Spring Cloud Config Client for NodeJS

Requires: NodeJS 10+

Feature requests are welcome.

Install

``sh
npm i cloud-config-client
`

Usage

`js
const client = require("cloud-config-client");
client.load({
application: "invoices"
}).then((config) => {
// Look for a key
const value1 = config.get("this.is.a.key");

// Using a prefix, this is equivalent to .get("this.is.another.key");
const value2 = config.get("this.is", "another.key");
});

// Or

const config = await client.load({ application: 'invoices' })
const value1 = config.get("this.is.a.key");

`

$3

Load implementation

#### Parameters

* options - Object, mandatory:
* endpoint string, optional, default=http://localhost:8888: Config server URL.
* rejectUnauthorized - boolean, optional, default = true: if false accepts self-signed certificates
* application - string, deprecated, use name: Load configuration for this application.
* name - string, mandatory: Load the configuration with this name.
* profiles string|string[], optional, default="default": Load profiles.
* label - string, optional: Load environment.
* auth - Object, optional: Basic Authentication for access config server (e.g.: { user: "username", pass: "password"}).
_endpoint_ accepts also basic auth (e.g. http://user:pass@localhost:8888).
* user - string, mandatory
* pass - string, mandatory
* agent - http.Agent|https.Agent, optional: Agent for the request. (e.g. use a proxy) (Since version 1.2.0)
* context - object, optional: Context for substitution (see context section below) (Since version 1.4.0)
* headers - object, optional: Additional request headers (Since version 1.5.0)
* callback - function(error: Error, config: Config), optional: node style callback. If missing, the method will return a promise.

`js
client.load(options)
.then((config) => { ... })
.catch((error) => { ... })

// or

client.load(options, (error, config) => { ... })

// or

async function foo () {
const config = await client.load(options)
//...
}

`

$3

Strings could contain context references, if a contexts is provided those references will be replaced by the actual values in the Config object reference.

YAML example:

`yaml
key01: Hello ${NAME:World}!!!
`

This is not related to spEl and those references are not an expression language.

Reference structure: ${CONTEXT_KEY:DEFAULT_VALUE?}:

* CONTEXT_KEY: Context key, if the value for the key is missing it will be use the default value or return the original string
* DEFAULT_VALUE: Optional default value

Environment variables as context:

`js
Client.load({
endpoint: 'http://server:8888',
name: 'application',
context: process.env })
.then(config => {
// config loaded
}).catch(console.error)
`

$3

Config class implementation

#### Properties

* raw: Spring raw response data.
* properties: computed properties as per Spring specification:
> Property keys in more specifically named files override those in application.properties or application.yml.

#### Methods

* get(...parts): Retrieve a value at a given path or undefined. Multiple parameters can be used to calculate the key.
* parts - string, variable, mandatory:
* forEach(callback, includeOverridden): Iterates over every key/value in the config.
* callback - function(key: string, value: string), mandatory: iteration callback.
* includeOverridden - boolean, optional, default=false: if true, include overridden keys or replace.

`js
config.get("this.is.a.key");
config.get("this.is", "a.key");
config.get("this", "is", "a", "key");

config.forEach((key, value) => console.log(key + ":" + value));
`

* toString(spaces): string: Returns a string representation of raw property.
* spaces - number, optional: spaces to use in format.
* toObject([options]): object: Returns the whole configuration as an object. (Since version 1.3.0).
* options.merge — specify strategy to process overlapping arrays:
* true — merge overlapping lists
* false — (default) use only the array from the most specific property source:

`js
// Simplified data from Spring Cloud Config:
// [
// {"key01[0]" : 5}, // ← the most specific property source
// {"key01[0]" : "string1", "key01[1]" : "string2"}
// ]

config.toObject({overlappingArrays:'merge'}) // {"key01[0]": 5, "key01[1]": "string2"}
config.toObject({overlappingArrays:'replace'}) // {"key01[0]": 5}
`


Behind a proxy

Example (adapted from https-proxy-agent site):

`js
const HttpsProxyAgent = require('https-proxy-agent')
const client = require('cloud-config-client')

const proxy = process.env.http_proxy || 'http://168.63.76.32:3128'
console.log('using proxy server %j', proxy)
const agent = new HttpsProxyAgent(proxy)

const options = {
application: 'demo',
profiles: ['test', 'timeout'],
agent
}
client.load(options).then((cfg) => {
console.log(cfg.get('test.users', 'multi.uid'))
console.log(cfg.toString(2))
}).catch((error) => console.error(error))
``

References

* Spring Cloud Config