docs: describe how to configure via environment variables

Author: matthiasschaub

config/sample.config.toml

@@ -1,3 +1,3 @@
 # required configuration variables for docker compose setup
-# broker-url = "redis://redis:6379"
-# result-backend = "db+postgresql://smt:smt@postgres:5432"
+# broker_url = "redis://redis:6379"
+# result_backend = "db+postgresql://smt:smt@postgres:5432"

docs/configuration.md

@@ -1,6 +1,8 @@
 # Configuration
 
-The Sketch Map Tool can be configured using a configuration file.
+The Sketch Map Tool can be configured using a configuration file or via
+environment variables. The latter takes precedence over the former.
+
 
 ## Configuration File
 
@@ -15,6 +17,7 @@ To create a new configuration file simply copy the sample configuration file and
 cp config/sample.config.toml config/config.toml
 ```
 
+
 ## Default Configuration
 
 For a list of all configuration variables and their default values please take a look at [config.py](sketch_map_tool/config.py).
@@ -24,13 +27,23 @@ All lot of configuration values come with defaults.
 For running the services using Docker Compose set broker URL and result backend to:
 
 ```toml
-broker-url = "redis://redis:6379"
-result-backend = "db+postgresql://smt:smt@postgres:5432"
+broker_url = "redis://redis:6379"
+result_backend = "db+postgresql://smt:smt@postgres:5432"
+```
+
+
+## Environment Variables
+
+All environment variables are prefixed with `SMT_`. For example above
+configuration via environment variables is done like this:
+
+```sh
+SMT_BROKER_URL="redis://redis:6379"
+SMT_RESULT_BACKEND="db+postgresql://smt:smt@postgres:5432"
 ```
 
-## Misc
 
-### ArcGIS/ESRI API Key
+## ArcGIS/ESRI API Key
 
 To retrieve up-to-date attribution an ArcGIS/ESRI API key is needed.
 For local development you do not need one.

docs/development-setup.md

@@ -104,8 +104,6 @@ uv run ruff check --fix
 
 ### Tests
 
-Provide required [configuration variables](/docs/configuration.md#required-configuration) in `config/test.config.toml`. Be sure *not* to set `broker-url` and `result-backend`.
-
 To execute all tests run:
 ```bash
 uv run pytest