Add support for update order in compose deployments

[akalipetis]

Fixes #346

- What I did

Added support for the "order" key in the "update_config":

    deploy:
      replicas: 1
      update_config:
        parallelism: 1
        order: start-first | stop-first

- How I did it

Added the new key in the Compose V3.4 schema and hooked it with the implementation that already existed for service create/update.

- How to verify it

docker deploy -c docker-compose.yml demo

using this stack:

version: '3.4'

services:
  nginx:
    image: nginx:1.13.1-alpine
    deploy:
      replicas: 1
      update_config:
        parallelism: 1
        order: start-first
    ports:
      - 80:80

This will create a rolling update, even though we're just using 1 replica.

- Description for the changelog

Support for update_config.order: start-first | stop-first in Docker Compose version 3.4.

- A picture of a cute animal (not mandatory but encouraged)

[akalipetis]

/cc @dnephin I have cherry-picked da96115 and also included b882ab3 which (hopefully) rebuilds correctly the binary data.

This PR is based on #358

[dnephin]

Looks like CI is broken on this PR. We've been having problems with that on a few PRs

[dnephin]

Thanks!

There' also a "full test" in loader_test.go that I think should be updated to include this.

[akalipetis]

Thanks @dnephin - I'll definitely do that too. In regards to the CI, I thought it was because I had not included the -s flag in one commit and Gordon did not like me 😂

[codecov-io]

Codecov Report

Merging #360 into master will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #360      +/-   ##
==========================================
+ Coverage    46.2%   46.25%   +0.05%     
==========================================
  Files         193      193              
  Lines       16091    16092       +1     
==========================================
+ Hits         7435     7444       +9     
+ Misses       8269     8259      -10     
- Partials      387      389       +2

[akalipetis]

@dnephin added a full-example test, but I still have issues in the following tests:

• validate - I have changed to schema to include the order key, should I rollback this? This will crash the full example, since it needs v3.4 with order included to work
• lint - no idea really, when I open the logs they're stuck in the docker version step loading without ever showing anything...

[dnephin]

I think this might be why validate is failing. Do you have precommit hooks that remove this line?

[akalipetis]

Oh, I see. I'll fix this and update the PR. Thanks 👍

[akalipetis]

@dnephin seems like this was the issue after all 👍 - let me know if there's anything else you'd like me to do 😄

[dnephin]

I think you can remove the WIP from the title now.

Needs a rebase since we merged another PR which added the 3.4 schema. You can ignore the conflicts in bindata.go, just regenerate the file and add that.

Then squash your commits and this should be ready. You can drop the commit from me, it should already be in master.

[akalipetis]

Done 👌

[dnephin]

LGTM

[thaJeztah]

LGTM

[thaJeztah]

thanks!

[hairyhenderson]

@thaJeztah FYI this is missing in the docs for the update_config field: https://docs.docker.com/compose/compose-file/#update_config - I've logged an issue in the docs repo: docker/docs#5088

[thaJeztah]

@hairyhenderson oh, thanks for spotting that! Looks like I forgot checking for that 😅