1 files changed, 14 insertions, 1 deletions
diff --git a/docker/Dockerfile b/docker/Dockerfile
index d212334844..c35da67a2a 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,3 +1,16 @@
+# Dockerfile to build the matrixdotorg/synapse docker images.
+#
+# To build the image, run `docker build` command from the root of the
+# synapse repository:
+#
+#    docker build -f docker/Dockerfile .
+#
+# There is an optional PYTHON_VERSION build argument which sets the
+# version of python to build against: for example:
+#
+#    docker build -f docker/Dockerfile --build-arg PYTHON_VERSION=3.6 .
+#
+
 ARG PYTHON_VERSION=2
 
 ###
@@ -59,6 +72,6 @@ COPY ./docker/conf /conf
 
 VOLUME ["/data"]
 
-EXPOSE 8008/tcp 8448/tcp
+EXPOSE 8008/tcp 8009/tcp 8448/tcp
 
 ENTRYPOINT ["/start.py"]