What is the actual Compose version of a file if I do not specify a minor version?

General Discussions
1

I know I can use a specific major/minor version in my compose file (version: "3.6"), but what happens if I do not specify the minor version (version: "3")? Does this behave as “3.0”, the latest Compose version installed, or the highest Compose file format that supports the Docker Engine that I have installed?

Say, for sake of example, I have

  • Highest installed Compose version is 3.5
  • Docker Engine 17.06.0 installed

and I start my Compose file with version: "3". What feature set do I have access to? 3.0, 3.3, 3.5, or 3.6?

This is cross posted at SuperUser.com.

2

You have access to 3.0. You can verify this by running docker-compose config on a file with version: '3'.