node-microsvc-lib

node-microsvc-lib

Installation

npm install node-microsvc-lib --save

Usage

Creating a microservice app:

// app.ts

import {Microservice, ConsoleLogger} from "node-microsvc-lib";

// factories/modules
import {RequestLogger} from "./factories/request_logger";
import {HealthCheck} from "./factories/health_check";
import {TestRestCtrl} from "./factories/rest_service";

// configs
import configs = require("./config/config");

const logger = new ConsoleLogger();

// create microservice appv
const app = new Microservice(configs, logger);

app.register_dependency("logger", logger);

app.register_factory("request_logger", RequestLogger);
app.register_factory("test_rest_ctrl", TestRestCtrl);
app.register_factory("health_check", HealthCheck);

process.on("uncaughtException", (err:Error)=>{
  logger.fatal(err);
});

app.init((err?: Error) => {
  if (err)
     return logger.error(err);

  logger.info("APP STARTED");
});

How configuration works

The Microservice instance expects a ServiceConfigs instance. This ServiceConfigs instance requires an instance of ServiceParams, an (optional) instance of IConfigsProvider and an instance of AppBaseConfigs

Three sets of configuration values exist:

• Parameters - that can be of type STRING, BOOL, INT_NUMBER or FLOAT_NUMBER;
• Feature Flags - always of boolean type;
• Secrets - always of string type.

ServiceConfigs (Required)

This is the object that the Microservice requires to source all its runtime configs.

ServiceParams (Required)

The definition of params, feature flags and secrets required by the service and their default values.

IConfigsProvider (Optional)

Optional instance that fetches all config values from an external service such as consul or hashicorp vault.

Load order / precedence

The order of loading:

• params.js file - ServiceParams instance gets loaded along with the default values;
• params.ENV_NAME.js file - the one that overrides values in ServiceParams per env - if LOCAL_OVERRIDES env var is set;
• IConfigsProvider - if a correspondent key name exists the value from the provider overrides the current one;
• Environment vars - all parameters can be overridden by passing an uppercase env var with the param key name

In summary, env vars always win (if defined).

Pre-requisites for contributing

NVM - Node Version Manager - https://github.com/creationix/nvm

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.34.0/install.sh | bash

After NVM is installed, execute this to download and install the correct node version:

nvm install 10.15.0