Configuration

Spring Profiles

Secure Link API uses Spring profiles to manage different environments:

Profile	Purpose	Database
`dev`	Local development	MySQL
`prod`	Production deployment	MySQL
`test`	Automated testing	H2 (in-memory)

Activating a Profile

SPRING_PROFILES_ACTIVE=dev mvn spring-boot:run

Environment Variables

The application uses environment variables for sensitive configuration. These can be set in a .env file (loaded automatically) or as system environment variables.

Required Variables

Variable	Description	Example
`BASE_URL`	Public URL for the API	`http://localhost:8080`
`DB_HOST`	MySQL host address	`localhost`
`DB_PORT`	MySQL port	`3307`
`DB_NAME`	Database name	`secure_link`
`DB_USERNAME`	Database user	`admin`
`DB_PASSWORD`	Database password	`secure_password`

For production deployments, use DB_URL instead of individual host/port/name variables for better security and flexibility.

Example .env File

.env

BASE_URL=http://localhost:8080
DB_HOST=localhost
DB_PORT=3307
DB_NAME=secure_link
DB_USERNAME=your_username
DB_PASSWORD=your_password

Application Properties

Core Configuration

The base configuration in application.properties:

application.properties

# Application
spring.application.name=secure-link
server.port=8080

# Environment file import
spring.config.import=optional:file:.env[.properties]

# Base URL for link generation
app.base-url=${BASE_URL:http://localhost:8080}

# File storage location
app.storage.path=/tmp/uploads/

# Default link time-to-live (ISO-8601 Duration)
app.link.default-ttl=PT24H

# File upload limits
spring.servlet.multipart.max-file-size=50MB
spring.servlet.multipart.max-request-size=50MB

# CORS configuration
app.cors.allowed-origins=http://localhost:4200,http://127.0.0.1:4200

# Logging pattern (includes correlation ID)
logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss.SSS} %-5level [%thread] [%X{correlationId}] %logger{36} - %msg%n

Dev Profile Configuration

Configuration specific to application-dev.properties:

application-dev.properties

# Database
spring.datasource.url=jdbc:mysql://${DB_HOST:localhost}:${DB_PORT:3307}/${DB_NAME:secure_link}
spring.datasource.username=${DB_USERNAME}
spring.datasource.password=${DB_PASSWORD}
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# JPA
spring.jpa.hibernate.ddl-auto=validate
spring.jpa.show-sql=false

# Flyway migrations
spring.flyway.enabled=true
spring.flyway.locations=classpath:db/migration
spring.flyway.baseline-on-migrate=true

# Actuator endpoints
management.endpoints.web.exposure.include=health,prometheus
management.endpoint.health.show-details=always
management.health.defaults.enabled=true

# Logging
logging.level.root=INFO
logging.level.br.com.walyson.secure_link=INFO

Production Profile Configuration

Configuration for application-prod.properties:

application-prod.properties

# Database (use full URL for production)
spring.datasource.url=${DB_URL}
spring.datasource.username=${DB_USERNAME}
spring.datasource.password=${DB_PASSWORD}
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

# JPA
spring.jpa.hibernate.ddl-auto=validate
spring.jpa.show-sql=false

# Flyway
spring.flyway.enabled=true

# Actuator (restricted in production)
management.endpoints.web.exposure.include=health
management.endpoint.health.show-details=never
management.health.defaults.enabled=true

# Logging
logging.level.root=INFO
logging.level.br.com.walyson.secure_link=INFO

Production profile hides health check details for security. Only the overall status is exposed.

Test Profile Configuration

Configuration for application-test.properties:

application-test.properties

# H2 in-memory database
spring.datasource.url=jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1
spring.datasource.driver-class-name=org.h2.Driver
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.hibernate.ddl-auto=create-drop

# Disable Flyway for tests
spring.flyway.enabled=false

Configuration Properties Reference

Link Settings

Property	Description	Default
`app.link.default-ttl`	Default link expiration time (ISO-8601)	`PT24H` (24 hours)
`app.base-url`	Base URL for link generation	`http://localhost:8080`

Storage Settings

Property	Description	Default
`app.storage.path`	Directory for uploaded files	`/tmp/uploads/`
`spring.servlet.multipart.max-file-size`	Maximum file size	`50MB`
`spring.servlet.multipart.max-request-size`	Maximum request size	`50MB`

CORS Settings

Property	Description	Default
`app.cors.allowed-origins`	Comma-separated allowed origins	`http://localhost:4200,http://127.0.0.1:4200`

Database Settings

Property	Description
`spring.datasource.url`	JDBC connection URL
`spring.datasource.username`	Database username
`spring.datasource.password`	Database password
`spring.jpa.hibernate.ddl-auto`	Schema generation strategy (`validate` recommended)

