@appconfiger/core

idempotender core

This is the javascript library for fetching configurations from AWS AppConfig.

TODO: add timeout waiting for fetch app config

Usage

• npm install --save @appconfiger/core

• Create an AWS AppConfig configuration as in https://docs.aws.amazon.com/appconfig/latest/userguide/appconfig-working.html

Example: Check if feature flag is enabled

• Create function

import appconfiger from '@appconfiger/core';

const asession = await appconfiger({
  applicationId: "tifgo2h",
  configurationProfileId: "dy2ta4b",
  environmentId: "olevrb8",
  ttl: 300,
});

function sumNumbers(value1: number, value2 number): number {

  if(asession.featureFlagEnabled('use-new-strategy')) {
    console.log('This is the NEW strategy!');
    return value1 + value2;
  }

  console.log('This is the OLD strategy!');
  return value2 + value1;
}

Example: Get custom configuration contents

• This will make the function always add a certain value defined in the attributes of a feature flag as a configurable tweak to the summing function.

• Create function

import { startAppConfiger } from '@appconfiger/core';

const asession = await startAppConfiger({
  applicationId: "tifgo2h",
  configurationProfileId: "dy2ta4b",
  environmentId: "olevrb8",
  pollingInterval: 300,
});

function sumNumbers(value1: number, value2 number): number {
  const customTweaks = asession.featureFlag('custom-tweaks');
  if(customTweaks.enabled) {
    return value1 + value2 + customTweaks.alwaysAdd;
  }
  return value2 + value1;
}

Reference

• Config attributes:

  • applicationId

    • ApplicationIdentifier as in AWS AppConfig. Required

  • configurationProfileId

    • ConfigurationProfileIdentifier as in AWS AppConfig. Required

  • environmentId

    • EnvironmentId as in AWS AppConfig. Required

  • pollingInterval

    • Time in seconds for polling for new configuration updates

    • In the meanwhile a cached version of the configuration is returned

    • Defaults to 300

Functions

• featureFlag(name:string)

  • Returns the feature flag contents, or null, if it doesn't exist.

  • All feature flags have the attribute enabled and if you defined custom attributes to it, you can access them in the returned object.

• featureFlagEnabled(name:string)

  • Returns true if feature flag exists and is enabled.

  • Returns false if feature flag is disabled or if it doesn't exist.

• contents()

  • Returns the raw configuration profile contents with attribute contentType and configuration.

    • If contentType is "application/json", configuration attribute is automatically parsed to a javascript object

  • In case configurationProfileId is of type Feature Flag, it will return all feature flags along with all its attributes.

  • If its FreeForm, the raw contents will be returned (maybe a JSON object, yml or plain text).