http-close-channel

Express middleware for managing and closing HTTP channels. This middleware sends HTTP Connection Close headers to prompt the client to close the socket connection. This is useful for the following cases:

1. ensuring that HTTP traffic is evenly distributed across application replicas (e.g., even load distribution across pods in Kubernetes)
2. closing sockets during graceful shutdown

Middleware Options

The middleware takes the following options:

|option|type|description|default|from version| |------|----|-----------|-------|------------| |gracefulShutdown|Boolean|Enable closing sockets after the app receives a SIGTERM signal|false|1.0.0| |maxRequests|Integer|Set the number of requests per socket connection before the middleware will close the socket|100|1.0.0| |logger|Object|A logger object (see example below)|null no logging|1.0.0|

Example usage

The middleware can be added to an express app with the following steps...

1. include the package...

npm install http-close-channel --save

2. apply the middleware to the app...

// include the middleware
const httpCloseChannel = require('http-close-channel');

// create the app object
const app = express();

// add the middleware to the apps stack...
app.use(httpCloseChannel({
  maxRequests: 50,
  gracefulShutdown: true,
}));

Providing a logger

The middleware will make standard logging calls (e.g., logger.info(...), logger.warn(...)). This option has been tested with a bunyan logger. For example:

const bunyan = require('bunyan');

// create the app object
const app = express();

// create a bunyan based app logger
const loggerConfig = {
  name: 'k8s-test-utils',
  streams: [
    {
      level: 'debug',
      type: 'stream',
      stream: process.stdout,
    },
  ],
};
const appLogger = bunyan.createLogger(loggerConfig);

// pass the logger to the middleware
app.use(httpCloseChannel({
  logger: appLogger,
}));