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strfry Policies ​

Nostrify policies can be used with the strfry relay to create custom policy scripts.

For more information about strfry policy plugins, see strfry: Write policy plugins.

System Setup ​

To get up and running, you will need to install Deno on the same machine as strfry:

sh
sudo apt install -y unzip
curl -fsSL https://deno.land/install.sh | sudo DENO_INSTALL=/usr/local sh

Create an entrypoint file somewhere and make it executable:

sh
sudo touch /opt/policy.ts
sudo chmod +x /opt/policy.ts

Let's start with a minimal policy file that accepts all events:

ts
#!/bin/sh
//bin/true; exec deno run -A "$0" "$@"

import { NoOpPolicy } from 'jsr:@nostrify/policies';
import { strfry } from 'jsr:@nostrify/strfry;

const policy = new NoOpPolicy(); // accept all events

await strfry(policy);

Finally, edit strfry.conf and enable the policy:

diff
     writePolicy {
         # If non-empty, path to an executable script that implements the writePolicy plugin logic
-        plugin = ""
+        plugin = "/opt/policy.ts"
 
         # Number of seconds to search backwards for lookback events when starting the writePolicy plugin (0 for no lookback)
         lookbackSeconds = 0

That's it! 🎉 Now you should check strfry logs (journalctl -eu strfry) to ensure everything is working okay.

Policy Script ​

Now you can write your custom policy. Here's a starting point:

ts
#!/bin/sh
//bin/true; exec deno run --unstable-kv -A "$0" "$@"
import {
  AntiDuplicationPolicy,
  FiltersPolicy,
  HellthreadPolicy,
  KeywordPolicy,
  PipePolicy,
  PowPolicy,
  RegexPolicy,
} from 'jsr:@nostrify/policies';
import { strfry } from 'jsr:@nostrify/strfry';

// Create a regular policy object however you want.
const policy = new PipePolicy([
  new FiltersPolicy([{ kinds: [0, 1, 3, 5, 7, 1984, 9734, 9735, 10002] }]),
  new KeywordPolicy(['https://t.me/']),
  new RegexPolicy(/(🟠|🔥|😳)ChtaGPT/i),
  new PubkeyBanPolicy(['e810fafa1e89cdf80cced8e013938e87e21b699b24c8570537be92aec4b12c18']),
  new HellthreadPolicy({ limit: 100 }),
  new AntiDuplicationPolicy({ kv: await Deno.openKv(), expireIn: 60000, minLength: 50 }),
]);

// Call the `strfry` function at the bottom of the file.
// This hooks up to stdin/stdout and runs the policy on strfry input.
await strfry(policy);

NOTE

The comments at the top of the file are necessary for strfry to execute the script in Deno correctly. To use advanced features of Deno, it may need to be modified. In this case, the --unstable-kv flag was added.

TIP

See the Policy List for a full list of available policies in Nostrify.

How it Works ​

The strfry() function in Nostrify acts as a glue layer between strfry's stdin/stdout and Nostrify policies.

This means you can use Nostrify to write policies for Ditto and strfry at the same time.

See @nostrify/strfry on JSR for more details.

Advanced Policies ​

Relay Introspection ​

It's possible to make the policy script connect back to the strfry relay itself. For example, this policy fetches the kind 0 of each event's author from the relay, and accepts only events from users with verified NIP-05 domains:

ts
#!/bin/sh
//bin/true; exec deno run -A '$0' '$@'

import { NRelay1 } from 'jsr:@nostrify/nostrify';
import { DomainPolicy } from 'jsr:@nostrify/policies';
import { strfry } from 'jsr:@nostrify/strfry';

const store = new NRelay1('ws://127.0.0.1:7777'); // connect to strfry relay
const policy = new DomainPolicy(store); // enforce valid NIP-05 authors

await strfry(policy);

Policy Timeouts ​

If your policy connects to external services (like doing NIP-05 lookups), it's imperative to pass a timeout, otherwise the request will be allowed to run forever which would harm performance of your relay.

Do so by passing a second argument to the strfry function:

ts
await strfry(policy, () => ({ signal: AbortSignal.timeout(3000) })); // 3s
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