electrode-confippet

Electrode Confippet

Confippet is a versatile, flexible utility for managing configurations of Node.js applications. It's simple to get started, and can be customized and extended to meet the needs of your app.

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Contents

• Features
• Getting Started
  • Installation
  • Basic Use
• Config Composition
• Environment Variables
• Using Templates
• Usage in Node Modules
• Customization

Features

• Simple - Confippet's presetConfig automatically composes a single config object from multiple files. For most applications, no further customization is necessary.
• Flexible - Supports JSON, YAML, and JavaScript config files.
• Powerful - Handles complex multi-instance enterprise deployments.

Getting Started

In this example, we'll create two config files: a default file that always loads, and a production file that loads only when the NODE_ENV environment variable is set to production. We'll then import those files into a standard Node.js app.

Installation

npm install electrode-confippet --save

Basic Use

Make a config/ directory inside the main app directory, and put the following into a file named default.json in that directory:

{
  "settings": {
    "db": {
      "host": "localhost",
      "port": 5432,
      "database": "clients"
    }
  }
}

Next, add another file called production.json to the config/ directory, with this content:

{
  "settings": {
    "db": {
      "host": "prod-db-server"
    }
  }
}

Finally, in our Node.js app, we can import Confippet and use the configuration we've created:

const config = require("electrode-confippet").config;
const db = config.$("settings.db");

In this example, default.json will be loaded in all environments, whereas production.json will be loaded only when the NODE_ENV environment variable is set to production. In that case, the value of host in the db object will be overwritten by the value in production.json.

Config Composition

Confippet's presetConfig composes together files in the config/ directory, in the following order:

1. default.EXT
2. default-{instance}.EXT
3. {deployment}.EXT
4. {deployment}-{instance}.EXT
5. {short_hostname}.EXT
6. {short_hostname}-{instance}.EXT
7. {short_hostname}-{deployment}.EXT
8. {short_hostname}-{deployment}-{instance}.EXT
9. {full_hostname}.EXT
10. {full_hostname}-{instance}.EXT
11. {full_hostname}-{deployment}.EXT
12. {full_hostname}-{deployment}-{instance}.EXT
13. local.EXT
14. local-{instance}.EXT
15. local-{deployment}.EXT
16. local-{deployment}-{instance}.EXT

Where:

• EXT can be any of ["json", "yaml", "js"]. Confippet will load all of them, in that order. Each time it finds a config file, the values in that file will be loaded and merged into the config store. So js overrides yaml, which overrides json. You can add handlers for other file types and change their loading order—see composeConfig for further details.
• {instance} is your app's instance string in multi-instance deployments (specified by the NODE_APP_INSTANCE environment variable).
• {short_hostname} is your server name up to the first dot.
• {full_hostname} is your whole server name.
• {deployment} is your deployment environment (specified by the NODE_ENV environment variable).

Overridden values are handled as follows:

• Objects are merged.
• Primitive values (string, boolean, number) are replaced.
• Arrays are replaced, unless the key starts with + and both the source and the target are arrays. In that case, the two arrays are joined together using Lodash's _.union method.

After Confippet loads all available configuration files, it will look for override JSON strings from the NODE_CONFIG and CONFIPPET* environment variables. See the next section for details.

Environment Variables

Confippet reads the following environment variables when composing a config store:

• AUTO_LOAD_CONFIG_OFF - If this is set, then Confippet will not automatically load any configuration into the preset config store. Confippet.config will be an empty store. This enables you to customize the config structure before loading.
• NODE_CONFIG_DIR - Set the directory to search for config files. By default, Confippet looks in the config directory for config files.
• NODE_ENV - By default, Confippet loads development config files after loading default. Set this environment variable to change to a different deployment, such as production.
• NODE_APP_INSTANCE - If your app is deployed to multiple instances, you can set this to load instance-specific configurations.
• AUTO_LOAD_CONFIG_PROCESS_OFF - By default, after composing the config from all sources, Confippet will use processConfig to process templates. You can set this environment variable to disable template processing.
• NODE_CONFIG - You can set this to a valid JSON string and Confippet will parse it to override the configuration.
• CONFIPPET* - Any environment variables that starts with CONFIPPET will be parsed as JSON strings to override the configuration.

Using Templates

Values in your config files can be templates, which will be resolved with a preset context. See processConfig for more information about how to use config value templates.

Usage in Node Modules

If you have a Node.js module that has its own configurations based on environment variables, like NODE_ENV, you can use Confippet to load config files for your module.

The example below will use the default compose options to compose configurations from the directory config under the script's directory (__dirname).

const Confippet = require("electrode-confippet");

const options = {
  dirs: [Path.join(__dirname, "config")],
  warnMissing: false,
  context: {
    deployment: process.env.NODE_ENV
  }
};

const defaults = Confippet.store();
defaults._$.compose(configOptions);

Customization

The composeConfig feature supports a fully customizable and extendable config structure. Even Confippet's own preset config structure can be extended, since it's composed using the same feature.

If you want to use the preset config, but add an extension handler or insert a source, you can turn off auto loading, and load it yourself with your own options.

NOTE: This has to happen before any other file accesses Confippet.config. You should do this in your startup index.js file.

For example:

process.env.AUTO_LOAD_CONFIG_OFF = true;

const JSON5 = require("json5");
const fs = require("fs");
const Confippet = require("electrode-confippet");
const config = Confippet.config;

const extHandlers = Confippet.extHandlers;
extHandlers.json5 = (fullF) => JSON5.parse(fs.readFileSync(fullF, "utf8"));

Confippet.presetConfig.load(config, {
  extSearch: ["json", "json5", "yaml", "js"],
  extHandlers,
  providers: {
    customConfig: {
      name: "{{env.CUSTOM_CONFIG_SOURCE}}",
      order: 300,
      type: Confippet.providerTypes.required
    }
  }
});

The above compose option adds a new provider that looks for a file named by the environment variable CUSTOM_CONFIG_SOURCE and will be loaded after all default sources are loaded (controlled by order).

It also adds a new extension handler, json5, to be loaded after json.

To further understand the _$ and the compose options, please see the documentation for store, composeConfig, and processConfig.