postnat

Publish messages to NATS via Postgres' LISTEN/NOTIFY feature.

Why would I use this?

Let's assume you already have a postgresql backed application and you want to introduce a Messaging layer but don't have the resources to modify the system to introduce more dependencies or you just want to put it off for a bit more.

postnat helps you use the facilities of Postgres to publish messages to a NATS server with minimal changes to your code.

NOTIFY 'time_us_east', '<binary-or-json-message-here>';

What postnat does is basically listen to all registered patterns and publishes the payloads to the configured NATS server.

Usage

You can run it like so:

$ postnat --config "postnat.toml" run

CLI

Usage: postnat <command>

Publish messages to NATS from PostgreSQL LISTEN/NOTIFY messages

Flags:
  -h, --help                     Show context-sensitive help.
      --config="postnat.toml"    Location of configuration file
      --debug                    Enable debug mode
      --version                  Show version and quit

Commands:
  run    Start the postnat daemon

Run "postnat <command> --help" for more information on a command.

Configuration

[postgres]
host = "localhost"
port = 5432
database = "database"
username = "username"
password = "password"
sslmode = "disable"

[nats]
url = "nats://username:password@localhost:4222"
max_reconnects = 10

[topics]
listen_for = ["users", "users_id"]
# optional topic prefix
prefix = "app."
# This replaces the underscore when publishing to nats, e.g. emails_signup -> emails.signup
replace_underscore_with_dot = true

Building

First clone this repo:

$ git clone https://github.com/zikani03/postnat
$ cd postnat

Building from source

$ go build ./cmd/postnat.go

Docker, with docker compose

Create a configuration file named development.toml and update as appropriate, then run:

$ docker compose up

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MIT LICENSE © Zikani Nyirenda Mwase