SkyWalking NodeJS Agent

SkyWalking-NodeJS: The NodeJS Agent for Apache SkyWalking, which provides the native tracing abilities for NodeJS backend project.

SkyWalking: an APM(application performance monitor) system, especially designed for microservices, cloud native and container-based (Docker, Kubernetes, Mesos) architectures.

Install SkyWalking NodeJS package from npmjs

$ npm install --save skywalking-backend-js

Set up NodeJS Agent

SkyWalking NodeJS SDK requires SkyWalking backend (OAP) 8.0+ and NodeJS >= 10.

import agent from 'skywalking-backend-js';

agent.start();

This will use default configurations to start the SkyWalking agent above, if you want to specify your own configurations, here are two methods.

• Pass those values to agent.start method, such as:

agent.start({
  serviceName: 'my-service-name',
  serviceInstance: 'my-service-instance-name',
  collectorAddress: 'my.collector.address:port',
});

Note that all options given (including empty/null values) will override the corresponding default values, e.g. agent.start({ collectorAddress: '' }) will override the default value of collectorAddress to empty string, causing errors like DNS resolution failed.

• Use environment variables.

The supported environment variables are as follows:

Note that the various ignore options like SW_IGNORE_SUFFIX, SW_TRACE_IGNORE_PATH and SW_HTTP_IGNORE_METHOD as well as endpoints which are not recorded due to exceeding SW_AGENT_MAX_BUFFER_SIZE all propagate their ignored status downstream to any other endpoints they may call. If that endpoint is running the Node Skywalking agent then regardless of its ignore settings it will not be recorded since its upstream parent was not recorded. This allows elimination of entire trees of endpoints you are not interested in as well as eliminating partial traces if a span in the chain is ignored but calls out to other endpopints which are recorded as children of ROOT instead of the actual parent.

Supported Libraries

There are some built-in plugins that support automatic instrumentation of NodeJS libraries, the complete lists are as follows:

Compatible Libraries

The following are packages that have been tested to some extent and are compatible because they work through the instrumentation of an underlying package:

Experimental Azure Functions Support

The plugin AzureHttpTriggerPlugin provides a wrapper function for an Azure Functions Javascript HttpTrigger endpoint. This is an http server endpoint and it must be instrumented manually currently. So far all other plugins tested work within the HttpTrigger and so a trace can pass through the Function and on to other endpoints called by the function. How much sense it makes to instrument an Azure Function which already lives in the cloud and has robust monitoring incorporated is a good question, but at the least this plugin will allow those endpoints to show up in a Skywalking trace.

Usage:

const {default: agent, AzureHttpTriggerPlugin} = require('skywalking-backend-js');

agent.start({ ... });

module.exports = AzureHttpTriggerPlugin.wrap(async function (context, req) {

  /* contents of http trigger function */

});

All that needs to be done is the actual trigger function needs to be wrapped with azureHttpTriggerPlugin.wrap(), whether that function is a default export or an explicitly named entryPoint or run or index.

Experimental AWS Lambda Functions Support

The plugins AWSLambdaTriggerPlugin, AWSLambdaGatewayAPIHTTP and AWSLambdaGatewayAPIREST provide a wrapper functions for AWS Lambda Functions endpoints. AWSLambdaTriggerPlugin is a generic wrapper plugin which should work with any kind of Lambda trigger but also stores the least amount of informations since it does not know anything about the incoming data format. For this reason this type of trigger also can not link back to the caller, but it can create a new segment which will be propagated to all downstream children, this starting its own trace. AWSLambdaGatewayAPIHTTP and AWSLambdaGatewayAPIREST are specific wrappers for Lambda functions triggered by the GatewayAPI HTTP or REST triggers. They have the advantage of knowing the incoming data format and can thus extract existing trace segment information from incoming requests and chain correctly from upstream to any downstream endpoints.

Usage:

const {default: agent, AWSLambdaGatewayAPIHTTP} = require('skywalking-backend-js');

agent.start({ ... });

exports.handler = AWSLambdaGatewayAPIHTTP.wrap(async function (event, context, callback) {

  /* contents of http trigger function */

});

This is similar to Azure Functions wrapping, just wrap your handler function with AWSLambdaTriggerPlugin.wrap() or AWSLambdaGatewayAPIHTTP.wrap() or AWSLambdaGatewayAPIREST.wrap(). One thing to note is that AWS freezes processes in between invocations of lambda functions so whether you are doing async or sync handler functions with callbacks, you should make sure everything you need to do finishes before returning control to AWS or calling the synchronous callback. These plugins take this into account and automatically flush the segment buffers before closing a trace span.

Contact Us

• Submit an issue by using [Nodejs] as title prefix.
• Mail list: dev@skywalking.apache.org. Mail to dev-subscribe@skywalking.apache.org, follow the reply to subscribe the mail list.
• Join skywalking channel at Apache Slack. If the link is not working, find the latest one at Apache INFRA WIKI.
• Twitter, ASFSkyWalking

License

Apache 2.0