ut-config

Reusable configuration load and edit methods.

Starting

ut-config assumes the application is being run with a command like

node index {app} {method} {env}

or

UT_APP=server UT_METHOD=debug UT_ENV=dev node index

Configuration

In addition to using environment configuration files within the application filesystem, the following additional options are available, which will override the configuration

• Configuration file
• Command line parameters
• Environment variables

The algorithm of how these are applied is described in the rc package, here. This is adapted from rc package readme:

• command line arguments, parsed by minimist (e.g. --foo baz, also nested: --foo.bar=baz)
• environment variables prefixed with ut_${impl}_${env}_
  • or use "__" to indicate nested properties (e.g. ut_${impl}_${env}_foo__bar__baz => foo.bar.baz)
• if you passed an option --config file then from that file
• a local .ut_${impl}_${env}rc or the first found looking in ./ ../ ../../ ../../../ etc.
• $HOME/.ut_${impl}_${env}rc
• $HOME/.ut_${impl}_${env}/config
• $HOME/.config/ut_${impl}_${env}
• $HOME/.config/ut_${impl}_${env}/config
• /etc/ut_${impl}_${env}rc
• /etc/ut_${impl}_${env}/config
• the object taken from environment configuration file within {app} / UT_APP folder (dev.js[on], test.js[on], etc.)
• the object taken from method configuration file within {app} / UT_APP folder (debug.js[on], install.js[on])
• the object taken from common.js[on] configuration file within {app} / UT_APP folder

All configuration sources that were found will be flattened into one object, so that sources earlier in this list override later ones.

File based configuration sources outside the application folder can be in ini, json or yaml format.

${impl} is implementation identifier taken from environment configuration file, ${env} is the environment passed through command line or UT_ENV environment variable, or 'dev' (by default)

Environment configuration files

These files are part of the application and define the defaults for each environment. Environment configuration files can be either .json or .js file. If it is a .js file, it must export an object. If a file named common.js or common.json exists, it is used as a base object for all environments where the actual environment configuration is merged. When using .js file, more complex configuration is possible - like having functions or other objects, not supported by JSON. Minimal environment file dev.json may look like:

{
    "implementation": "impl-test",
    "service": "admin"
}

Templating

After all configurations have been loaded and merged into a common object it gets processed through a template engine. For more info check ut-function.template and in particular the provided recursive rendering functionalities.

E.g.

const obj = require('ut-config').load({
    config: {
        x: 'normal string',
        y: '${hello("Test1")}',
        z: '${hello(test)}'
    },
    context: {
        hello: who => 'Hello ' + who + ' !!!',
        test: 'Test2'
    }
});

// obj.y would be equal to 'Hello Test1 !!!'
// obj.z would be equal to 'Hello Test2 !!!'

Everything that is passed in the context object is accessible as a context in the config through the template engine.

The context is additionally enriched with encrypt and decrypt methods (this is only in case UT_MASTER_KEY is available as environment variable which is currently being set by Jenkins). So if you have the correct master key you can securely define encrypted passwords and other sensitive data in the config.

E.g.

/*
  note that the context is not mandatory if you need to use
  only the built-in encrypt/decrypt methods
*/
const obj = require('ut-config').load({
    config: {
        pass: '${decrypt("3569bf662a23fad6eb2069e09e8da490dff37a84e69a5eb82a1efecf9f8fcdb2")}'
    }
});