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Cardano Address Monitor

Monitor one or more Cardano addresses for transactions and receive events with the transactions information. Designed to avoid processing a transaction twice.

How does it work?

When a transaction received by specified addresses is considered immutable the monitor sends an event into a PosgtreSQL channel. You can subscribe to the PostgreSQL channel to receive the events. The events contain information about the transactions received.

A transaction is immutable when there are k blocks added on top of the block containing the transaction. k is the Cardano security parameter. Since different applications can consider a different probability of being immutable, you can configure k for the monitor, i.e. you can configure how many blocks must be added on top of the block containing a transaction before the monitor sends the event. By default it is 2160.

Installation

The address monitor is installed just by deploying a PostgreSQL schema in the same database that cardano-db-sync uses.

Installing into an already running cardano-db-sync instance

psql -U<user> -d<database> -h<host> -f ./monitor-schema/schema.sql -v address='<address>' -v k=2160

The database name must be the database used by cardano-db-sync. It is usually called cexplorer.

Install a full stack with docker-compose

Executing the restart script deletes the PostgreSQL volume

You may need to change the ownership of test/pgpass-mainnet and test/ledger-state/mainnet to belong to user 1001.

./test/restart.sh

The bove command will use test/docker-compose.yaml to deploy a Shareslake node, shareslake-db-sync, postgresql and install the monitor. You can edit the docker-compose images and substitute the configuration and genesis files under test to deploy a Cardano mainnet node instead.

NOTE: shareslake-db-sync is the same as cardano-db-sync but used to connect to the Shareslake network instead of Cardano mainnet.

Check installation

Subscribe with the example NodeJS listener to watch events. You can take the file as a base to build your custom scripts:

cd listener && node index.js

It will just listen events and log them.

Listening events

You can listen events just by subscribing to the address_monitor channel in PostgreSQL.

Avoid duplicated events

As far as you don't delete data from PostgreSQL, an even't should never be send twice.

TODO

[ ] Support for tracking multiple addresses.