Add v3.8 schema support

[aiordache]

Add v3.8 schema support

• Update version mappings
• Limit service scale to 'max_replicas_per_node'

$ cat docker-compose.yaml
version: "3.8"
services:
  test:
    image: nginx
    deploy:
      mode: replicated
      replicas: 3
      placement:
        max_replicas_per_node: 2

$ docker-compose --compatibility up -d
WARNING: Scale is limited to 2 ('max_replicas_per_node' field).
Creating network "schema_default" with the default driver
Creating schema_test_1 ... done
Creating schema_test_2 ... done

$ docker ps        
CONTAINER ID        IMAGE                 COMMAND                  CREATED              STATUS              PORTS                              NAMES
fc6510771d3a        nginx                 "nginx -g 'daemon of…"   41 seconds ago      Up 41 seconds       80/tcp                             schema_test_1
464e98b579f4        nginx                 "nginx -g 'daemon of…"   41 seconds ago      Up 41 seconds       80/tcp                             schema_test_2

Signed-off-by: Anca Iordache anca.iordache@docker.com

Resolves #6530

[rumpl]

LGTM

[ndeloof]

as both COMPOSEFILE_V3_7 and COMPOSEFILE_V3_8 == '1.38' doesn't this override API_VERSIONS['1.28'] just being set to '18.06.0' ?

[aiordache]

Yep, but I guess this mapping is more for us to easily view the minimum version needed for each compose file.

[ndeloof]

Maybe I misunderstand this constant, but afaik 3.8 do not add any new field to require an API upgrade vs 3.7, does it?

[aiordache]

Yes, I set it back to 1.38. This should be the minimum API version we need for the v3.8 schema.

[ulyssessouza]

LGTM