Connect exernal (mlab) service with docker-compose

I am trying to connect my external mlab service using docker-compose.yml file. Below is my code…

version: ‘3’
services:
prisma:
image: prismagraphql/prisma:1.22-beta
restart: always
ports:
- “4466:4466”
environment:
PRISMA_CONFIG: |
port: 4466
databases:
default:
connector: mongo
uri: mongodb://:@ds175840.mlab.com:75840/databsename
database: kocyn-gql

Please help me out if i’m doing anything wrong.Thanks