Quote port mappings in docker-compose.yml

docker-compose.yml

@@ -4,14 +4,14 @@ services:
   postgres:
     image: postgres:9.5
     ports:
-      - 5432:5432
+      - "5432:5432"
     volumes:
       - postgres-volume:/var/lib/postgresql/data
 
   redis:
     image: redis:latest
     ports:
-      - 6379:6379
+      - "6379:6379"
     volumes:
       - redis-volume:/var/lib/redis/data
 
@@ -20,8 +20,8 @@ services:
     env_file:
       - '.env.sample'
     ports:
-      - 4567:4567
-      - 8080:8080
+      - "4567:4567"
+      - "8080:8080"
     depends_on:
       - redis
 
@@ -67,7 +67,7 @@ services:
       - slanger
       - seed_db
     ports:
-      - 3000:3000
+      - "3000:3000"
     volumes:
       - .:/app
       - gems:/gems