Allow to configure locale for docker builds

Dockerfile

@@ -12,7 +12,8 @@ FROM python AS sphinx_build
 WORKDIR /app
 COPY --from=composer /app /app
 RUN pip3 install Sphinx sphinx_rtd_theme
-RUN make html
+ARG language=en
+RUN make -e "SPHINXOPTS=-D language='${language}'" html
 
 FROM nginx
 WORKDIR /usr/share/nginx/html

README.md

@@ -39,6 +39,13 @@ $ docker-compose up --build
 
 Go to [http://localhost:8080/README.html](http://localhost:8080/README.html) to read the generated documentation.
 
+If you want to localize your documentation you can pass the locale as an argument to the docker build:
+
+```bash
+$ docker-compose build --build-arg language=de
+$ docker-compose up
+```
+
 ## Patterns
 
 The patterns can be structured in roughly three different categories. Please click on the [:notebook:](http://en.wikipedia.org/wiki/Software_design_pattern) for a full explanation of the pattern on Wikipedia.

docker-compose.yml

@@ -4,5 +4,7 @@ services:
     build:
       context: .
       dockerfile: Dockerfile
+      args: 
+        language: ${language:-en}
     ports:
       - "8080:80"