toobusy-middleware
Middleware for express applications that checks if the process is taking too long to respond to requests. If so, it skips further requests until the server is able to properly handle them again, protecting the app from crashing during high load peaks.
This is just a wrapper for Lloyd Hilaiel's toobusy module, which is, in fact, the responsible for all the load-handling logic.
Usage
npm install --save toobusy-middleware
NOTE: There may be some issues getting toobusy
to work in Windows environments. If
that's your case and you just want to get it working for development, you can
make toobusy
an optionalDependency
in the package.json
and the middleware
will act as a noop
.
In your application:
var express = ;var toobusy = ; var app = ; app // Put toobusy as high as possible in your middleware stack ; var server = app; process;
Parameters
The middleware accepts two parameters:
-
handler
(optional): A function that will be called before sending any headers, allowing you to customize how the request is handled. Use this to call external services (bring more nodes up, notify someone, etc) or to override the default response sent to the user. -
options
(optional): Middleware's settings:-
maxLag
: Maximum time (in ms) the server can be behind before the process is considered to be overloaded. See [toobusy
's tunable parameters] maxlag for more info. -
message
: Message to be displayed/returned when the server is too busy to process the request. If it's an object or an array, the response will be sent as JSON. Otherwise, it's sent as'text/html'
. -
status
: HTTP status code to send when the server is too busy. Defaults to status code503
(Service Unavailable).
-
Examples
Uses default behavior.
app;
Simple customization:
app
Sending a JSON response instead of HTML:
app
Taking action during high load:
// Sends the default response after taking the required actionapp;
Overriding the default response:
app;
Using both handler and options:
{ ;} app;
License
This project is licensed under the MIT license. See the LICENSE
file for
more details.