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      Peren documentation

      Network policy

      Which hosts a Worker may call, where credentials stay, and how to keep the peer port private.

      A Worker can call only hosts you allow. Peren sends those requests from the node process. Peer listeners are plain TCP. Keep the peer port off the public network.

      Network bindings

      Three bindings, three calls. OUTBOUND MTLS_CERTIFICATE AWS_SIGV4 env.PUBLIC_API.fetch TypeError host absent cf.mtlsCertificate missing PEM fails before listen env.AWS_BEDROCK.fetch node signs host operation failed

      No ambient fetch

      What it covers: every outbound HTTP request a Worker can cause.

      What Peren does: global fetch and outbound binding fetch run in the node process. The request host must appear in the service’s outbound host set. That set comes from type = "outbound" allowed_hosts, plus hosts from configured AI, vector, images, or container bindings. A host outside the set fails before Peren sends the request.

      There is no ambient network from the isolate. Undeclared hosts do not leave the process.

      What you configure: which hosts appear in each outbound allowlist and which upstreams those hosts reach.

      What you can check: fetch to a host outside the allowlist fails, and Peren does not send that request. See Outbound fetch and Outbound network.

      Client mTLS and SigV4 outside the isolate

      What it covers: client certificates and AWS signing keys used on outbound requests.

      What Peren does: type = "mtls_certificate" loads PEM from process environment variables into the host. The Worker receives an opaque handle with no fetch method and cannot read the PEM. Pass the handle as fetch(url, { cf: { mtlsCertificate: env.NAME } }) on a fetch to an allowed host.

      type = "aws_sigv4" signs in the node process. The Worker calls env.NAME.fetch. It does not receive access keys or secrets. Signing overwrites authorization, x-amz-date, x-amz-content-sha256, x-amz-security-token, and host in the host.

      What you configure: which PEM and key environment variables exist before listeners open, which hosts those bindings may call, and rotation of that material.

      What you can check: an mTLS binding on env is an object with no PEM. A SigV4 binding does not expose access keys. See Client mTLS and AWS SigV4.

      Redirect targets are not re-checked

      What it covers: the host reached after an outbound HTTP redirect.

      What Peren does: allowlist membership for the initial request URL host. Redirect targets of outbound fetch are not checked again against allowed_hosts.

      What you configure: that allowlisted hosts do not redirect to destinations the fleet must not reach, or that upstreams refuse such redirects.

      What you can check: Peren checks the URL the Worker passed. A redirect can then reach a host that is not in allowed_hosts.

      Peer listen and [mtls]

      What it covers: the peer listener and control plane on [node].listen.

      What Peren does: [mtls] certificate paths are required in the fleet file. Public sockets and the peer listener accept plain TCP. The process does not terminate inbound TLS with the [mtls] material.

      Outbound Worker client certificates are a separate mtls_certificate binding. They are not peer inbound TLS.

      What you configure: keeping the peer port off the public network with host firewall rules, security groups, or cluster network policy. Terminate public TLS at a reverse proxy or load balancer in front of public sockets.

      What you can check: peer and public listeners accept plain TCP. Certificate paths in [mtls] do not make those listeners speak TLS. See Networking and ports.