test: Adding integration test using Relay benchmark (#2348)

Adding integration test using Relay benchmark

tests/integration/relay.Dockerfile

@@ -0,0 +1,48 @@
+# to build the test
+# docker build --pull -t relay-test -f ./relay.Dockerfile .
+# to run the test, start dragonfly locally with port 6379
+# then
+# docker run --network=host -t relay-test
+
+FROM linuxmintd/mint21.2-amd64
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update
+
+RUN add-apt-repository -y ppa:ondrej/php
+
+RUN apt-get install -y \
+  curl \
+  php-dev
+
+# Install Relay dependencies
+RUN apt-get install -y \
+  php-msgpack \
+  php-igbinary
+
+ARG RELAY=v0.6.8
+
+# Download Relay
+RUN PHP=$(php -r 'echo substr(PHP_VERSION, 0, 3);') \
+  && curl -L "https://builds.r2.relay.so/$RELAY/relay-$RELAY-php$PHP-debian-x86-64+libssl3.tar.gz" | tar xz --strip-components=1 -C /tmp
+
+# Copy relay.{so,ini}
+RUN cp "/tmp/relay.ini" $(php-config --ini-dir)/30-relay.ini \
+  && cp "/tmp/relay-pkg.so" $(php-config --extension-dir)/relay.so
+
+# Inject UUID
+RUN sed -i "s/00000000-0000-0000-0000-000000000000/$(cat /proc/sys/kernel/random/uuid)/" $(php-config --extension-dir)/relay.so
+
+# needed by the Relay benchmark
+RUN apt-get install -y composer php-curl
+
+# checkout relay benchmark
+RUN git clone https://github.com/cachewerk/relay.git
+
+WORKDIR relay
+RUN composer install
+
+WORKDIR benchmarks
+
+CMD ./run --filter '^(Relay)'