@evokegroup/aws-config

Configuration base class for AWS Lambda functions

Class: EvokeAwsConfig

constructor(event)

| Parameters | Type | Default | Description | | ---------- | ---- | ------- | ----------- | | event | EvokeAws.Event, object | | The event data passed to the Lambda function |

Usage

const EvokeAwsConfig = require('@evokegroup/aws-config');

class Config extends EvokeAwsConfig {
  site = null;
  environment = null;

  constructor(event) {
    super(event); 
    this.init();
  }
}

exports.handler = async (event) => {
  return new Promise((resolve, reject) => {
    const config = new Config(event);
    resolve({
      statusCode: 200
    });
  });
};

Properties

| Property | Type | Description | | -------- | ---- | ----------- | | event | EvokeAws.Event | The event data |

Methods

get(...args)

Get the value of a configuration property or a new object containing the specified properties and default values. If the property does not exist it will be added to the object using the default value or null.

| Parameters | Type | Default | Description | | ---------- | ---- | ------- | ----------- | | args[0] | object, Array<string>, string | | A string, Array<string> or object specifying the property/properties to return | | args[1] | any | | If args[0] is a string the default value to return. If args[1] is a function the value returned will result of that function. |

Usage

const EvokeAwsConfig = require('@evokegroup/aws-config');

// Simulate the setting of environment variables from Lambda
const env = Object.freeze({
  site: 'test.com',
  environment: 'dev',
  severity: 'error'
});
Object.keys(env).forEach((key) => {
  process.env[key] = env[key];
});

function parseSeverity(val) {
  if (val !== undefined && val !== null) {
    switch (val.toString().toLowerCase()) {
      case '0':
      case 'error':
        return 0;
      case '1':
      case 'debug':
        return 1;
      default:
        return -1;
    }
  } else {
    return -1;
  }
}

class Config extends EvokeAwsConfig {
  site = null;
  environment = null;
  severity = parseSeverity;

  constructor(event) {
    super(event);
    this.init();
  }
}

// Simulate the API Gateway sending in stage variables
const event = {
  stageVariables: {
    environment: 'stage'
  }
};

const config = new Config(event);

console.log(config.site); // Expected result (from process.env): 'test.com'
console.log(config.get('environment', 'dev')); // Expected result (overridden by the event.stageVariables): stage 
console.log(config.severity); // Expected result (from parseSeverity(process.env['severity'])): 0
console.log(config.doesNotExist); // Expected result: undefined
console.log(config.get('doesNotExist', 'abc123')); // Expected result: abc123
console.log(config.doesNotExist); // Expected result (doesNotExist was created during the above get call): abc123
console.log(config.get({
  site: null,
  environment: 'dev',
  severity: -1
})); // Expected result: { site: 'test.com', environment: 'stage', severity: 0 }
console.log(config.get(['site','environment'])); // Expected result: { site: 'test.com', environment: 'stage' }

init(config)

Initializes the EvokeAwsConfig instance.

| Parameters | Type | Default | Description | | ---------- | ---- | ------- | ----------- | | config | EvokeAwsConfig | this | The EvokeAwsConfig instance used during initialization. |

Usage

const EvokeAwsConfig = require('@evokegroup/aws-config');

// Simulate the setting of environment variables from Lambda
const env = Object.freeze({
  site: 'test.com',
  environment: 'dev'
});
Object.keys(env).forEach((key) => {
  process.env[key] = env[key];
});

const event = {};

// Preferred approach, declare a class
class Config extends EvokeAwsConfig {
  site = null;
  environment = null;

  constructor(event) {
    super(event);
    this.init();
  }
}
const config = new Config(event);

// Quick and dirty, probably fine for just a few properties or creating a config inline
const evokeAwsConfig = new EvokeAwsConfig(event);
evokeAwsConfig.init({
  site: null,
  environment: null
});

serialize()

Serializes the instance.