Logging

Monitor your Edge Functions with logging to track execution, debug issues, and optimize performance.

Logs are provided for each function invocation, locally and in hosted environments.

Accessing logs#

Production#

Access logs from the Functions section of your Dashboard:

Navigate to the Functions section of the Dashboard
Select your function from the list
Choose your log view:
- Invocations: Request/Response data including headers, body, status codes, and execution duration. Filter by date, time, or status code.
- Logs: Platform events, uncaught exceptions, and custom log messages. Filter by timestamp, level, or message content.

Function invocations.

Development#

When developing locally you will see error messages and console log statements printed to your local terminal window.

Log event types#

Automatic logs#

Your functions automatically capture several types of events:

Uncaught exceptions: Uncaught exceptions thrown by a function during execution are automatically logged. You can see the error message and stack trace in the Logs tool.
Custom log events: You can use console.log, console.error, and console.warn in your code to emit custom log events. These events also appear in the Logs tool.
Boot and Shutdown Logs: The Logs tool extends its coverage to include logs for the boot and shutdown of functions.

Custom logs#

You can add your own log messages using standard console methods:

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Deno.serve(async (req) => {
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  try {
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    const { name } = await req.json()
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    if (!name) {
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      // Log a warning message
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      console.warn('Empty name parameter received')
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    }
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    // Log a message
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    console.log(`Processing request for: ${name}`)
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    const data = {
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      message: `Hello ${name || 'Guest'}!`,
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    }
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    return new Response(JSON.stringify(data), {
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      headers: { 'Content-Type': 'application/json' },
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    })
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  } catch (error) {
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    // Log an error message
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    console.error(`Request processing failed: ${error.message}`)
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    return new Response(JSON.stringify({ error: 'Internal Server Error' }), {
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      status: 500,
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      headers: { 'Content-Type': 'application/json' },
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    })
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  }
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})

A custom log message can contain up to 10,000 characters. A function can log up to 100 events within a 10 second period.

Logging tips#

Logging request headers#

When debugging Edge Functions, a common mistake is to try to log headers to the developer console via code like this:

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// ❌ This doesn't work as expected
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Deno.serve(async (req) => {
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  console.log(`Headers: ${JSON.stringify(req.headers)}`) // Outputs: "{}"
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})

The req.headers object appears empty because Headers objects don't store data in enumerable JavaScript properties, making them opaque to JSON.stringify().

Instead, you have to convert headers to a plain object first, for example using Object.fromEntries.

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// ✅ This works correctly
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Deno.serve(async (req) => {
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  const headersObject = Object.fromEntries(req.headers)
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  const headersJson = JSON.stringify(headersObject, null, 2)
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  console.log(`Request headers:\n${headersJson}`)
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})

This results in something like:

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Request headers: {
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    "accept": "*/*",
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    "accept-encoding": "gzip",
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    "authorization": "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZSIsInJlZiI6InN1cGFuYWNobyIsInJvbGUiOiJhbm9uIiwieW91IjoidmVyeSBzbmVha3ksIGh1aD8iLCJpYXQiOjE2NTQ1NDA5MTYsImV4cCI6MTk3MDExNjkxNn0.cwBbk2tq-fUcKF1S0jVKkOAG2FIQSID7Jjvff5Do99Y",
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    "cdn-loop": "cloudflare; subreqs=1",
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    "cf-ew-via": "15",
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    "cf-ray": "8597a2fcc558a5d7-GRU",
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    "cf-visitor": "{\"scheme\":\"https\"}",
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    "cf-worker": "supabase.co",
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    "content-length": "20",
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    "content-type": "application/x-www-form-urlencoded",
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    "host": "edge-runtime.supabase.com",
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    "my-custom-header": "abcd",
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    "user-agent": "curl/8.4.0",
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    "x-deno-subhost": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiIsImtpZCI6InN1cGFiYXNlIn0.eyJkZXBsb3ltZW50X2lkIjoic3VwYW5hY2hvX2M1ZGQxMWFiLTFjYmUtNDA3NS1iNDAxLTY3ZTRlZGYxMjVjNV8wMDciLCJycGNfcm9vdCI6Imh0dHBzOi8vc3VwYWJhc2Utb3JpZ2luLmRlbm8uZGV2L3YwLyIsImV4cCI6MTcwODYxMDA4MiwiaWF0IjoxNzA4NjA5MTgyfQ.-fPid2kEeEM42QHxWeMxxv2lJHZRSkPL-EhSH0r_iV4",
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    "x-forwarded-host": "edge-runtime.supabase.com",
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    "x-forwarded-port": "443",
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    "x-forwarded-proto": "https"
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}