JarCasting |
|---|
| Retry a request with built-in exponential backoff. |
$ npm install --save request
$ npm install --save retry-request
var request = require('retry-request', {
request: require('request')
});
It should work the same as request in both callback mode and stream mode.
Note: This module only works when used as a readable stream, i.e. POST requests aren't supported (#3).
Do I need to install request?
Yes! You must independently install request and provide it to this library:
var request = require('retry-request', {
request: require('request')
});
The code will actually look for the request module automatically to save you this step. But, being explicit like in the example is also welcome.
Callback
urlThatReturns503 will be requested 3 total times before giving up and executing the callback.
request(urlThatReturns503, function (err, resp, body) {});
Stream
urlThatReturns503 will be requested 3 total times before giving up and emitting the response and complete event as usual.
request(urlThatReturns503)
.on('error', function () {})
.on('response', function () {})
.on('complete', function () {});
Can I monitor what retry-request is doing internally?
Yes! This project uses debug to provide the current retry attempt, each response status, and the delay computed until the next retry attempt is made. To enable the debug mode, set the environment variable DEBUG to retry-request.
(Thanks for the implementation, @yihaozhadan!)
request(requestOptions, [opts], [cb])
requestOptions
Passed directly to request. See the list of options supported: https://github.com/request/request/#requestoptions-callback.
opts (optional)
opts.noResponseRetries
Type: Number
Default: 2
The number of times to retry after a response fails to come through, such as a DNS resolution error or a socket hangup.
var opts = {
noResponseRetries: 0
};
request(url, opts, function (err, resp, body) {
// url was requested 1 time before giving up and
// executing this callback.
});
opts.objectMode
Type: Boolean
Default: false
Set to true if your custom opts.request function returns a stream in object mode.
opts.retries
Type: Number
Default: 2
var opts = {
retries: 4
};
request(urlThatReturns503, opts, function (err, resp, body) {
// urlThatReturns503 was requested a total of 5 times
// before giving up and executing this callback.
});
opts.currentRetryAttempt
Type: Number
Default: 0
var opts = {
currentRetryAttempt: 1
};
request(urlThatReturns503, opts, function (err, resp, body) {
// urlThatReturns503 was requested as if it already failed once.
});
opts.shouldRetryFn
Type: Function
Default: Returns true if http.incomingMessage.statusCode is < 200 or >= 400.
var opts = {
shouldRetryFn: function (incomingHttpMessage) {
return incomingHttpMessage.statusMessage !== 'OK';
}
};
request(urlThatReturnsNonOKStatusMessage, opts, function (err, resp, body) {
// urlThatReturnsNonOKStatusMessage was requested a
// total of 3 times, each time using `opts.shouldRetryFn`
// to decide if it should continue before giving up and
// executing this callback.
});
opts.request
Type: Function
Default: try { require('request') }
If we cannot locate request, we will throw an error advising you to provide it explicitly.
NOTE: If you override the request function, and it returns a stream in object mode, be sure to set opts.objectMode to true.
var originalRequest = require('request').defaults({
pool: {
maxSockets: Infinity
}
});
var opts = {
request: originalRequest
};
request(urlThatReturns503, opts, function (err, resp, body) {
// Your provided `originalRequest` instance was used.
});
cb (optional)
Passed directly to request. See the callback section: https://github.com/request/request/#requestoptions-callback.