RnR - runtime-node-refresh

RnR - is tiny lib to refresh node setup on runtime without restarting the node server.

Install

1npm install --save runtime-node-refresh

Usage

Following you will find example of simple project created via npm which uses runtime-node-refresh to refresh environment variable without running the node script again. Notice that the message to update environment variable came from other node process.

Create index.js file and add the following code:

1import RnR from 'runtime-node-refresh';
2
3process.env.LOG_LEVEL = 'error';
4
5RnR(() => {
6  process.env.LOG_LEVEL = 'debug';
7});
8
9setInterval(() => console.log(`The LOG_LEVEL is set to ${process.env.LOG_LEVEL}`), 3000);

Create `package.json' file and fill it with the following:

1  {
2    "name": "test-rnr",
3    "scripts": {
4      "start": "node index.js",
5      "refresh": "runtime-node-refresh"
6    },
7    "dependencies": {
8      "runtime-node-refresh": "^1.0.6"
9    }
10  }

Open two terminals, in the first terminal execute:

1npm start

Run the refresh task in the second terminal:

1npm run refresh

Back to first termiinal and see if the LOG_LEVEL variable value changed to debug.

Real life example:

It may be very usefult when you want to restart/update environment variable on running node application without restarting the node server. The real life example of RnR lib usage can be find in the following express based web-application: https://github.com/przemek-nowicki/node-express-template.ts/blob/master/src/core/utils/logger.ts#L2

Note: RnR is using node signals which means it does not work on Worker threads. It uses SIGPIPE signal to communicate between nodejs processes. By default the SIGPIPE is ignored by NodeJS. However it is recommend to check if you don't have a listener installed on SIGPIPE in your project before you use RnR library.