[router] Add BRANCH_TYPE=local support to Dockerfile.router for local builds (#11571)

docker/Dockerfile.router

@@ -29,10 +29,14 @@ RUN curl -LsSf https://astral.sh/uv/install.sh | sh
 # install python
 RUN uv venv --python ${PYTHON_VERSION} --seed ${VIRTUAL_ENV}
 
+FROM scratch AS local_src
+COPY . /src
+
 ######################### BUILD IMAGE #########################
 FROM base AS build-image
 
 ARG SGLANG_REPO_REF=main
+ARG BRANCH_TYPE=remote
 
 # set the environment variables
 ENV PATH="/root/.cargo/bin:${PATH}"
@@ -47,17 +51,25 @@ RUN apt update -y \
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y \
     && rustc --version && cargo --version && protoc --version
 
-# pull the github repository
-RUN cd /opt \
-    && git clone --depth=1 https://github.com/sgl-project/sglang.git \
-    && cd /opt/sglang \
-    && git checkout ${SGLANG_REPO_REF}
+# pull the github repository or use local source
+COPY --from=local_src /src /tmp/local_src
+RUN if [ "$BRANCH_TYPE" = "local" ]; then \
+        cp -r /tmp/local_src /opt/sglang; \
+    else \
+        cd /opt \
+        && git clone --depth=1 https://github.com/sgl-project/sglang.git \
+        && cd /opt/sglang \
+        && git checkout ${SGLANG_REPO_REF}; \
+    fi \
+    && rm -rf /tmp/local_src
 
 # working directory
 WORKDIR /opt/sglang/sgl-router
 
 # build the rust dependencies
-RUN cargo build --release \
+RUN cargo clean \
+    && rm -rf dist/ \
+    && cargo build --release \
     && uv build \
     && rm -rf /root/.cache