Epsagon Tracing for Node.js frameworks

!Trace

This package provides tracing to Node.js applications for the collection of distributed tracing and performance metrics in Epsagon.

Contents

- Epsagon Tracing for Node.js frameworks
- Contents
- Installation
- Usage
- Auto-tracing
- Calling the SDK
- Tagging Traces
- Custom Errors
- Custom Warnings
- Filter Sensitive Data
- Ignore Endpoints
- Trace URL
- Frameworks
- Express
- Hapi
- Koa
- KafkaJS
- kafka-node
- PubSub
- SQS Consumer
- amqplib
- amqp
- bunnybus
- NATS
- HTTP Server
- WS (Websocket)
- Generic
- Integrations
- Configuration
- Getting Help
- Opening Issues
- License

Installation

To install Epsagon, simply run:
``sh
npm install epsagon-frameworks
`

Usage

$3

The simplest way to get started is to run your node command with the following environment variable:
`sh
export EPSAGON_TOKEN=
export EPSAGON_APP_NAME=
export EPSAGON_METADATA=FALSE
NODE_OPTIONS='-r epsagon-frameworks'
`

For example:
`sh
export EPSAGON_TOKEN=
export EPSAGON_APP_NAME=express-prod
export EPSAGON_METADATA=FALSE
NODE_OPTIONS='-r epsagon-frameworks' node app.js
`

You can see the list of supported frameworks

$3

Another simple alternative is to copy the snippet into your code:
`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

To run on your framework please refer to supported frameworks




$3

You can add custom tags to your traces, for easier filtering and aggregations.

Add the following call inside your code:
`javascript
epsagon.label('key', 'value');
epsagon.label('userId', userId);
`

In some frameworks tagging can be done in different ways.

$3

You can set a trace as an error (although handled correctly) to get an alert or just follow it on the dashboard.

Add the following call inside your code:
`javascript
try {
// something bad happens
} catch (err) {
epsagon.setError(err);
}

// Or manually specify Error object
epsagon.setError(Error('My custom error'));
`

$3

This API allows you to flag the trace with a warning and also enables more flexible alerting

Add the following call inside your code:
`javascript
try {
// something bad happens
} catch (err) {
epsagon.setWarning(err);
}

// Or manually specify Error object
epsagon.setWarning(Error('My custom error'));
`

In some frameworks custom errors can be declared in different ways.

$3

You can pass a list of sensitive properties and hostnames and they will be filtered out from the traces:

`javascript
epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
ignoredKeys: ['password', /.*_token$/],
urlPatternsToIgnore: ['example.com', 'auth.com'],
});
`

The ignoredKeys property can contain strings (will perform a loose match, so that First Name also matches first_name), regular expressions, and predicate functions.
Also, you can set urlPatternsToIgnore to ignore HTTP calls to specific domains.




$3

You can ignore certain incoming requests by specifying endpoints:
`javascript
epsagon.ignoreEndpoints(['/healthcheck'])
`

$3

You can get the Epsagon dashboard URL for the current trace, using the following:
`node


Inside some endpoint or function


console.log('Epsagon trace URL:', epsagon.getTraceUrl())
`

This can be useful to have an easy access the trace from different platforms.

Frameworks

The following frameworks are supported by Epsagon Frameworks.

|Framework |Supported Version |Epsagon Library |Auto-tracing Supported |
|----------------------------------------|---------------------------|---------------------------------------------------|-----------------------------------------------------|
|Express |>=3.0.0 |epsagon-frameworks |

• - [x]

|
|Hapi |>=17.0.0 |epsagon-frameworks |

• - [x]

|
|Koa |>=1.1.0 |epsagon-frameworks |

• - [x]

|
|restify |>=7.0.0 |epsagon-frameworks |

• - [x]

|
|fastify |>=3.0.0 |epsagon-frameworks |

• - [x]

|
|KafkaJS |>=1.2.0 |epsagon-frameworks |

• - [x]

|
|kafka-node |>=3.0.0 |epsagon-frameworks |

• - [x]

|
|PubSub |>=1.1.0 |epsagon-frameworks |

• - [x]

|
|SQS Consumer |>=4.0.0 |epsagon-frameworks |

• - [x]

|
|amqplib |>=0.5.0 |epsagon-frameworks |

• - [x]

|
|amqp |>=0.2.0 |epsagon-frameworks |

• - [x]

|
|bunnybus |>=7.0.0 |epsagon-frameworks |

• - [x]

|
|NATS |>=1.4.0 |epsagon-frameworks |

• - [x]

|
|HTTP Server |All |epsagon-frameworks |

• - [x]

|
|WS (Websocket) |>=7.3.1 |epsagon-frameworks |

• - [x]

|
|Generic |All |epsagon |

• - [ ]

|

$3

Tracing Express application can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the application is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
app.get('/', (req, res) => {
req.epsagon.label('key', 'value');
req.epsagon.setError(Error('My custom error'));
}
`

