Sentry Structured Logging for JavaScript (Browser/Node/Bun)

[AbhiPrasad]

Sentry is adding support for structured logs, so you can view and query your logs alongside your traces and errors—all in one place.

Note

To get early access to the Sentry logging product and to see how it works, see the announcement post.

To use the new Logging APIs to send application logs directly to Sentry, you'll have to upgrade to 9.12.0 of the JavaScript SDK or higher.

Logging is gated by an experimental option, _experiments.enableLogs.

Sentry.init({
  _experiments: {
    // Enable logs to be sent to Sentry.
    enableLogs: true,
  },
});

Then you can import and use methods from the Sentry.logger namespace to send logs to Sentry.

const { trace, debug, info, warn, error, fatal } = Sentry.logger;

trace('Starting database connection', { database: 'users' });
debug('Cache miss for user', { userId: 123 });
info('Updated profile', { profileId: 345 });
warn('Rate limit reached for endpoint', { endpoint: '/api/results/', isEnterprise: false });
error('Failed to process payment', { orderId: 'order_123', amount: 99.99 });
fatal('Database connection pool exhausted', { database: 'users', activeConnections: 100 });

You can leverage structured logging via the fmt helper. When you use fmt, the string template and parameters are sent separately so they can be queried independently in Sentry.

const { info, warn, fmt } = Sentry.logger;

info(fmt`Updated profile for user ${userId}`);
warn(fmt`Rate limit approaching for endpoint ${endpoint}. Requests: ${requests}, Limit: ${limit}`);

With server-side SDKs like @sentry/node, @sentry/bun or server-side of @sentry/nextjs or @sentry/sveltekit, you can do structured logging without needing the fmt helper function.

Sentry.logger.info('User %s logged in successfully', [123]);
Sentry.logger.warn('Failed to load user %s data', [123], { errorCode });

You can also configure the SDK to send logs via the JavaScript console object, using the SDK's consoleLoggingIntegration.

Sentry.init({
  // send console.log, console.error, and console.warn calls as logs to Sentry
  integrations: [Sentry.consoleLoggingIntegration({ levels: ['log', 'error', 'warn'] })],
});

In 9.13.0 and above of the JS SDK, we've added support to send logs via the winston logging library.

const winston = require('winston');
const Transport = require('winston-transport');

const transport = Sentry.createSentryWinstonTransport(Transport);

const logger = winston.createLogger({
  transports: [transport],
});

To filter logs, or update them before they are sent to Sentry, you can use the _experiments.beforeSendLog option.

Supported SDKs:

• @sentry/astro
• @sentry/aws-serverless
• @sentry/browser
• @sentry/bun
• @sentry/core
• @sentry/ember
• @sentry/gatsby
• @sentry/google-cloud-serverless
• @sentry/nestjs
• @sentry/nextjs
• @sentry/node
• @sentry/nuxt
• @sentry/react
• @sentry/remix
• @sentry/solid
• @sentry/solidstart
• @sentry/svelte
• @sentry/sveltekit
• @sentry/vercel-edge
• @sentry/vue

Important

@sentry/cloudflare and @sentry/deno currently do not have support for logging. This will be added in a future release of the SDK.

[zhiyan114]

There seems to be a typo with how fmt is used. The function is supposed to be called without a parenthesis. Ex: fmt`some ${format}`

[AbhiPrasad]

Good catch @zhiyan114 - fixed :)

[AbhiPrasad]

We’ve released 9.12.0 of the JS SDK which contains a variety of improvements and fixes for logging.

https://github.com/getsentry/sentry-javascript/releases/tag/9.12.0

We add a variety of new default attributes like server name for the backend sdks which should make debugging easier. We’ve also fixed a bug with how we were setting environment on logs.

For those who are using the node/bun sdks we’ve made improvements to the log buffering/flushing logic, which ensures we send logs more consistently and predictably.

Please upgrade and give it a try!

[AbhiPrasad]

We've released 9.13.0 of the JS SDK which contains support for the winston logging library.

const winston = require('winston');
const Transport = require('winston-transport');

const transport = Sentry.createSentryWinstonTransport(Transport);

const logger = winston.createLogger({
  transports: [transport],
});

https://github.com/getsentry/sentry-javascript/releases/tag/9.13.0

Please upgrade and give it a try!

[stefnnn]

Hey team Sentry. Promising product evolution for sure, we are eager to try to integrating our logs with our error reporting. We've been added to the pilot, upgraded to @sentry/nextjs@9.14.0 and @sentry/node@9.14.0 and added import * as Sentry from '@sentry/nextjs' to our central logging lib.

Now when we start the Next.js (15.2.3) frontend, we get an error Export logger doesn't exist in target module. I've traced this down to an import of Sentry.logger in our middleware.ts, where we log each incoming request. I'm slightly puzzled, as I assumed this code is only used server-side, but it looks like it's somehow imported into the clientside bundle at least in development.

Anything I should be trying differently? Here's a minimal repro: https://github.com/stefnnn/next-turbo-middleware

[alexanderjulmer]

I ran into a similar problem when I added a logger to the to the instrumentation.js outside of the if (process.env.NEXT_RUNTIME === "nodejs") {}. That seemed to run it also on the edge runtime which, as I understand it, has limited functionality and might not support the Sentry logger?

If correct, I would be interested in how to get any useful logging out of Sentry and Next.js such as your example of request logging. When active on a Next.js instance that merely serves a few React pages, it logs virtually nothing except the startup sequence.

[alexanderjulmer]

It's quite likely me, but I cannot get the integration to log anything with "@sentry/nextjs": "^9.14.0" and "next": "^15.3.1".

I included logging in my sentry.server.config.ts:

Sentry.init({
  integrations: [Sentry.consoleLoggingIntegration({ levels: ["log", "error", "warn"] }) ],
  _experiments: { enableLogs: true },
})

Then I included the Logger on a page:

import * as Sentry from "@sentry/nextjs"
import { Dashboard } from "@/app/dashboard/components/Dashboard.tsx"

export default async function DashboardPage() {
  Sentry.logger.info("Rendering Dashboard")
  return <Dashboard />
}