Fix error with CLI trying to select environment config for "basic configuration"

[galenandrew]

Issue

Per the docs for CLI knexfile.js, the following configuration should be supported:

Basic configuration:

module.exports = {
  client: 'pg',
  connection: process.env.DATABASE_URL || {
    user: 'me',
    database: 'my_app'
  }
};

Per the following conditional block in /src/bin/cli.js#L56-L59 (introduced in #527) there is no check to make sure config[environment] exists.

  if (environment) {
    console.log('Using environment:', chalk.magenta(environment));
    config = config[environment];
  }

This results in an undefined config when using the basic configuration.

Pull Request Details

This pull request includes:

• config assignment defaults to itself when config[environment] does not exist
• update to the docs indicating that NODE_ENV is also used to set the environment in Knex CLI
  (this was my issue originally…I did not know the CLI environment defaults to NODE_ENV)

NOTE: I branched off master, but after following the CONTRIBUTING guidelines other files in lib showed changes after building that my code would not have affected. My assumption is that the latest build in master was dirty so I have only included src changes in this PR.

[rhys-vdw]

Fixes #1103.

[rhys-vdw]

@galenandrew, thanks for the PR!

re #823:

This of course made the migrations and CLI work properly (although does not follow the docs), but then introduced the pooling error because the config object being passed into require('knex')(config) included the nested environment configs.

I'm thinking that Knex() might also accept a "non-basic" config (ie. { development: .., production: ...}) for complete parity between knexfile.js and Knex(). What do you think @galenandrew, @tgriesser?

[galenandrew]

@rhys-vdw I love that idea (updating Knex() to accept a non-basic config). What are your thoughts on having it fallback to looking for a knexfile if no config is passed into the Knex() constructor?

[rhys-vdw]

@galenandrew I considered that and think that it is probably not a good idea. I'd prefer for it to be supplied explicitly. IMO Knex() should create a connection-less QueryBuilder interface, rather than searching for a default connection silently. (Currently this is achieved by calling Knex({}).)

[galenandrew]

Ah…you make a good point.