Self-Hosted Functions

Run and manage Edge Functions in your self-hosted Supabase instance.

Edge Functions work out of the box in a self-hosted Supabase setup. The functions service, API gateway routing, and a hello example function are all pre-configured.

Invoke the default function#

The default hello function is located at volumes/functions/hello/index.ts. You can invoke it immediately after starting your stack:

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curl http://<your-domain>:8000/functions/v1/hello

This returns "Hello from Edge Functions!".

Create a new function#

Step 1: Create a new directory with an index.ts file in volumes/functions/:#

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mkdir -p volumes/functions/my-function &&
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touch volumes/functions/my-function/index.ts

add the following code to index.ts:

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Deno.serve(async (req: Request) => {
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  const { name } = await req.json()
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  const message = `Hello, ${name}!`
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  return new Response(JSON.stringify({ message }), {
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    headers: { 'Content-Type': 'application/json' },
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  })
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})

Step 2: Restart the functions service to pick up the new function:#

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docker compose restart functions --no-deps

Step 3: Invoke your function:#

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curl -X POST http://<your-domain>:8000/functions/v1/my-function \
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  -H 'Content-Type: application/json' \
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  -d '{"name": "World"}'

You should be able to see the response from my-function:

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{"message":"Hello, World!"}

Custom environment variables#

Using an env file (recommended)#

For multiple variables or secrets, create a separate env file, e.g., .env.functions in your docker/ directory:

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MY_CUSTOM_VAR=some-value

Add env_file to the functions service in docker-compose.yml (variables in env_file load first, then environment values take precedence):

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functions:
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  env_file:
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    - .env.functions
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  environment:
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    JWT_SECRET: ${JWT_SECRET}
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    SUPABASE_URL: http://kong:8000

Restart the functions service:

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docker compose up -d --force-recreate --no-deps functions

Using inline environment variables#

For one or two variables, you can add them directly under environment in docker-compose.yml:

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functions:
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  environment:
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    # Custom variables
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    MY_CUSTOM_VAR: ${MY_CUSTOM_VAR}
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    # Required variables
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    JWT_SECRET: ${JWT_SECRET}
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    SUPABASE_URL: http://kong:8000

Then define MY_CUSTOM_VAR in your main .env file, or specify the value directly.

Accessing variables in functions#

All container environment variables are forwarded to function workers by main/index.ts. Access them with:

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const customVar = Deno.env.get('MY_CUSTOM_VAR')

Calling Supabase services from functions#

The functions service is pre-configured with the following environment variables:

Here's an example function that queries a table using @supabase/supabase-js:

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import { createClient } from 'https://esm.sh/@supabase/supabase-js@2'
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Deno.serve(async () => {
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  const supabase = createClient(
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    Deno.env.get('SUPABASE_URL')!,
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    Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!
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  )
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  const { data, error } = await supabase.from('todos').select('*')
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  return new Response(JSON.stringify({ data, error }), {
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    headers: { 'Content-Type': 'application/json' },
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  })
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})

Internal vs external URLs#

This is a key distinction that affects how you build URLs in your functions:

• SUPABASE_URL contains an internal Docker network hostname. Use it for server-side calls from your functions to other Supabase services (Auth, Storage, database via PostgREST). This is what the Supabase JS client should use inside functions.

• SUPABASE_PUBLIC_URL is the externally-reachable URL of your Supabase instance (e.g., <your-domain>:8000). Use it if your function needs to build URLs that HTTP clients can reach from the outside.

Managing functions via dashboard#

Self-hosted Studio mounts the same volumes/functions directory as the functions service. You can check what functions are available using Edge Functions > Functions UI.

Deploying functions to a remote server#

To deploy a function to a remote server running self-hosted Supabase, copy the function directory with scp:

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scp -r ./my-function user@<your-domain>:/path/to/self-hosted/volumes/functions/

Then restart the functions service on the remote host:

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ssh user@<your-domain> 'cd /path/to/self-hosted && docker compose restart functions --no-deps'

Copying functions from Supabase platform#

If you have existing functions on Supabase platform, you can download them and run them on your self-hosted instance. There are two ways to get the function source code:

• Dashboard - open the function details in Dashboard and click Download.
• Local development & CLI - run supabase functions download <function-name> --project-ref <ref> to download the source.

Use scp to copy the function into volumes/functions/<function-name>/ on your self-hosted instance, then restart the functions service.

For more details, see:

• Quick start - Download edge functions
• CLI commands - Download a function

Troubleshooting#

400 "missing function name in request"#

The request URL must include the function name after /functions/v1/. For example, /functions/v1/hello — not just /functions/v1/.

500 error on invocation#

Check the functions service logs:

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docker compose logs functions

Common causes: syntax errors in your function code, invalid imports, or missing dependencies.

401 "invalid JWT"#

• Check that FUNCTIONS_VERIFY_JWT matches your intent (true or false) in .env
• If verification is enabled, ensure you're passing a valid token: Authorization: Bearer <anon_key or service_role_key>

Changes to function code not reflected after editing#

Restart the functions service:

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docker compose restart functions --no-deps

Custom env vars not available in functions#

• Verify the variable is defined in docker-compose.yml (under env_file or environment)
• Recreate the functions container after changing configuration
• Check that the variable name matches exactly (case-sensitive)

Use the following command to recreate the container, not just restart:

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docker compose up -d --force-recreate --no-deps functions

Memory or timeout errors#

The default limits are 150 MB memory and 60 seconds timeout per function invocation. These are set in volumes/functions/main/index.ts. To adjust them, edit the memoryLimitMb and workerTimeoutMs values and restart the functions service.