Add async configuration support.

[wwalser]

Google Cloud's infrastructure doesn't inject metadata into the environment, instead, you have to call an outside service. Because of this, I need a migration solution that offers asynchronous configuration.

This, as I've discovered over the past five hours, is surprisingly difficult primarily because of a combination of:

1. Gulp doesn't support async configuration and doesn't plan to add it, see Gulp Issue 1505
2. The config helper API relies on state that is internal to the module and all calls assume the initialization of that state is synchronous.

To maintain existing behavior, this change takes care to initialize config at the start of all gulp tasks but waits until readConfig is called before logging anything or showing errors.

I'm happy to make the documentation changes if that would be helpful. Would you like this in this PR or a separate one?

[wwalser]

I believe I have the tests passing. I had to remove the {logging: false} option from readConfig. It was only used in one place, the version command.

I'm not sure why, but it was causing problems for a subset of tests. After removing the option, all tests pass.

[wwalser]

This passed for me, flaky tests? https://travis-ci.org/wwalser/cli/builds/163213992

[validkeys]

Perfect timing. I also need for fetching a decrypted key from an external key management store prior to loading my models.

[validkeys]

Any reason we're not merging this one? Would help me out a lot!

[wwalser]

I haven't added tests or documentation changes which I think would be reasonable requests by a maintainer before landing the PR. However, I'd like to get at least a nod from a maintainer to know that if I spend time on those, it will get landed.

Maybe I should mention them to get attention. Ping: @felixfbecker or @sdepold

[felixfbecker]

Im not a maintainer of the CLI :)

[wwalser]

Sry mate, I saw you active in the issues area and noticed "sequelize member" in the header of your comments. Do you know whose attention we should be trying to get perhaps?

Thanks :)

[wwalser]

One more try for @sdepold.

[wwalser]

Okay, trying a whole new crew. How about @Americas or @sushantdhiman?

[sushantdhiman]

Sorry for all this delay @wwalser , While this PR looks good to me generally but I am not familiar with sequelize/cli codebase. I will assign this issue to @sdepold and @Americas as they are more invloved with sequelize/cli maintenance

[Americas]

This PR LGTM too. And I can assure you I will merge this provided everything is good and has tests. You have our blessing 😛

[sdepold]

You have my entire trust. Go ahead @sushantdhiman :)

[wwalser]

I've added migrate and seed tests which use async configuration. Feel free to code review and land when appropriate.

I'd like to understand the NPM release schedule as well since I'm currently using my own branch of these changes in production.

[wwalser]

Would you like me to squash before you merge?

[sushantdhiman]

Github interface allow squashing so no need. @Americas will merge after review :)

[wwalser]

Ping @Americas

🎱

[wwalser]

ahem… may I get this PR landed for Christmas?

🎄🎄🎅🎅🎅🏽🎅🏽🎁🎁

[wwalser]

@sushantdhiman PR approved, tests written and passing. Please land.

Thanks!

[sushantdhiman]

Thanks for this PR @wwalser , Sorry for this delay