Docker-compose.yml is invalid

General
1

I’m getting the error regarding the docker-compose.yml file. here is my docker-compose.yml file
version: '3'
services:
app:
container_name: docer-node-mongo
restart: always
build: .
ports:
- '80:3000'
links:
- mongo
mongo:
container_name: mongo
image: mongo
port:
- '27017:27017'

the error is
ERROR: The Compose file ‘./docker-compose.yml’ is invalid because:
Unsupported config option for services.app: 'mongo’

2

Quite sure this is an error with the indenting, but we can’t find it if we don’t see the original formatting of your compose file.