add dgraph backend to benchmark suite with safe type assertions for multi-backend support

cmd/benchmark/docker-compose-dgraph.yml

@@ -0,0 +1,44 @@
+version: "3.9"
+
+services:
+  dgraph-zero:
+    image: dgraph/dgraph:v23.1.0
+    container_name: orly-benchmark-dgraph-zero
+    working_dir: /data/zero
+    ports:
+      - "5080:5080"
+      - "6080:6080"
+    command: dgraph zero --my=dgraph-zero:5080
+    networks:
+      - orly-benchmark
+    healthcheck:
+      test: ["CMD", "sh", "-c", "dgraph version || exit 1"]
+      interval: 5s
+      timeout: 3s
+      retries: 3
+      start_period: 5s
+
+  dgraph-alpha:
+    image: dgraph/dgraph:v23.1.0
+    container_name: orly-benchmark-dgraph-alpha
+    working_dir: /data/alpha
+    ports:
+      - "8080:8080"
+      - "9080:9080"
+    command: dgraph alpha --my=dgraph-alpha:7080 --zero=dgraph-zero:5080 --security whitelist=0.0.0.0/0
+    networks:
+      - orly-benchmark
+    depends_on:
+      dgraph-zero:
+        condition: service_healthy
+    healthcheck:
+      test: ["CMD", "sh", "-c", "dgraph version || exit 1"]
+      interval: 5s
+      timeout: 3s
+      retries: 6
+      start_period: 10s
+
+networks:
+  orly-benchmark:
+    name: orly-benchmark-network
+    driver: bridge