Add incremental dockerfiles

04-building-container-images/sample-app/api-golang/Dockerfile.6

@@ -0,0 +1,47 @@
+# Pin specific version for stability
+# Use separate stage for building image
+# Use debian for easier build utilities
+FROM golang:1.19-bullseye AS build
+
+# Add non root user
+RUN useradd -u 1001 nonroot
+
+WORKDIR /app 
+
+# Copy only files required to install dependencies (better layer caching)
+COPY go.mod go.sum ./
+
+# Use cache mount to speed up install of existing dependencies
+RUN --mount=type=cache,target=/go/pkg/mod \
+  --mount=type=cache,target=/root/.cache/go-build \
+  go mod download
+
+COPY . .
+
+# Compile application during build rather than at runtime
+# Add flags to statically link binary
+RUN go build \
+  -ldflags="-linkmode external -extldflags -static" \
+  -o api-golang
+
+# Use separate stage for deployable image
+FROM scratch
+
+# Set gin mode
+ENV GIN_MODE=release
+
+WORKDIR /
+
+# Copy the passwd file
+COPY --from=build /etc/passwd /etc/passwd
+
+# Copy the binary from the build stage
+COPY --from=build /app/api-golang api-golang
+
+# Use nonroot user
+USER nonroot
+
+# Indicate expected port
+EXPOSE 8080
+
+CMD ["/api-golang"]