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Create the Spring Boot project

Table of contents

Set up the project

Create a Spring Boot project from Spring Initializr by selecting the Spring Web, Validation, JDBC API, PostgreSQL Driver, Spring Security, OAuth2 Resource Server, and Testcontainers starters.

Alternatively, clone the guide repository.

After generating the application, add the testcontainers-keycloak community module and REST Assured as test dependencies.

The key dependencies in pom.xml are:

<properties>
    <java.version>17</java.version>
    <testcontainers.version>2.0.4</testcontainers.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-validation</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-oauth2-resource-server</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-testcontainers</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.testcontainers</groupId>
        <artifactId>testcontainers-junit-jupiter</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.testcontainers</groupId>
        <artifactId>testcontainers-postgresql</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.github.dasniko</groupId>
        <artifactId>testcontainers-keycloak</artifactId>
        <version>3.4.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>io.rest-assured</groupId>
        <artifactId>rest-assured</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

Create the domain model

Create a Product record that represents the domain object:

package com.testcontainers.products.domain;

import jakarta.validation.constraints.NotEmpty;

public record Product(Long id, @NotEmpty String title, String description) {}

Create the repository

Implement ProductRepository using Spring JdbcClient to interact with a PostgreSQL database:

package com.testcontainers.products.domain;

import java.util.List;
import org.springframework.jdbc.core.simple.JdbcClient;
import org.springframework.jdbc.support.GeneratedKeyHolder;
import org.springframework.jdbc.support.KeyHolder;
import org.springframework.stereotype.Repository;

@Repository
public class ProductRepository {

  private final JdbcClient jdbcClient;

  public ProductRepository(JdbcClient jdbcClient) {
    this.jdbcClient = jdbcClient;
  }

  public List<Product> getAll() {
    return jdbcClient.sql("SELECT * FROM products").query(Product.class).list();
  }

  public Product create(Product product) {
    String sql =
      "INSERT INTO products(title, description) VALUES (:title,:description) RETURNING id";
    KeyHolder keyHolder = new GeneratedKeyHolder();
    jdbcClient
      .sql(sql)
      .param("title", product.title())
      .param("description", product.description())
      .update(keyHolder);
    Long id = keyHolder.getKeyAs(Long.class);
    return new Product(id, product.title(), product.description());
  }
}

Add a schema creation script

Create src/main/resources/schema.sql to initialize the products table:

CREATE TABLE products (
    id bigserial primary key,
    title varchar not null,
    description text
);

Enable schema initialization in src/main/resources/application.properties:

spring.sql.init.mode=always

For production applications, use a database migration tool like Flyway or Liquibase instead.

Implement the API endpoints

Create ProductController with endpoints to fetch all products and create a product:

package com.testcontainers.products.api;

import com.testcontainers.products.domain.Product;
import com.testcontainers.products.domain.ProductRepository;
import jakarta.validation.Valid;
import java.util.List;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/products")
class ProductController {

  private final ProductRepository productRepository;

  ProductController(ProductRepository productRepository) {
    this.productRepository = productRepository;
  }

  @GetMapping
  List<Product> getAll() {
    return productRepository.getAll();
  }

  @PostMapping
  @ResponseStatus(HttpStatus.CREATED)
  Product createProduct(@RequestBody @Valid Product product) {
    return productRepository.create(product);
  }
}

Configure OAuth 2.0 security

Create a SecurityConfig class that protects the API endpoints using JWT token-based authentication:

package com.testcontainers.products.config;

import static org.springframework.security.config.Customizer.withDefaults;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpMethod;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configurers.CorsConfigurer;
import org.springframework.security.config.annotation.web.configurers.CsrfConfigurer;
import org.springframework.security.config.http.SessionCreationPolicy;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
@EnableWebSecurity
class SecurityConfig {

  @Bean
  SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
    http
      .authorizeHttpRequests(c ->
        c
          .requestMatchers(HttpMethod.GET, "/api/products")
          .permitAll()
          .requestMatchers(HttpMethod.POST, "/api/products")
          .authenticated()
          .anyRequest()
          .authenticated()
      )
      .sessionManagement(c ->
        c.sessionCreationPolicy(SessionCreationPolicy.STATELESS)
      )
      .cors(CorsConfigurer::disable)
      .csrf(CsrfConfigurer::disable)
      .oauth2ResourceServer(oauth2 -> oauth2.jwt(withDefaults()));
    return http.build();
  }
}

This configuration:

  • Permits unauthenticated access to GET /api/products.
  • Requires authentication for POST /api/products and all other endpoints.
  • Configures the OAuth 2.0 Resource Server with JWT token-based authentication.
  • Disables CORS and CSRF because this is a stateless API.

Add the JWT issuer URI to application.properties:

spring.security.oauth2.resourceserver.jwt.issuer-uri=http://localhost:9090/realms/keycloaktcdemo

Export the Keycloak realm configuration

Before writing the tests, export a Keycloak realm configuration so that the test environment can import it automatically. Start a temporary Keycloak instance:

$ docker run -p 9090:8080 \
    -e KEYCLOAK_ADMIN=admin \
    -e KEYCLOAK_ADMIN_PASSWORD=admin \
    quay.io/keycloak/keycloak:25 start-dev

Open http://localhost:9090 and sign in to the Admin Console with admin/admin. Then set up the realm:

  1. In the top-left corner, select the realm drop-down and create a realm named keycloaktcdemo.
  2. Under the keycloaktcdemo realm, create a client with the following settings:
    • Client ID: product-service
    • Client Authentication: On
    • Authentication flow: select only Service accounts roles
  3. On the Client details screen, go to the Credentials tab and copy the Client secret value.

Export the realm configuration:

$ docker ps
# copy the keycloak container id

$ docker exec -it <container-id> /bin/bash

$ /opt/keycloak/bin/kc.sh export --dir /opt/keycloak/data/import --realm keycloaktcdemo

$ exit

$ docker cp <container-id>:/opt/keycloak/data/import/keycloaktcdemo-realm.json keycloaktcdemo-realm.json

Copy the exported keycloaktcdemo-realm.json file into src/test/resources.

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