$3

Tracing Hapi application can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the application is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
server.route({
method: 'GET',
path:'/',
handler: (request, h) => {
request.epsagon.label('key', 'value');
request.epsagon.setError(Error('My custom error'));
}
});
`

$3

Tracing Koa application can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the application is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
app.use(async ctx => {
ctx.epsagon.label('key', 'value');
ctx.epsagon.setError(Error('My custom error'));
});
`

$3

Tracing restify application can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the application is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
function respond(req, res, next) {
req.epsagon.label('key', 'value');
req.epsagon.setError(Error('My custom error'));
}
`

$3

Tracing fastify application can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the application is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
fastify.get('/', (request, reply) => {
request.epsagon.label('key', 'value');
request.epsagon.setError(Error('My custom error'));
reply.send({ hello: 'world' })
})
`

$3

Tracing kafkajs consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
await consumer.run({
eachMessage: async ({ topic, partition, message }) => {
message.epsagon.label('key', 'value');
message.epsagon.setError(Error('My custom error'));
},
})
`

$3

Tracing kafka0node consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
consumer.on('message', function (message) {
message.epsagon.label('key', 'value');
message.epsagon.setError(Error('My custom error'));
})
`

$3

Tracing @google-cloud/pubsub consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
await consumer.run({
eachMessage: async ({ topic, partition, message }) => {
message.epsagon.label('key', 'value');
message.epsagon.setError(Error('My custom error'));
},
})
`

$3

Tracing sqs-consumer consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
const messageHandler = message => {
message.epsagon.label('key', 'value');
message.epsagon.setError(Error('My custom error'));
};
`

Or in batch message handler:
`javascript
const batchMessageHandler = messages => {
messages[0].epsagon.label('key', 'value');
messages[0].epsagon.setError(Error('My custom error'));
};
`

$3

Tracing amqplib consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
ch.consume(q, function cons(msg) {
if (msg !== null) {
msg.epsagon.label('key', 'value');
msg.epsagon.setError(Error('My custom error'));
ch.ack(msg);
}
});
`

$3

Tracing amqp consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
q.subscribe(function (message) {
message.epsagon.label('key', 'value');
message.epsagon.setError(Error('My custom error'));
console.log(message);
});
`

$3

Tracing bunnybus consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
// epsagon is added as an argument to the handler
handler: async ({message, metaData, ack, rej, requeue, epsagon}) => {
epsagon.label('key', 'value');
epsagon.setError(Error('My custom error'));
await ack();
}
`

$3

Tracing nats consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

$3

Tracing HTTP Server application can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces or setting custom errors can be by:

`javascript
const server = http.createServer((req, res) => {
epsagon.label('key', 'value');
epsagon.setError(Error('My custom error'));
});
`

$3

Tracing ws consumers can be done in two methods:
1. Auto-tracing using the environment variable.
2. Calling the SDK.

Calling the SDK is simple, and should be done in your main js file where the consumer is being initialized:

`javascript
const epsagon = require('epsagon-frameworks');

epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});
`

Tagging traces, setting custom errors/warnings or get current trace url can be by:

`javascript
socket.on('message', (message, epsagonSdk) => {
epsagonSdk.label('key', 'value');
epsagonSdk.setError(Error('My custom error'));
epsagonSdk.setWarning(Error('My custom warning'));
console.log('Epsagon trace URL:', epsagonSdk.getTraceUrl())
})
`

$3

For any tracing, you can simply use the generic Epsagon wrapper using the following example:

`javascript
const epsagon = require('epsagon');
epsagon.init({
token: 'epsagon-token',
appName: 'app-name-stage',
metadataOnly: false,
});


function main(params) {
// Your code is here
}

const wrappedMain = epsagon.nodeWrapper(main);
`

Integrations

Epsagon provides out-of-the-box instrumentation (tracing) for many popular frameworks and libraries.

