wait-for-docker-composed-mongo.sh

#!/bin/bash

# Lets assume the service is called mongo

MONGO_CONTAINER_ID=''
# Iterate until container id gets defined
while [[ $MONGO_CONTAINER_ID == '' ]]; do
  echo "Waiting for container id"
  # Attempt to get the mongo container id once
  # docker-compose is supposed yo be running
  MONGO_CONTAINER_ID=`docker-compose ps -q mongo`
done

# Attempt to check the /var/log/mongodb.log
# file to evaluate whether mongo is ready to
# receive connections or not. This will repeat
# until the command succeds
until docker exec -itd $MONGO_CONTAINER_ID grep -q 'waiting for connections on port' /var/log/mongodb.log; do
  echo "Waiting for container to be up"
  sleep 0.1
done

# Now run your command here that depends on mongo
# container to be ready to connect
echo "This command depends on mongo receiving connections"