Lemline requires a database to store workflow state and related data. PostgreSQL, MySQL, and H2 are supported.
Selecting a Database
Set the database type using lemline.database.type:
lemline:
database:
type: postgresql
lemline:
database:
type: mysql
lemline:
database:
type: h2
H2 is for testing only. Use PostgreSQL or MySQL in production.
PostgreSQL Configuration
Configure PostgreSQL connection settings:
lemline:
database:
type: postgresql
postgresql:
host: ${LEMLINE_PG_HOST:localhost}
port: ${LEMLINE_PG_PORT:5432}
username: ${LEMLINE_PG_USER:postgres}
password: ${LEMLINE_PG_PASSWORD:postgres}
database: ${LEMLINE_PG_DB_NAME:lemline}
PostgreSQL Parameters
lemline.database.postgresql.host
string
default:"localhost"
required
PostgreSQL server hostname or IP address
lemline.database.postgresql.port
number
default:"5432"
required
PostgreSQL server port
lemline.database.postgresql.username
string
default:"postgres"
required
Database username
lemline.database.postgresql.password
string
default:"postgres"
required
Database password. Use environment variables for security.
lemline.database.postgresql.database
string
default:"lemline"
required
Database name
Always set passwords via environment variables: ${LEMLINE_PG_PASSWORD}
PostgreSQL Example
lemline:
database:
type: postgresql
postgresql:
host: prod-db.example.com
port: 5432
username: lemline_user
password: ${LEMLINE_PG_PASSWORD}
database: lemline_production
MySQL Configuration
Configure MySQL connection settings:
lemline:
database:
type: mysql
mysql:
host: ${LEMLINE_MYSQL_HOST:localhost}
port: ${LEMLINE_MYSQL_PORT:3306}
username: ${LEMLINE_MYSQL_USER:root}
password: ${LEMLINE_MYSQL_PASSWORD:password}
database: ${LEMLINE_MYSQL_DB_NAME:lemline}
MySQL Parameters
lemline.database.mysql.host
string
default:"localhost"
required
MySQL server hostname or IP address
lemline.database.mysql.port
number
default:"3306"
required
MySQL server port
lemline.database.mysql.username
string
default:"root"
required
Database username
lemline.database.mysql.password
string
default:"password"
required
Database password. Use environment variables for security.
lemline.database.mysql.database
string
default:"lemline"
required
Database name
MySQL Example
lemline:
database:
type: mysql
mysql:
host: mysql.internal.example.com
port: 3306
username: lemline_app
password: ${LEMLINE_MYSQL_PASSWORD}
database: workflows
Database Migrations
Lemline includes Flyway migrations that are applied based on the configured database type.
Migration Configuration
lemline.database.migrate-at-start
Apply database migrations automatically on startup
lemline.database.baseline-on-migrate
Create the schema history table if it doesn’t exist
Enabling Migrations
lemline:
database:
type: postgresql
migrate-at-start: true
baseline-on-migrate: true
postgresql:
host: localhost
port: 5432
username: postgres
password: postgres
database: lemline
Migrations are versioned and applied in order. Enable baseline-on-migrate for existing databases.
Migration Behavior
Schema Detection
Flyway checks for the schema history table
Baseline Creation
If baseline-on-migrate: true, creates the history table
Version Check
Compares applied migrations with available migrations
Migration Execution
Applies pending migrations in version order
Environment-Specific Configuration
Use Quarkus profiles for different environments:
lemline:
database:
type: postgresql
postgresql:
host: localhost
port: 5432
username: postgres
password: dev-password
database: lemline_dev
'%prod':
lemline:
database:
postgresql:
host: ${LEMLINE_PROD_DB_HOST}
username: ${LEMLINE_PROD_DB_USER}
password: ${LEMLINE_PROD_DB_PASSWORD}
database: lemline_production
java -Dquarkus.profile=prod -jar lemline-runner.jar
Docker Compose Examples
For local development, start a database using Docker Compose:
docker compose -f ./examples/docker-compose.yml --profile kafka-pg up -d
docker compose -f ./examples/docker-compose.yml --profile kafka-mysql up -d
Default Credentials
PostgreSQL:
- Username:
postgres
- Password:
postgres
- Database:
lemline
MySQL:
- Username:
lemline
- Password:
lemline
- Database:
lemline
- Root password:
root
These credentials are for development only. Use strong passwords in production.
Connection Pooling
Lemline uses Quarkus Agroal for connection pooling. Advanced settings can be configured via Quarkus properties:
quarkus:
datasource:
jdbc:
min-size: 5
max-size: 20
acquisition-timeout: 10s
Troubleshooting
- Verify database is running:
docker compose ps
- Check host and port settings match your database
- Ensure network connectivity between Lemline and database
- Verify username and password are correct
- Check database grants for the user
- Ensure password environment variable is set
- Check database user has DDL permissions
- Review Flyway logs for specific errors
- For existing databases, enable
baseline-on-migrate
- Verify database name exists
- Create database manually if needed
- Check
database parameter matches actual database name
Next Steps
Messaging Configuration
Configure Kafka, RabbitMQ, or PGMQ for workflow orchestration