Implement #745: Ability to set default project name in YML

[fesor]

Added project section in docker compose file, which allows users to define default project name in their yaml files:

version: "2"
project:
    default_name: "example"

This will help teams not to forgot about that. For example in my company i have only 5 project, which uses docker compose, and I already experience some problems since developers sometime forgot to add custom project name.

Name resolution rules

• Use custom name from -p cli option if provided
• Use custom name from COMPOSE_NAME env variable if available
• Use default_name option from project section of yml fileif provided
• Use basename of project directory as project default name

Multiple compose files

If multiple compose yml files provided, project section will be used only from main one.

docker-compose.yml:

version: "2"
project:
    default_name: foo

docker-compose.override.yml:

version: 2
project:
    default_name: bar

If we start docker-compose as usual (i.e. docker-compose.override.yml will override service definition in main file), then project name will be foo.

But if we change the order of files:

docker-compose -f docker-compose.override.yml -f docker-compose.yml config

then bar will be used as project name.

[dnephin]

We discussed this a bit recently. Any project_name set in the Compose file should be just a default name, so it looks like the precendence order is correct in this PR. However, it's not clear from the name that it's only a "default", and not actually an override.

We weren't really able to come up with a good way to express this. Some ideas that have been suggested previously are:

• have a section called project: and make the key default_name: or default_project_name:
• make a top level key default_project_name:

I think it's going to be important to make it clear that this name is just a default.

[fesor]

@dnephin good point.

I think project section gives more space for future changes. In this case I more like default_name option.

version: "2"
project:
    default_name: "app"

What do you think?

[dnephin]

I personally like that option

ping @aanand , @shin-

[GordonTheTurtle]

Looks like we would not be able to merge this PR because of merge conflicts. Please rebase, fix conflicts, and force push to your branch.

[GordonTheTurtle]

Looks like we would not be able to merge this PR because of merge conflicts. Please rebase, fix conflicts, and force push to your branch.

[fesor]

Closing this in flavor of #3057

[adrianolek]

So was the idea of project name in yml abandoned? #3057 only allows to set project name via .env file.

[fesor]

@adrianolek well... my implementation doesn't allow to override default name from another docker-compose.yml which makes it just pointless, you could just specify project name in .env and that's do the trick.

Also all other cases that I looked to easily solves via env variables (personally I just specify all this in CI build/deploy job as ENV variables and it works for me). Allowing to override default project name using multiple compose file just creates a lot of edge cases and this should be discussed.