config-expander

Expands expressions in config files

example

file.js

import { expand } from "config-expander";

// expanding hole expressions at the value position (result key is a number)
expand({ key: "${value + 1}" }, { constants: { value: 77 } }).then(r =>
  console.log(JSON.stringify(r))
);

// calculate port numbers
expand({ constants: { base: 10000 }, http: { port: "${base + 1}" } }).then(r =>
  console.log(JSON.stringify(r))
);

// load config from file
expand("${include('tests/fixtures/other.json')}").then(r =>
  console.log(JSON.stringify(r))
);

Output

{ "key" : 78 }
{ "constants": { "base": 10000 }, "http": { "port": 10001 }}
{ "key": "value from other" }

Examples

read config file (json)

const configuration await expand("${include('" + '/path/to/the/config.json' + "')}")

load key file

{
  "ca": "${document(os.home + '/ca.pem')}"
}

calculate port numbers

{
  "http-port": "${base + 0}",
  "https-port": "${base + 1}"
}

conditions

{
  "copy-cmd": "${os.platform == 'win32' ? 'copy' : 'cp'}"
}

API

Table of Contents

• defaultConstants
  • Properties
• expand
  • Parameters
• Context
  • Properties
• Value
  • Properties
• Apply
  • Parameters
• ConfigFunction
  • Properties
• functions
  • include
    • Parameters
  • replace
    • Parameters
  • toUpperCase
    • Parameters
  • toLowerCase
    • Parameters
  • split
    • Parameters
  • encrypt
    • Parameters
  • decrypt
    • Parameters
  • spawn
    • Parameters
• merge
  • Parameters

defaultConstants

Predefined constants

Type: Object

Properties

• env Object environment variables from process.env
• os Object os module
• basedir string filesystem configuration start point

expand

Expands expressions in a configuration object

Parameters

• config Object config source

• options Object the options

  • options.constants Object additional constants
  • options.default Object default configuration
  • options.functions Object additional functions

Returns Promise<Object> resolves to the expanded configuration

Context

Type: Object

Properties

• constants Object

  • constants.basedir string
  • constants.env Object
  • constants.os string

• functions Object

Value

Type: Object

Properties

• type string
• value Object

Apply

Type: Function

Parameters

• context Context
• args Array<Value>

ConfigFunction

Type: Object

Properties

• arguments Array<string>
• returns string
• apply Apply

functions

knwon functions

include

Include definition form a file.

Parameters

• file string file name to be included

Returns string content of the file

replace

Replace string.

Parameters

• source string input value

Returns string replaced content

toUpperCase

Convert string into upper case.

Parameters

• source string input value

Returns string uppercase result

toLowerCase

Convert string into lower case.

Parameters

• source string input value

Returns string lowercase result

split

Split source string on pattern boundaries.

Parameters

• source string
• pattern string

Returns Array<string> separated source

encrypt

Encrypt a plaintext value.

Parameters

• key string
• plaintext string input value

Returns string encrypted value

decrypt

Decrypt a former encrypted string.

Parameters

• key string
• encrypted string

Returns string plaintext

spawn

Call executable.

Parameters

• executable string path
• arguments Array<string>
• options Object?

Returns string stdout

merge

merge from b into a When a and b are arrays of values only the none duplaces are appendend to a

Parameters

• a any
• b any

Returns any merged b into a

install

With npm do:

npm install config-expander

license

BSD-2-Clause