Logging and Debugging

Logging

Yoga uses 4 log levels debug, info, warn and error. By default, Yoga will only log info, warn and error messages.

Log Level Overview

`error`

Only log unexpected errors

`warn`

All prior log levels
deprecation notices

`info`

All prior log levels
Information about the current state of the system

`debug`

All prior log levels
Processing of GraphQL parameters
Parsing of GraphQL parameters
Execution or subscription start
Received GraphQL operation variables
Execution or subscription end
GraphiQL rendering
Health checks

Enabling Debug Logging

💡

Instead, on JavaScript environments that support environment variables via process.env (e.g. Node.js), you can also conditionally enable debug logging by setting the DEBUG environment variable to 1.

Custom log level

import { createYoga } from 'graphql-yoga'
import { createServer } from 'node:http'
import { schema } from './my-schema.js'
 
const yoga = createYoga({
  schema,
  logging: 'debug'
})

Change log level

You can customize the log lovel by passing on of the 4 levels to the logging option:

💡

We recommend not changing the default log level and only recommend changing it if you know what you are doing.

Custom log level

import { createYoga } from 'graphql-yoga'
import { createServer } from 'node:http'
import { schema } from './my-schema.js'
 
const yoga = createYoga({
  schema,
  logging: 'warn'
})

Specifying the log level of warn will only log warn and error messages being logged.

Custom logger

You can of course provide your own logger for piping to your favorite logging service/utility:

import { createYoga } from 'graphql-yoga'
import { createServer } from 'node:http'
import { schema } from './my-schema.js'
import { logger } from './my-logger.js'
 
const yoga = createYoga({
  schema,
  logging: {
    debug(...args) {
      logger.debug(...args)
    },
    info(...args) {
      logger.info(...args)
    },
    warn(...args) {
      logger.warn(...args)
    },
    error(...args) {
      logger.error(...args)
    }
  }
})
 
const server = createServer(yoga)
 
server.listen(4000, () => {
  console.info('Server is running on http://localhost:4000/graphql')
})

Further hook into the logging system by leveraging envelop's useLogger plugin:

import { createYoga, useLogger } from 'graphql-yoga'
import { createServer } from 'node:http'
import { schema } from './my-schema'
import { logger } from './my-logger'
 
const yoga = createYoga({
  schema,
  plugins: [
    useLogger({
      logFn: (eventName, args) => {
        // Event could be execute-start / execute-end / subscribe-start / subscribe-end / etc.
        // args will include the arguments passed to execute/subscribe (in case of "start" event) and additional result in case of "end" event.
        logger.debug(eventName, ...args)
      }
    })
  ]
})
 
const server = createServer(yoga)
 
server.listen(4000, () => {
  console.info('Server is running on http://localhost:4000/graphql')
})

Last updated on November 15, 2022

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