Clean up new image leftovers (#314)

* Remove unused `.env.sample` file

* Update some comments

docker/DockerfileUIDev

@@ -10,7 +10,7 @@ RUN npm install
 COPY src/frontend .
 VOLUME ["/app/"]
 
-# serve the application
+# serve the application in development mode
 CMD npm run serve & tail -f /dev/null
 
 EXPOSE 8080

docker/DockerfileUIProd

@@ -6,17 +6,17 @@ WORKDIR /app
 COPY src/frontend/package*.json ./
 RUN npm install
 
+# Install webserver
+RUN npm install -g http-server
+
 # get MicroPowerManager source code and configuration
 COPY src/frontend .
 
 # Copy the entrypoint script to the container and make it executable
 COPY docker/entrypoint-ui-prod.sh /usr/local/bin/
 RUN chmod +x /usr/local/bin/entrypoint-ui-prod.sh
 
-# Set the entrypoint script to run when the container starts
+# serve the application via entrypoint script
 ENTRYPOINT ["/usr/local/bin/entrypoint-ui-prod.sh"]
 
-# Install http-server globally
-RUN npm install -g http-server
-
 EXPOSE 8081

docker/entrypoint-ui-prod.sh

@@ -1,19 +1,15 @@
 #!/bin/sh
 
-cd /app
-npm run build
+# This script builds the production application at container runtime before serving it
+# via webserver.
+# This is enable the use of environment variables in the production container.
+# As VueJS bundles the environment variables value into the application,
+# see https://cli.vuejs.org/guide/mode-and-env.html#environment-variables
 
-http-server dist -p 8081 
+# An alternative approach would be to use a tool like:
+# https://import-meta-env.org/
 
+cd /app
+npm run build
 
-# -----------------------------------------------------------------------------
-# Dockerfile for MPM frontend production docker image
-# -----------------------------------------------------------------------------
-# This Dockerfile sets up the environment to build and run the frontend. 
-# The main objective is to create a production-ready Docker image 
-# that serves the frontend  using http-server.
-#
-# The approach taken here is to use an entrypoint script as a workaround to handle
-# the loading of environment variables. This ensures that any dynamic environment 
-# variables required at runtime are correctly 
-# applied before starting the server.
+http-server dist -p 8081