Rename 3.4 schema to 3.4-beta

[shin-]

On the Docker Engine side, the 3.4 format is still in development until the 17.08 release. This change will let people use the current version using the 3.4-beta version marker.

Also adding the schema to docker-compose.spec, fixes #5128

[schmunk42]

@shin- How can I test 3.4-beta or better how do I get a nightly (static) binary of docker-compose?

Related: #2147

[shin-]

It's in 1.16.1, just use "3.4-beta" in the version field of your Compose file. Note that it will disappear in the next release though.

[schmunk42]

But it appears it does not support the x-[...] syntax from 3.4 mentioned in docker/cli#452

$ docker-compose -v
docker-compose version 1.16.1, build 6d1ac21

docker-compose.yml

version: '3.4-beta'
x-extends: &anchor
  - one
  - two
services:
  nginx:
    image: nginx

Error message

$ docker-compose config
ERROR: The Compose file './docker-compose.yml' is invalid because:
Additional properties are not allowed ('x-extends' was unexpected)

You might be seeing this error because you're using the wrong Compose file version. Either specify a supported version (e.g "2.2" or "3.3") and place your service definitions under the `services` key, or omit the `version` key and place your service definitions at the root of the file to use version 1.
For more on the Compose file format versions, see https://docs.docker.com/compose/compose-file/

[shin-]

Yes - it will be in regular 3.4 in the next release. #5140

[schmunk42]

I understand. But is there any chance to get nightly builds of binaries? #2147

[shin-]

@schmunk42 Yep, those should be up to date again, we checked with @dnephin this morning: https://dl.bintray.com/docker-compose/master/

[neumachen]

@shin I forget, but when is this going to be released?

[shin-]

Beginning of November