@platformatic/pg-hooks

Implement web hooks inside your application easily. Features:

1. delayed/scheduled invocation
2. automatic retries
3. leader/follower system (with election)
4. dead letter queue
5. cron

@platformatic/pg-hooks is also useful to create an outbox.

You can install @platformatic/pg-hooks via the Platformatic Marketplace.

Standalone Install & Setup

You can generate a standalone application with:

npx --package @platformatic/pg-hooks -c create-platformatic-pg-hooks
cd pg-hooks-app
npm i
npx plt start

You can then edit your .env file and configure the DB_URL env variable to select a PostgreSQL database.

Explore both the OpenAPI and GraphQL definitions that are now available at http://127.0.0.1:3042.

API Tutorial

To verify everything is working correctly, we will do a short tutorial

Create a target service

Run:

npx @platformatic/service create

This will create a Platformatic Service, which is essentially a Fastify template.

Now, create a platformatic-service/routes/hook.js file with the following content:

/// <reference path="../global.d.ts" />
'use strict'
/** @param {import('fastify').FastifyInstance} fastify */
module.exports = async function (fastify, opts) {
  fastify.post('/receive-my-hook', async (request, reply) => {
    request.log.info({ body: request.body }, 'Received hook')
    return 'ok'
  })
}

Then, edit platformatic-service/.env and platformatic-service/.env.sample so that PORT=3001

Run plt start to start your app. To verify that your applications is working as expected, in another shell run:

curl -X POST -H 'Content-Type: application/json' -d '{ "hello": "world" }' http://127.0.0.1:3001/receive-my-hook

This will print ok and log the received body in the console.

Create a Queue

Create a queue with

curl --request POST \
  --url http://127.0.0.1:3042/queues/ \
  --header 'Content-Type: application/json' \
  --data '{
  "name": "my test",
  "callbackUrl": "http://127.0.0.1:3001/receive-my-hook",
  "method": "POST",
  "headers": {
    "Content-Type": "application/json"
  },
  "maxRetries": 1
}'

or via OpenAPI or GraphQL web pages.

Create a Message

curl --request POST \
  --url http://0.0.0.0:3042/messages/ \
  --header 'Content-Type: application/json' \
  --data '{
  "queueId": 1,
  "body": "{ \"hello\": \"world\" }"
}'

Watch the logs in both the service and the hooks app.

Create a Cron (optional)

You can set up a cron job with:

curl --request POST \
  --url http://0.0.0.0:3042/cron/ \
  --header 'Content-Type: application/json' \
  --data '{
  "queueId": 2,
  "schedule": "* * * * *",
  "body": "{ \"hello\": \"world\" }"
}'

If you need a refresher on the CRON syntax, check out crontab.guru.

Authorization

@platformatic/pg-hooks is built around @platformatic/db, which means that authorization can be set up with its strategies.

The following will configure @platformatic/pg-hooks to only accept schedule requests by an admin that knowns the PLT_ADMIN_SECRET env variable:

{
 ...
 "authorization": {
    "adminSecret": "{PLT_ADMIN_SECRET}",
    "rules": [
      {
        "role": "anonymous",
        "entity": "queue",
        "find": false,
        "save": false,
        "delete": false
      },
      {
        "role": "anonymous",
        "entity": "cron",
        "find": false,
        "save": false,
        "delete": false
      },
      {
        "role": "anonymous",
        "entity": "message",
        "find": false,
        "save": false,
        "delete": false
      }
    ]
  },
  ...
}

For every http request, a X-PLATFORMATIC-ADMIN-SECRET header must be set with the same content of PLT_ADMIN_SECRET.

Leader election

@platformatic/pg-hooks elects a Leader using a PostgreSQL Advisory Locks, with a first-comes-win election: the first process that can grab the lock is the leader.

Currently, the leader is responsible for cron scheduling and message delivery, with all the peer responsible for creating queues and storing messages in the database.

License

Apache-2.0