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Setting up OracleDB in a Spring Boot application doesn’t have to be complicated. By using Docker for development and Kubernetes for production, you can ensure your setup is consistent and secure. And with Spring Boot's support for profile-based configurations via application.properties, you can easily separate dev and prod settings to keep things clean and manageable.
In this guide, we’ll walk through configuring OracleDB using Docker locally and setting up environment-specific files (application-dev.properties and application-prod.properties). We’ll also explore how to pull production configuration from Kubernetes ConfigMaps and Secrets.

1. Add the Required Dependencies

First, make sure your pom.xml includes the Oracle JDBC driver (note: Oracle requires you to manually install it due to licensing restrictions) and optionally dependencies for Kubernetes config handling. 
<dependencies>
  <!-- Oracle JDBC driver (manually install to your local Maven repository) -->
  <dependency>
    <groupId>com.oracle.database.jdbc</groupId>
    <artifactId>ojdbc8</artifactId>
    <version>19.8.0.0</version>
  </dependency>

  <!-- Spring Boot JPA support -->
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
  </dependency>

  <!-- (Optional) Spring Cloud Kubernetes for auto-config support -->
  <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-kubernetes-fabric8</artifactId>
  </dependency>
</dependencies>

2. Run OracleDB with Docker for Local Development

Use the gvenzl/oracle-free image to run OracleDB locally with Docker: 
docker run -d --name oracledb \
  -p 1521:1521 \
  -e ORACLE_PASSWORD=devpass \
  -e APP_USER=devuser \
  -e APP_USER_PASSWORD=devpass \
  gvenzl/oracle-free:latest
This will launch OracleDB with user devuser and password devpass, listening on the default port 1521.

3. Configure application-dev.properties

Now create a src/main/resources/application-dev.properties file for your development settings: 
spring.datasource.url=jdbc:oracle:thin:@localhost:1521/ORCLCDB
spring.datasource.username=devuser
spring.datasource.password=devpass
spring.datasource.driver-class-name=oracle.jdbc.OracleDriver

spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.Oracle12cDialect
To activate this configuration locally, run your app with: 
SPRING_PROFILES_ACTIVE=dev
Or pass it via Maven: 
./mvnw spring-boot:run -Dspring-boot.run.profiles=dev

4. Prepare OracleDB for Kubernetes Production

In production, it’s best practice not to hardcode any configuration. Instead, store values in Kubernetes ConfigMaps and Secrets.

4.1: Create a ConfigMap for General Oracle Settings

apiVersion: v1
kind: ConfigMap
metadata:
  name: oracle-config
data:
  spring.datasource.url: jdbc:oracle:thin:@oracle-service:1521/ORCLCDB
  spring.datasource.driver-class-name: oracle.jdbc.OracleDriver
  spring.jpa.hibernate.ddl-auto: validate
  spring.jpa.properties.hibernate.dialect: org.hibernate.dialect.Oracle12cDialect

4.2: Create a Secret for Credentials

apiVersion: v1
kind: Secret
metadata:
  name: oracle-secret
type: Opaque
data:
  spring.datasource.username: cHJvZHVzZXI=  # base64 for 'produser'
  spring.datasource.password: cHJvZHBhc3M=  # base64 for 'prodpass'

5. Configure application-prod.properties

This configuration will read values from the environment, which will be provided by Kubernetes: 
spring.datasource.url=${SPRING_DATASOURCE_URL}
spring.datasource.username=${SPRING_DATASOURCE_USERNAME}
spring.datasource.password=${SPRING_DATASOURCE_PASSWORD}
spring.datasource.driver-class-name=${SPRING_DATASOURCE_DRIVER_CLASS_NAME}

spring.jpa.hibernate.ddl-auto=${SPRING_JPA_HIBERNATE_DDL_AUTO}
spring.jpa.properties.hibernate.dialect=${SPRING_JPA_PROPERTIES_HIBERNATE_DIALECT}
Then, in your Kubernetes Deployment YAML, mount the environment variables from the ConfigMap and Secret: 
env:
  - name: SPRING_PROFILES_ACTIVE
    value: prod
  - name: SPRING_DATASOURCE_URL
    valueFrom:
      configMapKeyRef:
        name: oracle-config
        key: spring.datasource.url
  - name: SPRING_DATASOURCE_DRIVER_CLASS_NAME
    valueFrom:
      configMapKeyRef:
        name: oracle-config
        key: spring.datasource.driver-class-name
  - name: SPRING_JPA_HIBERNATE_DDL_AUTO
    valueFrom:
      configMapKeyRef:
        name: oracle-config
        key: spring.jpa.hibernate.ddl-auto
  - name: SPRING_JPA_PROPERTIES_HIBERNATE_DIALECT
    valueFrom:
      configMapKeyRef:
        name: oracle-config
        key: spring.jpa.properties.hibernate.dialect
  - name: SPRING_DATASOURCE_USERNAME
    valueFrom:
      secretKeyRef:
        name: oracle-secret
        key: spring.datasource.username
  - name: SPRING_DATASOURCE_PASSWORD
    valueFrom:
      secretKeyRef:
        name: oracle-secret
        key: spring.datasource.password

6. Verifying Your Oracle Connection

To verify that your app is properly connected to OracleDB, try injecting a repository and querying a simple entity: 
@RestController
public class HealthCheckController {
    @Autowired
    private YourEntityRepository repo;

    @GetMapping("/ping")
    public ResponseEntity<String> ping() {
        return ResponseEntity.ok("Connected: " + repo.count());
    }
}
If everything is wired correctly, you should get a valid response from /ping.

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