$ yarn add config-yml

or

$ npm install config-yml --save

Use config for yaml config files in Node.js projects. For example you might have a project with the following config.yml file in the project dir.

app:
    url: http://myapp.com/home
    cache: redis

db:
    location: mysql-db-prod

This config can be accessed like this.

const config = require('config-yml');

console.log(config.app.url);
console.log(config.app.cache);
console.log(config.db.location);

You can substitute variables in the config.yml like this.

dns: myapp.com

app:
    url: http://${dns}/home
    cache: redis

db:
    location: mysql-db-prod

This config would yield the following.

console.log(config.app.url);

// outputs - http://myapp.com/home

Instead of having a file named config.yml with all of your environment settings in place, you could have a config folder at the root level of your project. This module will read in every .yml file, and return an object that looks like:

{
    [file-name]: [parsed-file-contents],
    ...,
} 

if you need to do cross-file referencing, you can, via dot-notation:

# file `a.yml`
foo: bar

#file `b.yml`
baz: ${a.foo}

will get you

{
    a: {foo: 'bar'},
    b: {baz: 'bar'}
}

Based on an Environment ID, you can designate specific override settings for different types of environments. First you have to specify your Environment ID. You can do so in one of several ways. The first Environment ID that is found in the following order wins.

1. --env command line argument
2. --${static-environment} command line argument
3. ENVIRONMENT_ID process environment setting
4. git branch name with regex filtering

To understand this better let's first talk about Static Environments. These are environments that have their own environment specific settings or Environment Overrides. Not necessarily all environments have their own environment specific settings, but those that do should be defined as Static Environments in the config.yml as follows:

environments:
    static:
        - dev
        - test
        - prod

The other approach you can take is to have top level keys that only consist of your environments.

setup your config.yml as follows:

dev:
    # ...
test:
    # ...
prod:
    # ...

Your filenames determine the keys, so your directory could be set as follows:

config/dev.yml
config/test.yml
config/prod.yml

Set the Environment ID using the load function.

const config = require('config-yml').load('myenvironment')

Set the Environment ID using --env command line argument.

node app.js --env feature-xyz

This is often helpful when running gulp tasks.

gulp deploy --env feature-xyz

For Static Environments set the Environment ID using the static environment id as an argument.

gulp deploy --prod

Set the Environment ID using ENVIRONMENT_ID process environment variable.

export ENVIRONMENT_ID=feature-xyz

If an Environment ID is not found using one of the other methods, it will use the git branch for the current project folder. This branch can be filtered using regex. Let's say your current branch is Features/ISSUE-123-feature-xyz, and you have the following setting in your config.yml.

branchRegex: Features/ISSUE-\d+-((\w|-)+)

The Environment ID will be feature-zyz. If no branchRegex is given the branch name will be taken as is.

The Environment ID can be substituted into the config.yml. Let's say you have an Environment ID feature-xyz and the following config.yml.

dns: ${envId}.myapp.com

app:
    url: http://${dns}/home
    cache: redis

db:
    location: MYSQL-DB-${ENVID}

This will yield the following:

const config = require('config-yml');

console.log(config.dns);          // feature-xyz.myapp.com
console.log(config.app.url);      // http://feature-xyz.myapp.com
console.log(config.db.location);  // MYSQL-DB-FEATURE-XYZ

For Static Environments, settings can be overridden for that specific environment. For example, with the following config.yml:

dns: ${envId}.myapp.com

app:
    url: http://${dns}/home
    cache: redis

db:
    location: MYSQL-DB-${ENVID}

prod:
    app:
        url: https://${dns}
    db:
        location: DB-${ENVID}

and the following app.js file:

const config = require('config-yml');

console.log(config.dns);
console.log(config.app.url);
console.log(config.app.cache);
console.log(config.db.location);

the following command:

node app.js --prod

would output the following:

prod.myapp.com
https://prod.myapp.com
redis
MYSQL-DB-PROD