Docker-compose - not able to expose port of container

I am not able to expose the port for zookeeper when I use the following yml file with docker-compose. The way I confirm is that container is running, but I cant telnet to port 2181. What could be wrong here?

image: jplock/zookeeper:3.4.5
- “2181:2181”

try to debug into the container.
docker exec -ti zookeeper_1 telnet localhost 2181
for example.

Does this work?