test(multiplayer): exercise compose supervisor drain

compose.allocated-smoke.yml

@@ -24,3 +24,33 @@ services:
         condition: service_healthy
     ports:
       - "18080:8080"
+
+  game-server:
+    build:
+      context: .
+      target: game-server
+    command:
+      - --drain-url=http://127.0.0.1:7780/drain
+      - --drain-token-env=COSMIC_CLASH_DRAIN_TOKEN
+      - --drain-grace=10s
+      - --
+      - /opt/cosmic-clash/CosmicClashServer.x86_64
+      - --port=31001
+      - --allocated-mode
+      - --match-id=compose-match
+      - --server-id=compose-server
+      - --playlist-version=casual
+      - --playlist=casual
+      - --client-build=build-1
+      - --assignment-expiry-unix=4102444800
+      - --server-image-digest=sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+      - --transport=enet
+      - --region=EU
+      - --join-authorisations-file=/run/cosmic-clash/join-roster.json
+      - --join-authorisations-key-file=/run/secrets/cosmic-clash/join-signing-key
+      - --readiness-port=7780
+    environment:
+      COSMIC_CLASH_DRAIN_TOKEN: compose-drain-token
+    volumes:
+      - ${COMPOSE_SMOKE_DIR:-/tmp/cosmic-clash-allocated-smoke}/join-roster.json:/run/cosmic-clash/join-roster.json:ro
+      - ${COMPOSE_SMOKE_DIR:-/tmp/cosmic-clash-allocated-smoke}/join-signing-key:/run/secrets/cosmic-clash/join-signing-key:ro