Edit

Retrieving Config

Overview

Your application would often have a dynamic behaviour that you would like to externally. This can be a config you store in S3, or in a simple case, stored as an environment variable.

Retrieving configuration from S3

Retrieving a JSON configuration is can be done easily in Laconia with the event package. You don't have to worry about hitting the S3 bucket and JSON parsing it:

/**
 * Lambda Environment variables:
 * - LACONIA_CONFIG_MY_CONFIG: s3:mybucket/dir/config.json
 */
const config = require("@laconia/config");
const laconia = require("@laconia/core");

// By convention, the name of the variable `myConfig` is derived by
// the environment variable name `LACONIA_CONFIG_MY_CONFIG`
const app = async (input, { myConfig }) => {
  console.log(myConfig); // Parsed JSON from S3 printed to the console
};

exports.handler = laconia(app).register(config.envVarInstances());

Retrieving boolean from environment variable

Sometimes developers forget that the value they're retrieving from an environment variable is actually a string, leading to wrong equality check. Laconia provides a simple conversion to make sure that the type injected is of boolean type.

/**
 * Lambda Environment variables:
 * - LACONIA_CONFIG_MY_FEATURE_TOGGLE: false
 */
const config = require("@laconia/config");
const laconia = require("@laconia/core");

// false will be injected
const app = async (input, { myFeatureToggle }) => {
  /* logic */
};

exports.handler = laconia(app).register(config.envVarInstances());
← Retrieving SecretsWarming Up →