|Library |Supported Version |
|--------------------|---------------------------|
|http |Fully supported |
|https |Fully supported |
|http2 |Fully supported |
|dns |Fully supported |
|aws-sdk |>=2.2.0 |
|amazon-dax-client |>=1.0.2 |
|@google-cloud |>=2.0.0 |
|@google-cloud/pubsub|>=1.1.0 |
|mysql |>=2 |
|mysql2 |>=1 |
|pg |>=4 |
|mongodb |>=2.2.12 |
|kafkajs |>=1.2.0 |
|kafka-node |>=3.0.0 |
|amqplib |>=0.5.0 |
|amqp |>=0.2.0 |
|redis |>=0.12.1 |
|ioredis |>=4.0.0 |
|mqtt |>=2.13.1 |
|nats |>=1.4.0 |
|openwhisk |>=3.0.0 |
|@azure/cosmos |>=3.7.5 |
|@azure/storage-blob |>=12.2.0 |
|ldapjs |>=2.1.0 |
|ws |>=7.3.1 |




Configuration

Advanced options can be configured as a parameter to the init() method or as environment variables.

|Parameter |Environment Variable |Type |Default |Description |
|-------------------|---------------------------|-------|-------------|-----------------------------------------------------------------------------------|
|token |EPSAGON_TOKEN |String |- |Epsagon account token |
|appName |EPSAGON_APP_NAME |String |Application|Application name that will be set for traces |
|metadataOnly |EPSAGON_METADATA |Boolean|true |Whether to send only the metadata (true) or also the payloads (false) |
|useSSL |EPSAGON_SSL |Boolean|true |Whether to send the traces over HTTPS SSL or not |
|traceCollectorURL |- |String |- |The address of the trace collector to send trace to |
|isEpsagonDisabled |DISABLE_EPSAGON |Boolean|false |A flag to completely disable Epsagon (can be used for tests or locally) |
|ignoredKeys |EPSAGON_IGNORED_KEYS |Array |- |Array of keys names (can be string or regex) to be removed from the trace |
|urlPatternsToIgnore|EPSAGON_URLS_TO_IGNORE |Array |[] |Array of URL patterns to ignore the calls |
|sendTimeout |EPSAGON_SEND_TIMEOUT_SEC |Float |0.2 |The timeout duration in seconds to send the traces to the trace collector |
|decodeHTTP |EPSAGON_DECODE_HTTP |Boolean|true |Whether to decode and decompress HTTP responses into the payload |
|httpErrorStatusCode|EPSAGON_HTTP_ERR_CODE |Integer|400 |The minimum number of an HTTP response status code to treat as an error |
|- |EPSAGON_AUTO_ADD_NODE_PATHS|Boolean |false |Auto add node_modules sub folders to look when patching libraries. |
|- |DISABLE_EPSAGON_PATCH |Boolean|false |Disable the library patching (instrumentation) |
|- |EPSAGON_DEBUG |Boolean|false |Enable debug prints for troubleshooting |
|- |EPSAGON_PROPAGATE_NATS_ID |Boolean|false |Whether to propagate a correlation ID in NATS.io calls for distributed tracing |
|- |EPSAGON_ADD_NODE_PATH |String |- |List of folders to looks for node_modules when patching libraries. Separated by :|
|- |EPSAGON_DNS_INSTRUMENTATION|Boolean|false |Whether to capture dns calls into the trace |
|- |EPSAGON_ALLOW_NO_ROUTE|Boolean|false |Whether to capture non-matched route requests in Express.js |
|- |EPSAGON_LOGGING_TRACING_ENABLED|Boolean|true` |whether to add an Epsagon ID to the logs in order to correlate traces to logs in the dashboard| |

Getting Help

If you have any issue around using the library or the product, please don't hesitate to:

* Use the documentation.
* Use the help widget inside the product.
* Open an issue in GitHub.

Opening Issues

If you encounter a bug with the Epsagon library for Node.js, we want to hear about it.

When opening a new issue, please provide as much information about the environment:
* Library version, Node.js runtime version, dependencies, etc.
* Snippet of the usage.
* A reproducible example can really help.

The GitHub issues are intended for bug reports and feature requests.
For help and questions about Epsagon, use the help widget inside the product.

License

Provided under the MIT license. See LICENSE for details.

Copyright 2020, Epsagon