Merge pull request #366 from bj00rn/feat/read-env-from-file

Read env variables from .env file if present

Author: nanomad

README.md

@@ -14,8 +14,17 @@ the [SAIC-iSmart-API Documentation](https://github.com/SAIC-iSmart-API/documenta
 
 ## Configuration
 
-Configuration parameters can be provided as command line parameters or environment variables (this is what you typically
+Configuration parameters can be provided as
+ * Command line parameters
+ * Environment variables (this is what you typically
 do when you run the service from a docker container).
+ * A local [.env file](https://saurabh-kumar.com/python-dotenv/#file-format) in current working directory (`CWD`) where the program is started from. When running in docker container the `CWD` container root is `/usr/src/app`.
+
+When using combinations of configuration methods, the order of precedence is as follows.
+
+  1. Command line parameters
+  2. Environment variables
+  3. Local .env file
 
 ### SAIC API
 
@@ -151,7 +160,9 @@ $ docker build -t saic-mqtt-gateway .
 
 There is a [docker compose file](docker-compose.yml) that shows how to set up the service.
 
-First setup the hidden ".env" file in the root directory of the project with your specific data
+First setup the hidden `.env` file in the root directory of the project with your specific data. The contents of this file will populate environment variables inside the container. 
+
+Alternatively, if you are conserned about security you can define your variables inside `.secret.env` and mount this file as `/usr/src/app/.env` in the container.
 
 Test your setup with
 ```

docker-compose.yml

@@ -13,4 +13,5 @@ services:
       - SAIC_PASSWORD=${SAIC_PWD}
       - CHARGING_STATIONS_JSON=/usr/src/app/config/charging-stations.json
     volumes:
+      # - ./.secret.env:/usr/src/app/.env:ro  # Uncomment to use a secret environment file
       - ./examples:/usr/src/app/config/

poetry.lock

@@ -21,6 +21,7 @@ dependencies = [
     'gmqtt (>=0.7.0,<0.8.0)',
     'inflection (>=0.5.1,<0.6.0)',
     'apscheduler (>=3.11.0,<4.0.0)',
+    'python-dotenv (>=1.1.1,<2.0.0)',
 ]
 
 [project.urls]

pyproject.toml

@@ -6,10 +6,16 @@
 import os
 from typing import TYPE_CHECKING, Any, override
 
+from dotenv import dotenv_values
+
 if TYPE_CHECKING:
     from collections.abc import Callable, Sequence
 
 
+# load .env file and merge with os.environ
+merged_environ = {**dotenv_values(".env"), **os.environ}
+
+
 class ArgumentHelpFormatter(argparse.RawTextHelpFormatter):
     """Custom argument formatter.
 
@@ -40,7 +46,7 @@ def _get_help_string(self, action: argparse.Action) -> str | None:
                     _help += _("\n(default: %(default)s)")
             # append environment variable
             _help += f"\n(environment variable: {action.envvar})"
-        # whitespace from each line
+        # strip whitespace from each line
         return "\n".join([m.lstrip() for m in _help.split("\n")])
 
 
@@ -53,8 +59,8 @@ def __init__(
         **kwargs: dict[str, Any],
     ) -> None:
         self.envvar = envvar
-        if os.environ.get(envvar):
-            default = os.environ[envvar]
+        if merged_environ.get(envvar):
+            default = merged_environ[envvar]
         if required and default:
             required = False
         super().__init__(default=default, required=required, **kwargs)