docker-compose.yml : Unsupported config option for services: 'jenkins'

docker-compose.yml : Unsupported config option for services: 'jenkins'

What is docker compose ? 

Compose is a tool for defining and running multi-container Docker applications. With Compose, you use a YAML file to configure your application's services.

Error:

While doing docker-compose up you'll hit with this error.
ERROR: The Compose file './docker-compose.yml' is invalid because:
Unsupported config option for services: 'jenkins'

Solution:

1. Add "version: '2' at the beginning of your compose file if you have not done so.
2. Update your docker to latest Version.