Docker-compose.yml is invalid: app.build contains an invalid type, it must be a string

Question

Running $ docker-compose up when I have docker-compose.yml as shown below, everything works as expected:

 app: build: . 

However, when I have docker-compose.yml as (which seems to be valid in docker-compose reference ):

 app: build: context: . 

I get the following error:

 $ docker-compose up ERROR: The Compose file './docker-compose.yml' is invalid because: app.build contains an invalid type, it should be a string 

I also tried context: "." without joy. Please help! Many thanks.

Answer 1

The format you are using is for Version 2 . You are currently using version 1 .

For version 1, Docker Compose expects a line:

 app: build: . 

For version 2, Docker Compose expects a string or object , but you must specify that your Docker Compose file is version 2:

 version: '2' services: app: build: context: .