109 lines
4.1 KiB
Markdown
109 lines
4.1 KiB
Markdown
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# OpenCensus Core Node.js
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[![Gitter chat][gitter-image]][gitter-url] ![Node Version][node-img] [![NPM Published Version][npm-img]][npm-url] ![dependencies Status][dependencies-status] ![devDependencies Status][devdependencies-status] ![Apache License][license-image]
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OpenCensus for Node.js is an implementation of OpenCensus, a toolkit for collecting application performance and behavior monitoring data. It currently includes 3 apis: stats, tracing and tags.
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The library is in alpha stage and the API is subject to change.
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## Installation
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Install the opencensus-core package with NPM:
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```bash
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npm install @opencensus/core
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```
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## Usage
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#### Get the global Stats manager instance.
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To enable metrics, we’ll import a few items from OpenCensus Core package.
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```javascript
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const { globalStats, MeasureUnit, AggregationType, TagMap } = require('@opencensus/core');
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// The latency in milliseconds
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const mLatencyMs = globalStats.createMeasureDouble(
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"repl/latency",
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MeasureUnit.MS,
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"The latency in milliseconds"
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);
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```
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#### Create Views and Tags:
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We now determine how our metrics will be organized by creating ```Views```. We will also create the variable needed to add extra text meta-data to our metrics – ```methodTagKey```, ```statusTagKey```, and ```errorTagKey```.
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```javascript
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const methodTagKey = { name: "method" };
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const statusTagKey = { name: "status" };
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const errorTagKey = { name: "error" };
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// Create & Register the view.
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const latencyView = globalStats.createView(
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"demo/latency",
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mLatencyMs,
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AggregationType.DISTRIBUTION,
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[methodTagKey, statusTagKey, errorTagKey],
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"The distribution of the latencies",
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// Bucket Boundaries:
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// [>=0ms, >=25ms, >=50ms, >=75ms, >=100ms, >=200ms, >=400ms, >=600ms, >=800ms, >=1s, >=2s, >=4s, >=6s]
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[0, 25, 50, 75, 100, 200, 400, 600, 800, 1000, 2000, 4000, 6000]
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);
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globalStats.registerView(latencyView);
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```
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#### Recording Metrics:
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Now we will record the desired metrics. To do so, we will use ```globalStats.record()``` and pass in measurements.
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```javascript
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const [_, startNanoseconds] = process.hrtime();
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const tags = new TagMap();
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tags.set(methodTagKey, { value: "REPL" });
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tags.set(statusTagKey, { value: "OK" });
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globalStats.record([{
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measure: mLatencyMs,
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value: sinceInMilliseconds(startNanoseconds)
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}], tags);
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function sinceInMilliseconds(startNanoseconds) {
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const [_, endNanoseconds] = process.hrtime();
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return (endNanoseconds - startNanoseconds) / 1e6;
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}
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```
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Measures can be of type `Int64` or `DOUBLE`, created by calling `createMeasureInt64` and `createMeasureDouble` respectively. Its units can be:
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| MeasureUnit | Usage |
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| ----------- | ----- |
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| `UNIT` | for general counts |
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| `BYTE` | bytes |
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| `KBYTE` | Kbytes |
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| `SEC` | seconds |
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| `MS` | millisecond |
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| `NS` | nanosecond |
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Views can have agregations of type `SUM`, `LAST_VALUE`, `COUNT` and `DISTRIBUTION`. To know more about Stats core concepts, please visit: [https://opencensus.io/core-concepts/metrics/](https://opencensus.io/core-concepts/metrics/)
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See [Quickstart/Metrics](https://opencensus.io/quickstart/nodejs/metrics/) for a full example of registering and collecting metrics.
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## Useful links
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- For more information on OpenCensus, visit: <https://opencensus.io/>
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- To checkout the OpenCensus for Node.js, visit: <https://github.com/census-instrumentation/opencensus-node>
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- For help or feedback on this project, join us on [gitter](https://gitter.im/census-instrumentation/Lobby)
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[gitter-image]: https://badges.gitter.im/census-instrumentation/lobby.svg
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[gitter-url]: https://gitter.im/census-instrumentation/lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge
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[npm-url]: https://www.npmjs.com/package/@opencensus/core
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[npm-img]: https://badge.fury.io/js/%40opencensus%2Fcore.svg
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[node-img]: https://img.shields.io/node/v/@opencensus/core.svg
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[license-image]: https://img.shields.io/badge/license-Apache_2.0-green.svg?style=flat
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[dependencies-status]: https://david-dm.org/census-instrumentation/opencensus-node/status.svg?path=packages/opencensus-core
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[devdependencies-status]:
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https://david-dm.org/census-instrumentation/opencensus-node/dev-status.svg?path=packages/opencensus-core
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## LICENSE
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Apache License 2.0
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