single-cluster#

Overview#

This project simplifies ScyllaDB cluster configuration with 3 nodes for local testing using Docker and Docker Compose. It facilitates easy deployment and testing of ScyllaDB, a highly scalable NoSQL database.

Prerequisites#

Before you begin, make sure the following software is installed on your system:

Getting Started#

Clone this repository#

git clone https://github.com/gvieira18/ws-scylla.git

Configure ScyllaDB settings#

Before starting the cluster, ensure the aio-max-nr value is sufficient (e.g., 1048576 or more). Check and adjust the value with the following commands:

cat /proc/sys/fs/aio-max-nr

Attention

The next command adds a file inside the /etc/sysctl.d folder for startup loading.

echo fs.aio-max-nr=1048576 | sudo tee /etc/sysctl.d/41-aio_max_nr.conf && sudo sysctl --system

Optional

Modify the docker-compose.yml file to customize ScyllaDB settings, such as port mappings, volume mounts, and network configurations.

Start the ScyllaDB container#

Use the following command to pull the ScyllaDB Docker image (if not already downloaded) and start the container in the background:

docker compose up --detach # or docker compose up -d

Maintenance#

Accessing the Database#

  • CQLSH (Cassandra Query Language Shell)

docker compose exec -it ws-scylla-1 cqlsh
# or
docker compose exec -it ws-scylla-2 cqlsh
# or
docker compose exec -it ws-scylla-3 cqlsh

CQLSH is the command-line interface for interacting with ScyllaDB using the Cassandra Query Language (CQL). It allows you to execute CQL queries and manage the database.

  • Nodetool

docker compose exec -it ws-scylla-1 nodetool status
# or
docker compose exec -it ws-scylla-2 nodetool status
# or
docker compose exec -it ws-scylla-3 nodetool status

Nodetool is a command-line utility for managing and monitoring ScyllaDB clusters. It provides various operations, such as checking the status of nodes, compaction, repair, and more.

  • Inside the Docker Network

The docker-compose.yml file defines a specific network (ws-scylla) for internal usage. Integration with other projects within different Docker Compose specifications is possible.

services:
  custom-service:
    networks:
      - ws-scylla
networks:
  ws-scylla:
    external: true

After starting the custom service, it registers within the ws-scylla network. The ScyllaDB configuration already defines default ports for access.

Service Name

Host

Port

ws-scylla-1

ws-scylla-1

9042

ws-scylla-2

ws-scylla-2

9042

ws-scylla-3

ws-scylla-3

9042

 
const client = new cassandra.Client({
  contactPoints: ['ws-scylla-1:9042', 'ws-scylla-2:9042', 'ws-scylla-3:9042'],
  localDataCenter: 'datacenter1',
  keyspace: 'system'
});

  • Outside the Docker Network

The default docker-compose.yml file enables the following ports for external access to the DBMS/SGDB or directly to the database driver:

Service Name

Host

Port

ws-scylla-1

localhost

9040

ws-scylla-2

localhost

9041

ws-scylla-3

localhost

9042

Using the same example from internal access:

const client = new cassandra.Client({
  contactPoints: ['localhost:9040', 'localhost:9041', 'localhost:9042'],
  localDataCenter: 'datacenter1',
  keyspace: 'system'
});

Access via Datagrip, which belongs to IntelliJ, follows the JDBC standard. You can build the JDBC URL as follows:

URL="jdbc:cassandra://localhost:9040,localhost:9041,localhost:9042/system"

Stop and Remove Cluster/Container#

  • Stop the Cluster

docker compose stop

  • Stop and Remove Containers

docker compose down

Danger

Removing the volume also means removing any information stored in the database
So proceed with caution and make a backup if necessary.
docker compose down --volumes # or docker compose down -v

References#