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.
Contents
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:
This is the same as node-config files.
default.EXT
default-{instance}.EXT
{deployment}.EXT
{deployment}-{instance}.EXT
{short_hostname}.EXT
{short_hostname}-{instance}.EXT
{short_hostname}-{deployment}.EXT
{short_hostname}-{deployment}-{instance}.EXT
{full_hostname}.EXT
{full_hostname}-{instance}.EXT
{full_hostname}-{deployment}.EXT
{full_hostname}-{deployment}-{instance}.EXT
local.EXT
local-{instance}.EXT
local-{deployment}.EXT
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. Sojs
overridesyaml
, which overridesjson
. 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 theNODE_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 theNODE_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 presetconfig
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 theconfig
directory for config files. -
NODE_ENV
- By default, Confippet loadsdevelopment
config files after loadingdefault
. Set this environment variable to change to a different deployment, such asproduction
. -
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 withCONFIPPET
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 = {
foo: "bar"
};
const config = Confippet.loadConfig(options, defaults /* refresh: true */);
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 startupindex.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.
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