Local Env

/scalardb:local-env — Local Environment Setup

Instructions

You are a ScalarDB local environment setup assistant. Generate Docker Compose files and setup commands for local development.

Interactive Flow

Step 1: Database Backend

Ask: "Which database backend(s) do you need?"

• MySQL
• PostgreSQL
• Cassandra
• DynamoDB Local
• Multiple (for multi-storage or 2PC testing)

Step 2: Generate Files

Generate:

1. docker-compose.yml — Database service(s)
2. Schema loading commands
3. Troubleshooting tips for common issues

Docker Compose Templates

MySQL

services:
  mysql:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: mysql
    ports:
      - "3306:3306"
    volumes:
      - mysql-data:/var/lib/mysql
    healthcheck:
      test: mysqladmin ping -h localhost -u root -pmysql
      interval: 5s
      timeout: 10s
      retries: 10

volumes:
  mysql-data:

Properties:

scalar.db.storage=jdbc
scalar.db.contact_points=jdbc:mysql://localhost:3306/
scalar.db.username=root
scalar.db.password=mysql

PostgreSQL

services:
  postgres:
    image: postgres:15
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
    ports:
      - "5432:5432"
    volumes:
      - postgres-data:/var/lib/postgresql/data
    healthcheck:
      test: pg_isready -U postgres
      interval: 5s
      timeout: 10s
      retries: 10

volumes:
  postgres-data:

Properties:

scalar.db.storage=jdbc
scalar.db.contact_points=jdbc:postgresql://localhost:5432/
scalar.db.username=postgres
scalar.db.password=postgres

Cassandra

services:
  cassandra:
    image: cassandra:3.11
    ports:
      - "9042:9042"
    environment:
      CASSANDRA_CLUSTER_NAME: test
    volumes:
      - cassandra-data:/var/lib/cassandra
    healthcheck:
      test: cqlsh -e 'describe cluster'
      interval: 10s
      timeout: 10s
      retries: 20

volumes:
  cassandra-data:

Properties:

scalar.db.storage=cassandra
scalar.db.contact_points=localhost
scalar.db.username=cassandra
scalar.db.password=cassandra

Note: Cassandra takes 30-60 seconds to start. Wait for the healthcheck to pass before loading schemas.

DynamoDB Local

services:
  dynamodb:
    image: amazon/dynamodb-local:latest
    ports:
      - "8000:8000"
    command: -jar DynamoDBLocal.jar -sharedDb

Properties:

scalar.db.storage=dynamo
scalar.db.contact_points=sample
scalar.db.username=sample
scalar.db.password=sample
scalar.db.dynamo.endpoint_override=http://localhost:8000

Multi-Storage (MySQL + Cassandra)

services:
  mysql:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: mysql
    ports:
      - "3306:3306"
    healthcheck:
      test: mysqladmin ping -h localhost -u root -pmysql
      interval: 5s
      timeout: 10s
      retries: 10

  cassandra:
    image: cassandra:3.11
    ports:
      - "9042:9042"
    environment:
      CASSANDRA_CLUSTER_NAME: test
    healthcheck:
      test: cqlsh -e 'describe cluster'
      interval: 10s
      timeout: 10s
      retries: 20

networks:
  default:
    name: sample-network

Schema Loading Commands

# Download schema loader (if not already available)
curl -OL https://github.com/scalar-labs/scalardb/releases/download/v3.16.0/scalardb-schema-loader-3.16.0.jar

# Create tables
java -jar scalardb-schema-loader-3.16.0.jar \
  --config database.properties -f schema.json --coordinator

# Delete tables (for cleanup)
java -jar scalardb-schema-loader-3.16.0.jar \
  --config database.properties -f schema.json -D --coordinator

Troubleshooting

Database not ready

• Cassandra: Wait 30-60 seconds after container starts
• MySQL: Check healthcheck with docker-compose ps
• Use docker-compose logs to check for errors

Connection refused

• Verify port mapping in docker-compose.yml
• Verify contact_points in properties file
• For MySQL: use jdbc:mysql://localhost:3306/ (with trailing slash)

Schema loading fails

• Ensure coordinator tables are created: --coordinator flag
• Verify database is running: docker-compose ps
• Check credentials match between docker-compose and properties file

Port conflict

• Change the host port mapping: "3307:3306" and update contact_points accordingly

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: wfukatsu
• Source: wfukatsu/nexus-architect
• License: MIT

Install and usage instructions live in the source repository linked above.