Honeycomb NodeJS Magic

This package instruments your Express/NodeJS application for use with Honeycomb. Slice and dice requests by endpoint, status, or even User ID, with zero custom instrumentation required(1).

Requires Node 8+. Sign up for a Honeycomb trial to obtain a Write Key before starting.

Installation (Quick)

If you've got a NodeJS express app, you can get request-level instrumentation of Express and other packages you use, magically.

Start by installing this package:

npm install --save honeycomb-nodejs-magic

And adding this to the top of your app.js before require/importing of other packages:

require("honeycomb-nodejs-magic")({
  writeKey: "YOUR-WRITE-KEY"
  /* ... additional optional configuration ... */,
});

Configuration

The optional configuration above allows configuring global settings (Honeycomb credentials and dataset name) as well as per-instrumentation settings:

{
    writeKey: "/* your honeycomb write key, required */",
    dataset: "/* the name of the dataset you want to use (defaults to "nodejs") */"
    $instrumentationName: {
        /* instrumentation specific settings */
    }
}

Both writeKey and dataset can also be supplied in the environment, by setting HONEYCOMB_WRITEKEY and HONEYCOMB_DATASET, respectively.

For instrumentation settings, use the name of the instrumentation. For example, to add configuration options for express, your config object might look like:

{
    writeKey: "1234567890asbcdef",
    dataset: "my-express-server",
    express: {
        /* express-specific settings */
    }
}

For available configuration options per instrumentation, see the Instrumented packages section below.

Example questions

• Which of my app's requests are the slowest?
• Where's my app doing the most work / spending the most time?
• Which users are using the endpoint that I'd like to deprecate?
• Which XHR endpoints take the longest?

Example event

{
  "Timestamp": "2018-03-20T00:47:25.339Z",
  "express.baseUrl": "",
  "express.fresh": false,
  "express.hostname": "localhost",
  "express.http_version": "1.1",
  "express.ip": "127.0.0.1",
  "express.method": "POST",
  "express.originalUrl": "/checkValid",
  "express.path": "/checkValid",
  "express.protocol": "http",
  "express.query": "{}",
  "express.response_time_ms": 15.229326,
  "express.secure": false,
  "express.status_code": "200",
  "express.url": "/checkValid",
  "express.xhr": true,
  "meta.instrumentation_count": 4,
  "meta.instrumentations": "[\"child_process\",\"express\",\"http\",\"https\"]",
  "meta.request_id": "11ad83a2-ca8d-4918-9db2-27524456d9f7",
  "meta.type": "express"
}

Instrumented packages

The following is a list of packages we've added instrumentation for. Some actually add context to events, while others are only instrumented to enable context propagation (mostly the Promise-like packages.)

bluebird

Instrumented only for context propagation

express

Adds columns with prefix express.

Configuration options

Name	Type
express.userContext	Array<string>|Function<(request) => Object>

express.userContext

If the value of this option is an array, it's assumed to be an array of string field names of req.user. If a request has req.user, the named fields are extracted and added to events with column names of express.user.$fieldName.

For example:

If req.user is an object { id: 1, username: "toshok" } and your config settings include express: { userContext: ["username"] }, the following will be included in the express event sent to honeycomb:

express.user.username
toshok

If the value of this option is a function, it will be called on every request and passed the request as the sole argument. All key-values in the returned object will be added to the event. If the function returns a falsey value, no columns will be added. To replicate the above Array-based behavior, you could use the following config: express: { userContext: (req) => req.user && { username: req.user.username } }

This function isn't limited to using the request object, and can pull info from anywhere to enrich the data sent about the user.

http

Adds columns with prefix http.

https

Adds columns with prefix https.

mpromise

Instrumented only for context propagation

mysql2

Adds columns with prefix mysql2.

react-dom/server

Adds columns with prefix react.

sequelize

Instrumented only for context propagation

(if you'd like to see anything more here, please file an issue or 👍 one already filed!)

Adding additional context

The package instrumentations will send context to honeycomb about the actual requests and queries, but they can't automatically capture all context that you might want. If there's additional fields you'd like to include in events, you can use the customContext interface:

var honeyMagic = require("honeycomb-nodejs-magic")();

.
.
.

honeyMagic.customContext.add("extra", val);

This will cause an extra column (custom.extra) to be added to your dataset.

Troubleshooting

Use the DEBUG=honeycomb-magic:* environment variable to produce debug output.

---

Footnotes

1. For the currently limited set of supported packages, and only until you realize how powerful added custom instrumentation can make things :)