Chainhook Client

A TypeScript client library that allows you to configure and listen for fully-typed Chainhook predicate events.

You can either create predicates and send them to a Chainhook node manually or use the included web server helpers to handle all node interactions transparently.

Quick Start

1. Install npm package

   npm install @hirosystems/chainhook-client

2. Create a Predicate object for every Chainhook event you're interested in. See the Chainhook README for more examples.

   import { ServerPredicate } from "@hirosystems/chainhook-client";
   import { randomUUID } from "crypto";
   
   const uuid = randomUUID();
   const predicate: ServerPredicate = {
       uuid,
       name: "test",
       version: 1,
       chain: "stacks",
       networks: {
           mainnet: {
               // `then_that` will be filled in automatically.
               if_this: {
                   scope: 'block_height',
                   higher_than: 100000,
               }
           }
       }
   };

3. Create configuration objects for the local server and the Chainhook node you'll be interacting with

   import { ServerOptions, ChainhookNodeOptions } from "@hirosystems/chainhook-client";
   
   // Local server options
   const opts: ServerOptions = {
       hostname: "0.0.0.0",
       port: 3000,
       auth_token: "<random_string>",
       // Configure this value to a hostname the Chainhook node can use to reach our local server.
       // e.g. http://local.server:3000
       external_base_url: "<external_base_url>"
   };
   
   // Chainhook node options
   const chainhook: ChainhookNodeOptions = {
       base_url: "<node_base_url>"
   };

4. Declare and start the event server

   import { Payload } from "@hirosystems/chainhook-client";
   
   const server = new ChainhookEventObserver(opts, chainhook);
   server.start(
       [predicate],
       async (uuid: string, payload: Payload) => {
           // This handler will be called for every chainhook event received by our server
           console.log(uuid);
           console.log(payload);
       }
   )
       .catch(e => console.error(e));
   const close = async () => {
       await server.close();
   }
   process.once('SIGINT', close);
   process.once('unhandledRejection', close);
   process.once('uncaughtException', close);
   process.once('beforeExit', close);

   Make sure you close the server gracefully in the event of an error so we can de-register our predicates correctly from the remote Chainhook node.

Type Definitions

This library includes type definitions for all possible Chainhook predicate configurations and event payloads in the form of Typebox schemas. If you need to compile or validate any of the supplied types, generate JSON schemas, etc., you can use all of Typebox's tools to do so.