docs: expand Spring Boot skills and add Go microservice example

- springboot-security: add code examples for authorization, input validation, SQL injection prevention, password encoding, CORS, rate limiting, and secrets management (119 → 261 lines) - springboot-verification: add unit test, Testcontainers integration test, MockMvc API test patterns, and security scan grep commands (100 → 222 lines) - Add Go microservice example (gRPC + PostgreSQL + clean architecture) - Update README directory tree with new example
2026-04-09 10:53:34 +08:00 · 2026-02-12 13:36:41 -08:00
parent e1a0700067
commit f375171b13
4 changed files with 534 additions and 2 deletions
--- a/skills/springboot-security/SKILL.md
+++ b/skills/springboot-security/SKILL.md
@@ -42,17 +42,88 @@ public class JwtAuthFilter extends OncePerRequestFilter {
 - Use `@PreAuthorize("hasRole('ADMIN')")` or `@PreAuthorize("@authz.canEdit(#id)")`
 - Deny by default; expose only required scopes

+```java
+@RestController
+@RequestMapping("/api/admin")
+public class AdminController {
+
+  @PreAuthorize("hasRole('ADMIN')")
+  @GetMapping("/users")
+  public List<UserDto> listUsers() {
+    return userService.findAll();
+  }
+
+  @PreAuthorize("@authz.isOwner(#id, authentication)")
+  @DeleteMapping("/users/{id}")
+  public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
+    userService.delete(id);
+    return ResponseEntity.noContent().build();
+  }
+}
+```
+
 ## Input Validation

 - Use Bean Validation with `@Valid` on controllers
 - Apply constraints on DTOs: `@NotBlank`, `@Email`, `@Size`, custom validators
 - Sanitize any HTML with a whitelist before rendering

+```java
+// BAD: No validation
+@PostMapping("/users")
+public User createUser(@RequestBody UserDto dto) {
+  return userService.create(dto);
+}
+
+// GOOD: Validated DTO
+public record CreateUserDto(
+    @NotBlank @Size(max = 100) String name,
+    @NotBlank @Email String email,
+    @NotNull @Min(0) @Max(150) Integer age
+) {}
+
+@PostMapping("/users")
+public ResponseEntity<UserDto> createUser(@Valid @RequestBody CreateUserDto dto) {
+  return ResponseEntity.status(HttpStatus.CREATED)
+      .body(userService.create(dto));
+}
+```
+
 ## SQL Injection Prevention

 - Use Spring Data repositories or parameterized queries
 - For native queries, use `:param` bindings; never concatenate strings

+```java
+// BAD: String concatenation in native query
+@Query(value = "SELECT * FROM users WHERE name = '" + name + "'", nativeQuery = true)
+
+// GOOD: Parameterized native query
+@Query(value = "SELECT * FROM users WHERE name = :name", nativeQuery = true)
+List<User> findByName(@Param("name") String name);
+
+// GOOD: Spring Data derived query (auto-parameterized)
+List<User> findByEmailAndActiveTrue(String email);
+```
+
+## Password Encoding
+
+- Always hash passwords with BCrypt or Argon2 — never store plaintext
+- Use `PasswordEncoder` bean, not manual hashing
+
+```java
+@Bean
+public PasswordEncoder passwordEncoder() {
+  return new BCryptPasswordEncoder(12); // cost factor 12
+}
+
+// In service
+public User register(CreateUserDto dto) {
+  String hashedPassword = passwordEncoder.encode(dto.password());
+  return userRepository.save(new User(dto.email(), hashedPassword));
+}
+```
+
 ## CSRF Protection

 - For browser session apps, keep CSRF enabled; include token in forms/headers
@@ -70,6 +141,25 @@ http
 - Keep `application.yml` free of credentials; use placeholders
 - Rotate tokens and DB credentials regularly

+```yaml
+# BAD: Hardcoded in application.yml
+spring:
+  datasource:
+    password: mySecretPassword123
+
+# GOOD: Environment variable placeholder
+spring:
+  datasource:
+    password: ${DB_PASSWORD}
+
+# GOOD: Spring Cloud Vault integration
+spring:
+  cloud:
+    vault:
+      uri: https://vault.example.com
+      token: ${VAULT_TOKEN}
+```
+
 ## Security Headers

 ```java
@@ -82,11 +172,63 @@ http
    .referrerPolicy(rp -> rp.policy(ReferrerPolicyHeaderWriter.ReferrerPolicy.NO_REFERRER)));
 ```

