get_config_class('metadata', LocalConfig)()
+
+print(t.__dict__)
+
+# Output:
+# You are trying to set not existing configuration setting: AMUNDSEN__METADATA__GIGGLES
+# {'HOST_URL': 'http://localhost:9999', 'LIST_OF_STH': ['a', 'b', 'c', 'd', 'e'], 'SETTING_INT': 2}
+```
+
 ## Drawbacks
 
 N/A