Reliable HTTP get wrapper (cache and circuit breaker), best wrapped around things you dont trust very much.
Basic usage
var ReliableGet = require('reliable-get');
var config = {
cache:{
engine:'memorycache'
},
circuitbreaker:{
includePath: true
}
};
var rg = new ReliableGet();
rg.on('log', function(level, message, data) {
// Wire up to your favourite logger
});
rg.on('stat', function(type, key, value) {
// Wire up to your favourite stats library (e.g. statsd)
});
rg.get({url:'http://www.google.com'}, function(err, response) {
console.log(response.content);
});
Configuration options
When you create an instance of reliable-get you need to specify the cache and circuit breaker behaviour. This then applies across all requests.
var config = {
cache:{
engine:'redis',
url:'redis://localhost:6379?db=0'
},
circuitbreaker:{
windowDuration:5000,
numBuckets: 5,
errorThreshold: 20,
volumeThreshold: 3,
includePath: true
}
};
| Property | Description | Example / Default | Required |
|---|---|---|---|
| cache.engine | Cache to use, redis/memorycache/nocache | nocache | No |
| cache.engine.url | URL to redis | localhost:6379 | No |
| circuitbreaker.windowDuration | Window duration to collect errors over | 10000 | No |
| circuitbreaker.numBuckets | Number of segments within window | 10 | No |
| circuitbreaker.errorThreshold | Percentage of buckets in error before CB opens | 50 | No |
| circuitbreaker.volumeThreshold | Number of errored requests before CB opens | 10 | No |
To disable the circuit breaker, simply delete the circuitbreaker configuration.
GET options
When making a get request, you need to provide a basic options object:
rg.get({url:'http://www.google.com'}, function(err, response) {
console.log(response.content);
});
| Property | Description | Example / Default | Required |
|---|---|---|---|
| url | Service to get | http://my-service.tes.co.uk | Yes |
| timeout | Timeout for service | 5000 | No |
| cacheKey | Key to store cached value against | my-service_tes_co_uk | No |
| cacheTTL | TTL of cached value | 1 minute | No |
| explicitNoCache | Do not cache under any circumstances | false | No |
| headers | Headers to send with request | No | |
| tracer | Unique value to pass with request | No | |
| type | Type of request, used for statsd and logging | No | |
| statsdKey | Key that statsd events will be posted to | No | |
| eventHandler | Object (see below) for logging and stats | No |
Example from Compoxure backend request:
var options = {
url: targetUrl,
cacheKey: targetCacheKey,
cacheTTL: targetCacheTTL,
timeout: utils.timeToMillis(backend.timeout || DEFAULT_LOW_TIMEOUT),
headers: backendHeaders,
tracer: req.tracer,
statsdKey: 'backend_' + utils.urlToCacheKey(host)
};
From compoxure fragment request:
var options = {
url: url,
timeout: timeout,
cacheKey: cacheKey,
cacheTTL: cacheTTL,
explicitNoCache: explicitNoCache,
headers: optionsHeaders,
tracer: req.tracer,
statsdKey: statsdKey
}
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