Spring-like Cloud Config for NodeJS Applications

NodeJS application configuration using similar style to Spring Config and using the Spring Cloud Config Server for remote property sources.

Depends on cloud-config-client for the config server client functionality.

Feature requests are welcome.

Introduction

You get to define your application properties the same way you do in your Spring Boot applications. Use a bootstrap.yml file to specify your config server settings and application.yml to hold your local application properties. This module even supports profiling, similar to Spring Boot profiles, giving you the option to define profile-based properties in either separate files, like application-{profile}.yml, or in a single multi-document yaml file using a profiles property on the applicable documents, like profiles: profile1,profile2.

Getting Started

Install the package

npm install spring-cloud-config

Define an application.yml, or a group of application.yml and application-{profile}.yml files, in the location of your choice.

application.yml

spring.cloud.config.name: my-application-name
db:
   mongo:
      url: http://localhost:27017
---
profiles: dev1,dev2
db:
   mongo:
      url: http://dev-mongo-server:27017

Define a bootstrap.yml in the location of your choice.

bootstrap.yml

spring:
   cloud:
      config:
         enabled: true
         endpoint: http://localhost:8888
         label: master
---
profiles: dev1,dev2
spring.cloud.config.endpoint: http://dev-config-server:8888

Load your configuration during startup/initialization.

const SpringCloudConfig = require('spring-cloud-config');

const configOptions = {
    configPath: __dirname + '/config',
    activeProfiles: ['dev1'],
    level: 'debug'
};
let myConfig;

SpringCloudConfig.load(configOptions).then(theConfig => {
   myConfig = theConfig;
   // now run your application with the loaded config props.
   // do this by saving the returned config object somewhere,
   // or by using the SpringCloudConfig.instance() helper.
);

Use the config later on in your code.

const SpringCloudConfig = require('spring-cloud-config');

const myConfig = SpringCloudConfig.instance();
console.log(`My Mongo DB URL: ${myConfig.db.mongo.url}`);

Using typescript? No problem...

import { Config, CloudConfigOptions, ConfigObject } from 'spring-cloud-config';

const cloudConfigOptions: CloudConfigOptions = {
    configPath: __dirname + '/config',
    activeProfiles: ['dev1'],
    level: 'debug'
};

let myConfig: ConfigObject;

Config.load(cloudConfigOptions).then((theConfig: ConfigObject) => {
   myConfig = theConfig;
   // now run your application with the loaded config props.
   // do this by saving the returned config object somewhere,
   // or by using the Config.instance() helper.
);

Now you can use the config properties later on.

import { Config } from 'spring-cloud-config';

console.log(`My Mongo DB URL: ${Config.instance().db.mongo.url}`);

Things Explained

The Yaml Files

As mentioned above, this module uses Yaml files to configure your application properties. You need to supply folder paths where it can expect to find two sets of files: bootstrap.yml and application.yml. The bootstrap yaml is used to configure your cloud config server properties, similar to Spring Cloud Config. The application yaml should be used for defining your application's configuration properties. Optionally, you can specify your application's name in application.yml instead of in bootstrap.yml, using the spring.cloud.config.name property. Doing so gives you the option of using a shared bootstrap.yml (i.e. shared with other apps) but still be able to specify your individual application's name.

Support for Profiles in Multi-Document Yaml

As with any Yaml implementation you can include multiple documents in a single Yaml file, using --- as a separator. Additionally, this module allows you to define documents that apply to specific 'profiles', same as the 'spring.profiles' concept. If you include a profiles property in a given yaml document, the properties in that document will only be included in your merged configuration result if any of the configOptions.activeProfiles match up with the specified profiles.

Example application.yml

spring.cloud.config.name: my-application-name
db:
   mongo:
      url: http://localhost:27017
---
profiles: dev1,dev2,!local
db:
   mongo:
      url: http://dev-mongo-server:27017

Applying Yaml Docs to Multiple Profiles

You can apply the properties of a Yaml doc to multiple application profiles. Just provide a comma separated string of profile names in the doc's profiles property, like profiles: dev1,dev2.

Excluding Yaml Docs from Profiles

This module supports the Not operator (!) on profiles to provide for excluding configuration properties from specific profiles. Just prepend an '!' to the profile name you want to exclude the given yaml doc from, like profiles: dev1,!dev2.

Support for Profile-Specific File Names

If your application supports a wide range of profiles and/or properties then you might consider using profile-specific file names for your application.yml. Wherever you keep your application.yml, just add more yaml files named with this pattern: application-{profile}.yml.

Examples

application.yml
application-local.yml
application-dev.yml
application-dev2.yml
application-prod.yml

Node Env Property Sources

This module provides some pre-defined properties/property sources from the Node env. This enables you to exclude sensitive data from your repository files and instead provide them using environment variables. For example, you might want to exclude the username and password used for authenticating with your remote config server from your git repo.

When set, node env variables will be mapped to their respective config properties during the bootstrap phase. Be aware, env variables take highest precedence so they'll override whatever value is provided from other sources.

Pre-Defined Env Variable Mappings

Remote Property Sources

If you enable the use of spring cloud config via the bootstrap property spring.cloud.config.enabled: true, the properties in application.yml will be overridden by any of the same properties defined in your remote sources. Keep in mind, however, any error encountered while reaching the remote property sources will be ignored, unless you set the bootstrap property spring.cloud.config.fail-fast: true. As a best practice, it is recommended that the properties defined in application.yml be kept up to date and represent the most current state of the application (as much as reasonably possible).

Cloud Config Client Fail Fast

If you need spring-cloud-config to throw an error when it can't reach the cloud config server, set the bootstrap property spring.cloud.config.fail-fast: true. Combine this with enabling retry (see below) to provide some resiliency to your cloud configuration retrieval.

Cloud Config Client Retry

If you'd like spring-cloud-config to retry connecting to your cloud config server after a failure, set the bootstrap property spring.cloud.config.retry.enabled: true, in addition to setting fail-fast to true (see above). When retry is enabled, spring-cloud-config will retry the config server connection based on the retry configuration you provide, or based on the default configuration. Below are the retry properties and their defaults. See the API specs further down for details.

• spring.cloud.config.retry.enabled: false
• spring.cloud.config.retry.max-attempts: 6
• spring.cloud.config.retry.max-interval: 1500 (ms)
• spring.cloud.config.retry.initial-interval: 1000 (ms)
• spring.cloud.config.retry.multiplier: 1.1

API

load function

Reads all defined property sources, including remote cloud config properties (if enabled), and returns the merged configuration properties object.

instance function

Returns the current configuration properties object. Use the load function prior to using this.

bootstrap.yml Cloud Config Options

application.yml Application Config Properties