Remix Datadog Express Tracing

Make better Datadog traces for Remix applications using Express.

Installation

pnpm

pnpm add remix-datadog-express-tracing

npm

npm install -S remix-datadog-express-tracing

Why this library?

When using Datadog for collecting telemetry from your backend services, one of the best features Datadog provides is distributed tracing.

While Datadog works out-of-the-box with many frameworks like Express, the route handler we have from Remix does not work properly due to being a catch-all handler when using an Express server.

This limits the ability of debugging on which URL pattern our request traces are hitting as everything will be marked under the / route in Datadog.

The Datadog team is aware about this (See this issue here) and while they are more invested in the NextJS ecosystem, there are no plans to prioritize Remix at the moment.

Dynamically enriching Datadog traces

To fix this, we must tap into the Datadog tracer hooks so we can enrich the trace with the http.route tag that will give us proper visibility on specific route patterns. By using this library we move out from this:

To this:

This renders in a substantial improvement given that we can narrow down issues to specific routes instead, facilitating debugging and improving the DX when using the Datadog tracing UI.

How to use this library

This library exposes a single registration callback that injects our own hooks to the Datadog tracer. This is not meant to be used in code and does not expose any public APIs.

Although, this library takes a single input:

• A generated routes file from the Remix CLI. During the build process, you can generate this file with:

pnpm exec remix routes --json >> ./build/remix_routes.json

Once this file is generated, you must define the following environment variable:

• REMIX_DD_ROUTE_FILE

export REMIX_DD_ROUTE_FILE="./build/remix_routes.json"

Now during your server startup script, you must call this with ESM only Node apps (as described here in the dd-trace docs) just after initializing the Datadog tracer with the following:

node --import dd-trace/register.js --import remix-datadog-express-tracing my_app.js

If you are starting up your app via Docker:

ENV REMIX_DD_ROUTE_FILE="./build/remix_routes.json"
CMD ["node", "--import", "dd-trace/register.js", "--import", "remix-datadog-express-tracing", "./build/express/index.js"]

Dependencies

This package depends on the following peer dependencies:

• [x] @remix-run/react compatible with version ^2
• [x] dd-trace compatible with version ^5