optimize Dockerfile, and stage cache

tools/dockerfile/Dockerfile

@@ -1,26 +1,40 @@
-FROM --platform=$TARGETPLATFORM golang:1.22-bullseye as build
+ARG GO_VERSION=1.22
+ARG BASE_IMAGE="golang:${GO_VERSION}-bullseye"
+
+FROM --platform=$TARGETPLATFORM ${BASE_IMAGE} as build
 
 ENV PROJ_ROOT="/go/src/github.com/erda-project/erda-infra"
-COPY . "${PROJ_ROOT}"
 WORKDIR "${PROJ_ROOT}"
 
-ARG GOPROXY=https://goproxy.cn,direct
-RUN go env -w GO111MODULE=on && go env -w GOPROXY="${GOPROXY}"
+ENV GOPROXY=https://goproxy.cn,direct \
+    GO111MODULE=on \
+    CGO_ENABLED=0
+
+# Copy go.mod and go.sum to leverage Docker cache
+COPY go.mod go.sum ./
+RUN --mount=type=cache,target=/go/pkg/mod \
+    go mod download
+
+# Copy all project files
+COPY . .
+
+# Install goimports and gohub
 RUN go install golang.org/x/tools/cmd/goimports@latest
 
-RUN --mount=type=cache,target=/root/.cache/go-build\
+# Build gohub with cache mechanism
+RUN --mount=type=cache,target=/root/.cache/go-build \
     --mount=type=cache,target=/go/pkg/mod \
-    cd ./tools && \
-    go install ./gohub && \
+    go install ./tools/gohub && \
     gohub tools install --verbose --local
 
-
-FROM --platform=$TARGETPLATFORM golang:1.22-bullseye
+FROM --platform=$TARGETPLATFORM ${BASE_IMAGE}
 
 RUN go install golang.org/x/tools/cmd/goimports@latest
+
+# Copy built tools from build stage
 COPY --from=build /root/.gohub /root/.gohub
 COPY --from=build /go/bin/* /go/bin/
 
 WORKDIR /go
 
-CMD gohub
+CMD ["gohub"]