@mcf/provision-process
v0.2.2
Published
Provisions the process for a graceful termination.
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@mcf/provision-process
Provisions the process for a graceful termination.
Installation
npm i @mcf/provision-process;
OR
yarn add @mcf/provision-process;
Usage
Without middleware
provision-process
can be used to listen for SIGINT
and SIGTERM
operating system signals.
Example
const provisionProcess = require('@mcf/provision-process`);
// ...
// do the deed
provisionProcess();
With middleware
Use the function .addMiddleware()
to add methods which should run before the application terminates.
The .addMiddleware()
function accepts one parameter which should be a function that returns a Promise
. These Promises
will resolved just before the process exits. The .addMiddleware()
function is also chainable.
These middlewares should do things such as ensuring connection pools are closed, server being gracefully terminated, sending the correct responses to in-processing requests, and having nothing left in the Node event queue.
Example
const provisionProcess = require('@mcf/provision-process');
// fictitious database instance
const db = require('./path/to/db-instance');
// your logging module
const logger = require('./path/to/logger');
// fictitious server
const server = require('express')().listen();
provisionProcess
.addMiddleware(() => (new Promise((resolve, reject) => {
logger.info('closing database connections...');
db
.destroy()
.then((error) => {
if (error) {
reject(error);
} else {
resolve();
logger.info('database connections closed');
}
});
})))
.addMiddleware(() => (new Promise((resolve, reject) => {
logger.info('closing server gracefully...');
server
.close((error) => {
if (error) {
reject(error);
} else {
resolve();
logger.info('server closed');
}
});
})));
// do the deed
provisionProcess();
Note
To speed things up, the middlewares you add are executed in parallel. To execute things in sequential order, resolve your own promises and return the final result:
provisionProcess
.addMiddleware(() => (
(new Promise((resolve, reject) => {
// ...
})).then((result1) => {
return new Promise((resolve, reject) => {
// ...
})
}).then((result2) => {
return new Promise((resolve, reject) => {
// ...
})
})
));
Development
Installing Dependencies
Run the following from the root of the repository to initialise the dependencies since Lerna manages the dependencies for us across the multiple packages:
lerna bootstrap;
Running Tests
To run the tests during development, use:
npm run test-watch;
To run the tests on the built package, use:
npm run test;
Building
npm run build;
ChangeLog
0.1.0
- Initial release