Add a stub Rust crate (#12595)

docker/Dockerfile

@@ -92,11 +92,20 @@ RUN \
     libxml++2.6-dev \
     libxslt1-dev \
     openssl \
-    rustc \
     zlib1g-dev \
     git \
+    curl \
     && rm -rf /var/lib/apt/lists/*
 
+
+# Install rust and ensure its in the PATH
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+RUN mkdir /rust /cargo
+
+RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable
+
 # To speed up rebuilds, install all of the dependencies before we copy over
 # the whole synapse project, so that this layer in the Docker cache can be
 # used while you develop on the source
@@ -108,8 +117,9 @@ RUN --mount=type=cache,target=/root/.cache/pip \
 
 # Copy over the rest of the synapse source code.
 COPY synapse /synapse/synapse/
+COPY rust /synapse/rust/
 # ... and what we need to `pip install`.
-COPY pyproject.toml README.rst /synapse/
+COPY pyproject.toml README.rst build_rust.py /synapse/
 
 # Repeat of earlier build argument declaration, as this is a new build stage.
 ARG TEST_ONLY_IGNORE_POETRY_LOCKFILE

docker/Dockerfile-dhvirtualenv

@@ -72,6 +72,7 @@ RUN apt-get update -qq -o Acquire::Languages=none \
     && env DEBIAN_FRONTEND=noninteractive apt-get install \
         -yqq --no-install-recommends -o Dpkg::Options::=--force-unsafe-io \
         build-essential \
+        curl \
         debhelper \
         devscripts \
         libsystemd-dev \
@@ -85,6 +86,15 @@ RUN apt-get update -qq -o Acquire::Languages=none \
         libpq-dev \
         xmlsec1
 
+# Install rust and ensure it's in the PATH
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+RUN mkdir /rust /cargo
+
+RUN curl -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path --default-toolchain stable
+
+
 COPY --from=builder /dh-virtualenv_1.2.2-1_all.deb /
 
 # install dhvirtualenv. Update the apt cache again first, in case we got a