Metacat

Metacat is a metadata service for discovering, processing, and managing data. It provides a unified REST/Thrift interface to access metadata of various data stores. Metacat supports various data sources including PostgreSQL.

Because YugabyteDB's YSQL API is wire-compatible with PostgreSQL, Metacat can connect to YugabyteDB as a data source using the PostgreSQL connector.

Setup

You can run the Docker Compose example provided in the README of the Metacat GitHub repository against YugabyteDB. To do this, you need to make the following configuration changes:

Replace the PostgreSQL Docker image with that of YugabyteDB.
Specify the entrypoint command for the YugabyteDB Docker container.
Change port from 5432 to 5433.
Change username and password to yugabyte.

Make changes in the following four files:

Create a script file named yb-init.sh with the following content and place it under metacat-functional-tests/metacat-test-cluster/datastores/postgres/docker-entrypoint-initdb.d/ in the repository. The script runs during container initialization to launch the YugabyteDB cluster.
```
bin/yugabyted start

sleep 5

bin/ysqlsh -h `hostname -i` -f /docker-entrypoint-initdb.d/world/world.sql

tail -f /dev/null
```

In the metacat-functional-tests/metacat-test-cluster/docker-compose.yml file, change the following:

Change the image to a YugabyteDB image.
Add the command and set it to the location of the script file you created.
Change the POSTGRES_USER and POSTGRES_PASSWORD.
Change the port number under environment for storage-barrier configuration.

For example:

postgresql:
    image: yugabytedb/yugabyte:2.21.0.0-b545
    command: /bin/bash /docker-entrypoint-initdb.d/yb-init.sh
    volumes:
        - ./datastores/postgres/docker-entrypoint-initdb.d:/docker-entrypoint-initdb.d:ro
    environment:
        - POSTGRES_USER=yugabyte
        - POSTGRES_PASSWORD=yugabyte
        - POSTGRES_DB=metacat
    labels:
      - "com.netflix.metacat.oss.test"
...
    storage-barrier:
        image: martin/wait:latest
        depends_on:
            - hive-metastore-db
            - postgresql
            - polaris-crdb-init
        environment:
            - TARGETS=postgresql:5433,hive-metastore-db:3306
        labels:
          - "com.netflix.metacat.oss.test"

In the metacat-functional-tests/metacat-test-cluster/etc-metacat/catalog/postgresql-96-db.properties file, change the port, username, and password as follows:

javax.jdo.option.url=jdbc:postgresql://postgresql:5433/world
javax.jdo.option.username=yugabyte
javax.jdo.option.driverClassName=org.postgresql.Driver
javax.jdo.option.password=yugabyte

In metacat-functional-tests/metacat-test-cluster/datastores/postgres/docker-entrypoint-initdb.d/world/world.sql, comment out the SET client_encoding SQL command by prefixing it with --, as it is not supported in YugabyteDB:
```
-- SET client_encoding = 'LATIN1';
```