Multi-File Loader

A simple versatile Multi-file loader for ease of use or replacing environment variables.

Installation:

npm install multi-file-loader

Usage:

See example config files below for sources

Simple

Simple default sync usage

const { readConfig } = require('multi-file-loader')();
const myJsonConfig = readConfigSync('./myFile.json');
const myTextConfig = readConfigSync('./myFile.txt');

console.log(myJsonConfig.isJson); // Outputs true
console.log(myTextConfig); // contents of the text file.

Simple default usage

const { readConfig } = require('multi-file-loader')();
const myJsonConfig = await readConfig('./myFile.json');
const myTextConfig = await readConfig('./myFile.txt');

console.log(myJsonConfig.isJson); // Outputs true
console.log(myTextConfig); // Outputs contents of the myFile.txt file.

Advanced

Default behaviour can be modified by changing the parameters during instantiation:

// These are the default settings
const options = {
  errors: 'throw',
  logger: console,
  removeRead: true,
  defaultReturn: null,
  readOptions: 'utf8',
  forceJson: false,
  requireEnabled: true,
  errorCallback: null
};

// Then one of these 2 patterns:
const { readConfig } = require('multi-file-loader')(options);
// or
const MyConfig = require('multi-file-loader');
const { readConfig } = MyConfig(options);

Option definitions:

• errors: One of: 'throw', 'warn' or 'silent'.
• logger: The logger that should be called when errors is 'warn'
• removeRead: Deletes the file once read. Useful for when files are mounted in Kubernetes
• defaultReturn: If an error occurs, and errors is set to 'warn' or 'silent', this value will be returned.
• readOptions: Options for reading the file.
• forceJson: If true, will error if file doesn't parse to JSON and will return defaultReturn if errors is 'warn' or 'silent'. If false, will return data as is.
• requireEnabled: If false, will not attempt to load a file with require(). This may make some JSON files invalid, unless they follow strict JSON formatting rules.
• errorCallback: If this is a function, when any error occurs, this function will be called errorCallback(err) before logging or throwing.

Loading multiple files

Multiple files can be loaded asynchronously as arrays or objects. Files cannot be loaded synchronously.

Array

const { readConfig } = require('multi-file-loader')();
const myJsonConfig = await readConfig({ files: ['./myFile.json', './myOtherFile.json'] });

console.log(myJsonConfig[0].isJson); // Outputs true
console.log(myJsonConfig[1].someValue); // Outputs 1234

Object

const { readConfig } = require('multi-file-loader')();
const myConfigs = await readConfig({
  files: {
    myFile: './myFile.json',
    myOtherFile: './myOtherFile.json',
    myTextFile: './myFile.txt'
  }
});

console.log(myConfigs['myFile']?.isJson); // Outputs true
console.log(myConfigs['myOtherFile']?.someValue); // Outputs 1234
console.log(myConfigs['myTextFile']); // Outputs contents of the myFile.txt file.

Example files:

myFile.json

{
  isJson: true,
  DoesNotNeedJsonQuotes: true,
  "optionalQuotes": "Also true"
  // Also allows for comments
}

myOtherFile.json

{
  someValue: 1234
}

myFile.txt

IS_JSON: false
Can do whatever: also true

Kubernetes mounting secrets or Config-Maps as files

Check that your secret or config-map exists:

Secret:

kubectl get secrets -n my-namespace my-secret

Config-Map:

kubectl get configmap -n my-namespace my-configmap

Modify your pod or desployment's YAML, ensure that the file can be deleted after it is read (unless you set removeRead to false):

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
  namespace: my-namespace
spec:
  containers:
  - name: my-container
    image: my-image
    # Specify where the secret is mounted
    volumeMounts:
    - name: secret-volume
      mountPath: /path/to/secret.file
      readOnly: false
    - name: configmap-volume
      mountPath: /path/to/configmap.file
  volumes:
  # Specify the secret in volumes
  - name: secret-volume
    secret:
      secretName: my-secret
      # optional: true
  - name: configmap-volume
    configMap:
      name: my-configmap
      defaultMode: 432 # chmod 660.