Actuator Settings

Property	Description
`management.endpoints.web.exposure.include`	Exposed actuator endpoints
`management.endpoint.health.show-details`	Health endpoint detail level

Monitoring and Observability

Health Checks

The application provides detailed health information at /actuator/health:

Database connectivity - Verifies MySQL connection
Disk space - Checks available storage
Storage health - Validates upload directory
Expiration job - Monitors scheduled task status

Prometheus Metrics

Exposed at /actuator/prometheus (dev profile only):

curl http://localhost:8080/actuator/prometheus

Includes custom business metrics:

secure_link_resolve_success_total - Successful link resolutions
secure_link_resolve_failure_total - Failed access attempts
Standard JVM, HTTP, and database metrics

Logging Configuration

Correlation IDs

Every request includes a correlation ID in logs and response headers:

2026-03-04 10:15:30.123 INFO [http-nio-8080-exec-1] [abc-123-def-456] c.w.s.controller.LinkController - Processing request

The correlation ID is also returned in the X-Correlation-Id response header.

Log Levels

Adjust log levels per package:

logging.level.root=INFO
logging.level.br.com.walyson.secure_link=DEBUG
logging.level.org.springframework.web=DEBUG
logging.level.org.hibernate.SQL=DEBUG

Security Configuration

Password Encryption

Link passwords are encrypted using BCrypt with strength 10:

BCryptPasswordEncoder(10)

CORS Policy

Configure allowed origins for cross-origin requests:

app.cors.allowed-origins=https://example.com,https://app.example.com

Database Migration

Flyway automatically manages database schema versions:

Migration scripts: src/main/resources/db/migration/
Naming convention: V{version}__{description}.sql
Baseline on migrate: Enabled for existing databases

Common Flyway Commands

# View migration status
mvn flyway:info

# Repair checksums
mvn flyway:repair

# Migrate to latest
mvn flyway:migrate

Production Recommendations

Security Best Practices:

Use strong database passwords
Set management.endpoint.health.show-details=never
Limit CORS origins to trusted domains
Use HTTPS for BASE_URL in production
Store .env file securely, never commit to version control

Performance Tuning

# Database connection pool
spring.datasource.hikari.maximum-pool-size=10
spring.datasource.hikari.minimum-idle=5

# JPA batch processing
spring.jpa.properties.hibernate.jdbc.batch_size=20

File Storage

For production, consider using:

Network-attached storage (NAS)
Object storage (S3, MinIO)
Persistent volumes in containerized environments

Update app.storage.path accordingly:

app.storage.path=/var/secure-link/uploads/

Next Steps

Deploy with Docker for containerized environments
Install locally for development
Review API Reference for usage

Deployment

Monitoring

Spring Profiles

Activating a Profile

Environment Variables

Required Variables

Example .env File

Application Properties

Core Configuration

Dev Profile Configuration

Production Profile Configuration

Test Profile Configuration

Configuration Properties Reference

Link Settings

Storage Settings

CORS Settings

Database Settings

Actuator Settings

Monitoring and Observability

Health Checks

Prometheus Metrics

Logging Configuration

Correlation IDs

Log Levels

Security Configuration

Password Encryption

CORS Policy

Database Migration

Common Flyway Commands

Production Recommendations

Performance Tuning

File Storage

Next Steps

Build docs developers (and LLMs) love

Deployment

Monitoring

Documentation Index

​Spring Profiles

​Activating a Profile

​Environment Variables

​Required Variables

​Example .env File

​Application Properties

​Core Configuration

​Dev Profile Configuration

​Production Profile Configuration

​Test Profile Configuration

​Configuration Properties Reference

​Link Settings

​Storage Settings

​CORS Settings

​Database Settings

​Actuator Settings

​Monitoring and Observability

​Health Checks

​Prometheus Metrics

​Logging Configuration

​Correlation IDs

​Log Levels

​Security Configuration

​Password Encryption

​CORS Policy

​Database Migration

​Common Flyway Commands

​Production Recommendations

​Performance Tuning

​File Storage

​Next Steps

Build docs developers (and LLMs) love

Spring Profiles

Activating a Profile

Environment Variables

Required Variables

Example .env File

Application Properties

Core Configuration

Dev Profile Configuration

Production Profile Configuration

Test Profile Configuration

Configuration Properties Reference

Link Settings

Storage Settings

CORS Settings

Database Settings

Actuator Settings

Monitoring and Observability

Health Checks

Prometheus Metrics

Logging Configuration

Correlation IDs

Log Levels

Security Configuration

Password Encryption

CORS Policy

Database Migration

Common Flyway Commands

Production Recommendations

Performance Tuning

File Storage

Next Steps