express-maintenance-mode
Express middleware that allows you to put the server(s) in maintenance mode
Table of Contents
Motivation
I developed this module because I needed an easy way to transfer all servers behind the load balancer to maintenance mode with one API request. That is why I made methods for getting and setting external maintenance status. In my production environment, I use these techniques to keep the service status in sync with Redis. This way, all servers in the load balancing group are aware of the status update within a minute.
How it works
Module provides simple api to control maintenance state. Access to all middlewares below can be controlled by maintenance middleware
Install
npm:
npm install express-maintenance-modeyarn:
yarn add express-maintenance-modeUsage
import { ExpressMaintenanceMode } from 'express-maintenance-mode';
const maintenance = new ExpressMaintenanceMode<MaintenanceResponseBody>({
maintenancePath: '/maintenance', // Path to control maintenance state
apiBasePath: '/api', // Base path of your API
accessKey: 'changeme', // Access key for maintenance endpoint. Works without authorization if not provided
getExternalMaintenanceState: () => {
// Optional
// Your method to get external state
},
setExternalMaintenanceState: () => {
// Optional
// Your method to set external state
},
localMaintenanceStateTTL: 6000 // Lifetime of local maintenance state, until it be synced with external state
});
// Optional
interface MaintenanceResponseBody {
message: string;
}
// App example
app.use(bodyParser.json());
app.use(maintenance.middleware)
// ...
app.use(yourGreatAPIRouter)
Redis example
import {MaintenanceState} from './index';
const getExternalMaintenanceState = async (): Promise<MaintenanceState<MaintenanceResponseBody>> => {
return yourRedisDAO.get<MaintenanceState<MaintenanceResponseBody>>('maintenance');
}
const setExternalState = async (maintenanceState: MaintenanceState<MaintenanceResponseBody>) => {
yourRedicDAO.save('maintenance', maintenanceState);
}API
To control maintenance status three methods available:
GET - to get maintenance status POST - to set server in maintenance mode DELETE - to set server in regular mode
Using POST method you can set response status code and body
Request body:
{
"statusCode": 503,
"body": {
"message": "Server in maintenance mode"
}
}
Contributors
| Name |
|---|
| George Lykuanov |
License
Apache-2.0 © George Lykuanov