feat: use multi-stage build docker image

Dockerfile

@@ -1,7 +1,34 @@
-FROM golang:alpine
-RUN apk update && apk add --no-cache git
+# Stage 1: Build Stage
+FROM golang:alpine AS builder
+RUN apk add --no-cache git
 WORKDIR /app
+
+# Copy go.mod to cache dependencies
+COPY go.mod ./
+RUN go mod download
+
+# Copy the rest of the source code
 COPY . .
-RUN go mod tidy
+
+# Build the Go binary and name it 'binary'
 RUN go build -o binary
+
+# Stage 2: Minimal Runtime Stage
+FROM alpine:latest
+WORKDIR /app
+
+# Copy the binary from the builder stage
+COPY --from=builder /app/binary /app/binary
+
+# Copy the SSL certificate and key files into the image
+COPY server.crt server.key /app/
+
+# Set a non-root user for security
+RUN addgroup -S appgroup && adduser -S appuser -G appgroup
+USER appuser
+
+# Expose port 443 for HTTPS
+EXPOSE 443
+
+# Set the entry point to run the 'binary' binary
 ENTRYPOINT ["/app/binary"]