[Docker] Add docker file for SGL Router (#6915)

docker/Dockerfile.router

+######################## BASE IMAGE ##########################
+FROM ubuntu:24.04 AS base
+
+ARG PYTHON_VERSION=3.12
+
+# set the environment variables
+ENV PATH="/root/.local/bin:${PATH}"
+ENV DEBIAN_FRONTEND=noninteractive
+
+# uv environment variables
+ENV UV_HTTP_TIMEOUT=500
+ENV VIRTUAL_ENV="/opt/venv"
+ENV UV_PYTHON_INSTALL_DIR=/opt/uv/python
+ENV UV_LINK_MODE="copy"
+ENV PATH="$VIRTUAL_ENV/bin:$PATH"
+
+
+# install dependencies
+RUN echo 'tzdata tzdata/Areas select America' | debconf-set-selections \
+    && echo 'tzdata tzdata/Zones/America select Los_Angeles' | debconf-set-selections \
+    && apt update -y \
+    && apt install -y curl \
+    && rm -rf /var/lib/apt/lists/* \
+    && apt clean
+
+# install uv
+RUN curl -LsSf https://astral.sh/uv/install.sh | sh
+
+# install python
+RUN uv venv --python ${PYTHON_VERSION} --seed ${VIRTUAL_ENV}
+
+######################### BUILD IMAGE #########################
+FROM base AS build-image
+
+ARG SGLANG_REPO_REF=main
+
+# set the environment variables
+ENV PATH="/root/.cargo/bin:${PATH}"
+
+# install dependencies
+RUN apt update -y \
+    && apt install -y git build-essential libssl-dev pkg-config \
+    && rm -rf /var/lib/apt/lists/* \
+    && apt clean
+
+# install rustup from rustup.rs
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y \
+    && rustc --version && cargo --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}
+
+# working directory
+WORKDIR /opt/sglang/sgl-router
+
+# build the rust dependencies
+RUN cargo build --release \
+    && uv build \
+    && rm -rf /root/.cache
+
+######################### ROUTER IMAGE #########################
+FROM base AS router-image
+
+# Copy the built package from the build image
+COPY --from=build-image /opt/sglang/sgl-router/dist/*.whl dist/
+
+# Build the package and install
+RUN uv pip install --force-reinstall dist/*.whl
+
+# Clean up unnecessary files to reduce the image size
+RUN rm -rf /root/.cache \
+    && apt purge -y --auto-remove curl
+
+# Set the entrypoint to the main command
+ENTRYPOINT ["python3", "-m", "sglang_router.launch_router"]