Add incremental dockerfiles

04-building-container-images/sample-app/api-golang/Dockerfile.3

@@ -0,0 +1,17 @@
+# Pin specific version for stability
+# Use alpine for reduced image size
+FROM golang:1.19-alpine
+
+WORKDIR /app 
+
+# Copy only files required to install dependencies (better layer caching)
+COPY go.mod go.sum ./
+
+RUN go mod download
+
+COPY . .
+
+# Compile application during build rather than at runtime
+RUN go build -o api-golang
+
+CMD ["./api-golang"]