Add deployment and improve Dockerfiles and CICD

backend/Dockerfile

@@ -1,18 +1,31 @@
-FROM golang:1.21.6
+# build stage
+FROM golang:alpine AS build
 
-# Set the Current Working Directory inside the container
 WORKDIR /app
 
-# Copy go mod and sum files
-COPY go.mod go.sum ./
-RUN go mod download
-
 # Copy the source from the current directory to the Working Directory inside the container
-COPY *.go ./
-COPY . .
+COPY . ./
+# download needed modules
+RUN apk add --no-cache --update go gcc g++ && \
+    go mod download && \
+    CGO_ENABLED=1 GOOS=linux go build -o /htwkalender
 
-# Build the Go app
-RUN CGO_ENABLED=1 GOOS=linux go build -o /htwkalender
+# production stage
+FROM alpine:latest AS prod
 
-# Expose port 8080 to the outside world
-EXPOSE 8080
+WORKDIR /htwkalender
+
+ARG USER=ical
+RUN adduser -Ds /bin/sh $USER && \
+    chown $USER:$USER ./
+
+USER $USER
+RUN mkdir -p data
+
+# copies executable from build container
+COPY --chown=$USER:$USER --from=build /htwkalender ./
+
+# Expose port 8090 to the outside world
+EXPOSE 8090
+
+ENTRYPOINT ["./htwkalender", "serve"]