gcloud-trace

#### Preface

This is a simple, unofficial library for creating Stackdriver traces. Google
has an alpha library
that instruments a variety of common modules, which you may prefer to use
instead.

Authentication

If running on Google Cloud Platform, authentication can happen automatically
if you have the https://www.googleapis.com/auth/trace.append or https://www.googleapis.com/auth/cloud-platform
(a.k.a. cloud-platform) OAuth scope enabled on the resource where you're
running this library. Otherwise you will need to provide credentials:

``js
var projectId = process.env.GCLOUD_PROJECT; // e.g. 'grape-spaceship-123'

var tracing = require('gcloud-trace')({
projectId: projectId,

// The path to your key file:
keyFilename: '/path/to/keyfile.json'

// Or the contents of the key file:
credentials: require('./path/to/keyfile.json')
});
`

Example

`js
var config = {
projectId: 'my-project'
};
var tracing = require('gcloud-trace')(config);

function myfn(req, res, next) {
var span0 = tracing.startRootSpan('name'); // creates a trace and root-level span
// Do some work

// Optionally create nested spans with or without labels
var span1 = span0.startSpan('child span 1', {key1: 'value 1'});
// Do some work

var span2 = span1.startSpan('child span 1-1');
// Do some other work

span2.end(); // optional; if omitted will end when span1 or trace/span0 ends
span1.end(); // optional; if omitted will end when trace/span0 ends
span0.end(); // required
}
`

API

$3

#### require('gcloud-trace')(config)
* config.writeInterval Maximum write interval in seconds.
* config.maxBufferSize Maximum buffer size before a write is forced.
* Return: tracing instance.

#### tracing.startRootSpan(name[, labels])
* name Name for the span.
* labels