diff --git a/tools/dockerfile/grpc_ruby/Dockerfile b/tools/dockerfile/grpc_ruby/Dockerfile
index c84548c88028924c1309d574035d6a06750e1e44..47972e7effaa40f5c816a85e9309c09796283d4d 100644
--- a/tools/dockerfile/grpc_ruby/Dockerfile
+++ b/tools/dockerfile/grpc_ruby/Dockerfile
@@ -6,17 +6,19 @@ RUN cd /var/local/git/grpc \
   && git pull --recurse-submodules \
   && git submodule update --init --recursive
 
-# TODO: remove this, once make install is fixed
-RUN touch /var/local/git/grpc/include/grpc/support/string.h
-
 # Build the C core.
 RUN make install_c -C /var/local/git/grpc
 
 # Build ruby gRPC and run its tests
 RUN /bin/bash -l -c 'cd /var/local/git/grpc/src/ruby && bundle && rake'
 
-# Add a cacerts directory containing the Google root pem file, allowing the ruby client to access the production test instance
+# Add a cacerts directory containing the Google root pem file, allowing the
+# ruby client to access the production test instance
 ADD cacerts cacerts
 
-# Specify the default command such that the interop server runs on its known testing port
+# Add a service_account directory containing the auth creds file
+ADD service_account service_account
+
+# Specify the default command such that the interop server runs on its known
+# testing port
 CMD ["/bin/bash", "-l", "-c", "ruby /var/local/git/grpc/src/ruby/bin/interop/interop_server.rb --use_tls --port 8060"]