print the commit that the interop docker image was build with

interop/Dockerfile

@@ -18,6 +18,7 @@ RUN git clone https://github.com/lucas-clemente/quic-go && \
 
 WORKDIR /quic-go
 
+RUN git rev-parse HEAD > commit.txt
 RUN go build -o server interop/server/main.go && \
  go build -o client interop/client/main.go
 
@@ -27,7 +28,7 @@ FROM martenseemann/quic-network-simulator-endpoint:latest
 WORKDIR /quic-go
 
 COPY --from=builder /quic-go/internal/testdata/cert.pem /quic-go/internal/testdata/priv.key internal/testdata/
-COPY --from=builder /quic-go/server /quic-go/client ./
+COPY --from=builder /quic-go/commit.txt /quic-go/server /quic-go/client ./
 
 COPY run_endpoint.sh .
 RUN chmod +x run_endpoint.sh

interop/run_endpoint.sh

@@ -4,6 +4,8 @@ set -e
 # Set up the routing needed for the simulation.
 /setup.sh
 
+echo "Using commit:" `cat commit.txt`
+
 if [ "$ROLE" == "client" ]; then
     # Wait for the simulator to start up.
     /wait-for-it.sh sim:57832 -s -t 10