Generate interop-related code in docker build
diff --git a/tools/dockerfile/grpc_php/Dockerfile b/tools/dockerfile/grpc_php/Dockerfile
index 0b48198..770d0d2 100644
--- a/tools/dockerfile/grpc_php/Dockerfile
+++ b/tools/dockerfile/grpc_php/Dockerfile
@@ -48,4 +48,6 @@
RUN cd /var/local/git/grpc/src/php && composer install
+RUN cd /var/local/git/grpc/src/php && protoc-gen-php -i tests/interop/ -o tests/interop/ tests/interop/test.proto
+
RUN cd /var/local/git/grpc/src/php && ./bin/run_tests.sh
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