+1 x 1000

As Astro adds more back-end features from actions to SSR configurable logging is a must-have feature because it is essential for any real-world business / enterprise applications.

A great example of a business-friendly Node framework that has great support for configurable logging is NestJS.

Check out the docs page for loggers and note how the expectation is that production applications will have specific logging requirements and will replace the built-in logger with their own. This is detailed in the last section "Use external logger": https://docs.nestjs.com/techniques/logger#use-external-logger

ALL logs coming from Astro must be wired through the logger including those from integrations. Just like NestJS, no log entry should be able to "slip by" and be emitted in an invalid format. NO logs by any official code or integration should be emitted using hardcoded console.log().

Consider the common use-case mentioned by the OP for structured logging in JSON format.

Custom loggers need to be supported to meet industry & compliance requirements such as data cleaning / scrubbing of sensitive fields as well as various business requirements.

When this requirement is met, developers can use log data to feed event buses + event streams, it can be dumped into log aggregation services where it can be made searchable / trigger notifications, and it can be dumped into storage buckets where it can be queried with Apache Parquet / AWS Athena. Structured data is easily analyzed by machine learning, etc. Ultimately this will enable Astro-based applications to fully "plug in" to a larger business or enterprise landscape and greater IT architecture.

For the record it is NOT an option to monkey patch console!

I've been looking into this. Are people more interested in build logs or SSR/runtime logs? Or both? What about dev?

Stage 1 RFC

Add support for configurable log handlers in Astro, allowing users to replace the default console output with custom logging implementations (e.g. structured JSON).

Background & Motivation

Users deploying Astro SSR to production need structured logging for integration with log aggregation services like Kibana, Logstash, CloudWatch, and Grafana/Loki. Agents running builds and dev locally work better with JSON. Today, Astro's logger is hardcoded – BaseApp uses consoleLogDestination which cannot be replaced, even by adapter authors. Error logs in rendering are split across multiple lines and formatted for human reading, making them unparseable by log aggregation tools.

This is a common requirement for any production SSR deployment and has been widely requested for a long time (this is currently the most upvoted feature request).

Goals

• Allow users to configure a custom log handler that receives all Astro log output
• Support structured logging (JSON) for production deployments out of the box
• Provide a --json CLI flag for zero-config JSON output (e.g. astro build --json, astro dev --json)
• Follow the established { entrypoint, config } factory pattern used by session drivers, font providers etc
• Work across all scopes: build, dev, and SSR runtime
• Ensure Vite logs flow through the custom handler (they already route through Astro's logger)
• Ship under experimental.logger initially

Non-Goals

• Request-scoped child loggers with correlation IDs
• Replacing the debug package integration – separate concern
• Separate handlers per scope (build vs server) – single handler with platform detection if needed

Example

Using a built-in handler:

// astro.config.mjs
import { defineConfig, logHandlers } from 'astro/config'

export default defineConfig({
  experimental: {
    logger: logHandlers.json({ pretty: false }),
  },
})

A third-party package like astro-pino-logger could export a helper function following the same pattern:

import { defineConfig } from 'astro/config'
import { pino } from 'astro-pino-logger'

export default defineConfig({
  experimental: {
    logger: pino({ destination: '/var/log/app.log' }),
    // returns: { entrypoint: 'astro-pino-logger/handler', config: { destination: '/var/log/app.log' } }
  },
})

CLI flag (no config needed):

astro build --json