Peren documentation
Outbound fetch
Allowlist hosts and call them through an outbound binding.
An outbound binding lets a Worker call specific hosts through env.NAME.fetch. Peren refuses any other host for that binding. The binding carries no credentials.
Prerequisites
- A fleet file with
[node],[bucket],[mtls], one service, and one socket - A Worker bundle that exports
fetch - The upstream host name you will allowlist
Configure the binding
Write fleet.toml:
[node]
node_id = "00000000-0000-0000-0000-000000000001"
advertise_addr = "127.0.0.1:7000"
listen = "127.0.0.1:7000"
[bucket]
kind = "memory"
[mtls]
ca_cert_path = "./certs/ca.pem"
leaf_cert_path = "./certs/leaf-cert.pem"
leaf_key_path = "./certs/leaf-key.pem"
[[services]]
name = "api"
worker_bundle_path = "worker.js"
compatibility_date = "2026-01-01"
[services.bindings.PUBLIC_API]
type = "outbound"
allowed_hosts = ["api.example.com"]
[[sockets]]
name = "public"
listen = "127.0.0.1:8080"
service = "api"type must be outbound. allowed_hosts lists host names the binding may call.
Call the binding
Write worker.js:
export default {
async fetch(request, env) {
return env.PUBLIC_API.fetch("https://api.example.com/status");
},
};The Worker calls env.PUBLIC_API.fetch. Global fetch uses the union of outbound allowlists on that service. Local, private and metadata-style destinations are refused even when allowlisted. Redirect responses are returned to the Worker; Peren does not follow them in the host client.
Success
The upstream HTTP status and body are returned to the Worker as the Response from env.PUBLIC_API.fetch.
Failure
A host that is not in allowed_hosts throws TypeError before the request leaves the node.