Axiom Logging library

The @axiomhq/logging package allows you to send structured logs to Axiom from any JavaScript application.

// lib/axiom/logger.ts
import axiomClient from '@/lib/axiom/axiom';
import { Logger, ConsoleTransport, AxiomJSTransport } from '@axiomhq/logging';

export const logger = new Logger({
  transports: [
    new AxiomJSTransport({
      axiom: axiomClient,
      dataset: process.env.AXIOM_DATASET!,
      axiomClient: 'my-app/1.0',
    }),
    new ConsoleTransport({ prettyPrint: true }),
  ],
});

logger.info('Hello World!');

AxiomJSTransport appends logging package usage to the Axiom client's X-Axiom-Client header. With the example above, requests use an X-Axiom-Client header like axiom-js/<version> axiom-logging/<version> my-app/1.0.

Schema validation

Logger can validate and type log fields using any validator that implements Standard Schema v1 (for example zod).

import { z } from 'zod';
import { Logger, ConsoleTransport } from '@axiomhq/logging';

const LogFieldsSchema = z
  .object({
    userId: z.string(),
    action: z.enum(['login', 'logout']),
  })
  .strict();

const logger = new Logger({
  transports: [new ConsoleTransport()],
  schema: LogFieldsSchema,
  onValidationError: (context) => {
    console.warn('Dropped invalid log', context.stage, context.reason, context.issues);
  },
});

logger.info('User action', { userId: '123', action: 'login' });

Invalid logs are dropped before transport delivery. schema validates input fields before formatters run, and outputSchema can validate the final formatted event:

const OutputSchema = z.object({
  eventName: z.string(),
  userId: z.string(),
});

const logger = new Logger({
  transports: [new ConsoleTransport()],
  schema: LogFieldsSchema,
  outputSchema: OutputSchema,
  formatters: [
    (event) => ({
      eventName: event.message,
      userId: event.fields.userId,
    }),
  ],
});

Unknown key behavior depends on your schema configuration:

• strict object schemas (like z.object(...).strict()) reject unknown keys
• non-strict schemas may allow them

logger.raw(...) bypasses schema validation.

Requirements

Node.js 20 or higher is required. Node.js 18 is no longer supported.

Install

npm install @axiomhq/js @axiomhq/logging

Documentation

For more information about how to set up and use the @axiomhq/logging package, see the axiom.co/docs/guides/javascript.

License

MIT