Refactor Dockerfile to use ARG for versions

Author: Syntax3rror404

Dockerfile

@@ -1,5 +1,13 @@
-# Builder-Stage
-FROM golang:1.25.1-alpine3.22 AS builder
+# Variables
+ARG ALPINE_VERSION=3.22
+ARG GOLANG_VERSION=1.25.1
+
+FROM alpine:${ALPINE_VERSION} AS builder
+
+#
+# Builder-Stage ++++++++++++++++++++++++++++++++++++++++
+#
+FROM golang:${GOLANG_VERSION}-alpine${ALPINE_VERSION} AS builder
 WORKDIR /app
 
 COPY go.mod go.sum ./
@@ -8,14 +16,16 @@ RUN go mod download
 COPY . .
 RUN go build -o waitfor
 
-# Runner
-FROM alpine:3.22.1
+#
+# Final-Stage ++++++++++++++++++++++++++++++++++++++++
+#
+FROM alpine:${ALPINE_VERSION}
 
 # Create a non-root user "app" to run the application
-RUN addgroup -g 1000 app && adduser -u 1000 -G app -S app
+RUN addgroup -g 65532 app && adduser -u 65532 -G app -S app
 
 COPY --from=builder /app/waitfor /usr/local/bin/waitfor
 
-USER 1000:1000
+USER 65532:65532
 
-ENTRYPOINT ["waitfor"]
+ENTRYPOINT ["waitfor"]