+## CORS Configuration
+
+- Configure CORS at the security filter level, not per-controller
+- Restrict allowed origins — never use `*` in production
+
+```java
+@Bean
+public CorsConfigurationSource corsConfigurationSource() {
+  CorsConfiguration config = new CorsConfiguration();
+  config.setAllowedOrigins(List.of("https://app.example.com"));
+  config.setAllowedMethods(List.of("GET", "POST", "PUT", "DELETE"));
+  config.setAllowedHeaders(List.of("Authorization", "Content-Type"));
+  config.setAllowCredentials(true);
+  config.setMaxAge(3600L);
+
+  UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
+  source.registerCorsConfiguration("/api/**", config);
+  return source;
+}
+
+// In SecurityFilterChain:
+http.cors(cors -> cors.configurationSource(corsConfigurationSource()));
+```
+
 ## Rate Limiting

 - Apply Bucket4j or gateway-level limits on expensive endpoints
 - Log and alert on bursts; return 429 with retry hints

+```java
+// Using Bucket4j for per-endpoint rate limiting
+@Component
+public class RateLimitFilter extends OncePerRequestFilter {
+  private final Map<String, Bucket> buckets = new ConcurrentHashMap<>();
+
+  private Bucket createBucket() {
+    return Bucket.builder()
+        .addLimit(Bandwidth.classic(100, Refill.intervally(100, Duration.ofMinutes(1))))
+        .build();
+  }
+
+  @Override
+  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
+      FilterChain chain) throws ServletException, IOException {
+    String clientIp = request.getRemoteAddr();
+    Bucket bucket = buckets.computeIfAbsent(clientIp, k -> createBucket());
+
+    if (bucket.tryConsume(1)) {
+      chain.doFilter(request, response);
+    } else {
+      response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
+      response.getWriter().write("{\"error\": \"Rate limit exceeded\"}");
+    }
+  }
+}
+```
+
 ## Dependency Security

 - Run OWASP Dependency Check / Snyk in CI
--- a/skills/springboot-verification/SKILL.md
+++ b/skills/springboot-verification/SKILL.md
@@ -42,6 +42,111 @@ Report:
 - Total tests, passed/failed
 - Coverage % (lines/branches)

+### Unit Tests
+
+Test service logic in isolation with mocked dependencies:
+
+```java
+@ExtendWith(MockitoExtension.class)
+class UserServiceTest {
+
+  @Mock private UserRepository userRepository;
+  @InjectMocks private UserService userService;
+
+  @Test
+  void createUser_validInput_returnsUser() {
+    var dto = new CreateUserDto("Alice", "alice@example.com");
+    var expected = new User(1L, "Alice", "alice@example.com");
+    when(userRepository.save(any(User.class))).thenReturn(expected);
+
+    var result = userService.create(dto);
+
+    assertThat(result.name()).isEqualTo("Alice");
+    verify(userRepository).save(any(User.class));
+  }
+
+  @Test
+  void createUser_duplicateEmail_throwsException() {
+    var dto = new CreateUserDto("Alice", "existing@example.com");
+    when(userRepository.existsByEmail(dto.email())).thenReturn(true);
+
+    assertThatThrownBy(() -> userService.create(dto))
+        .isInstanceOf(DuplicateEmailException.class);
+  }
+}
+```
+
+### Integration Tests with Testcontainers
+
+Test against a real database instead of H2:
+
+```java
+@SpringBootTest
+@Testcontainers
+class UserRepositoryIntegrationTest {
+
+  @Container
+  static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:16-alpine")
+      .withDatabaseName("testdb");
+
+  @DynamicPropertySource
+  static void configureProperties(DynamicPropertyRegistry registry) {
+    registry.add("spring.datasource.url", postgres::getJdbcUrl);
+    registry.add("spring.datasource.username", postgres::getUsername);
+    registry.add("spring.datasource.password", postgres::getPassword);
+  }
+
+  @Autowired private UserRepository userRepository;
+
+  @Test
+  void findByEmail_existingUser_returnsUser() {
+    userRepository.save(new User("Alice", "alice@example.com"));
+
+    var found = userRepository.findByEmail("alice@example.com");
+
+    assertThat(found).isPresent();
+    assertThat(found.get().getName()).isEqualTo("Alice");
+  }
+}
+```
+
+### API Tests with MockMvc
+
+Test controller layer with full Spring context:
+
+```java
+@WebMvcTest(UserController.class)
+class UserControllerTest {
+
+  @Autowired private MockMvc mockMvc;
+  @MockBean private UserService userService;
+
+  @Test
+  void createUser_validInput_returns201() throws Exception {
+    var user = new UserDto(1L, "Alice", "alice@example.com");
+    when(userService.create(any())).thenReturn(user);
+
+    mockMvc.perform(post("/api/users")
+            .contentType(MediaType.APPLICATION_JSON)
+            .content("""
+                {"name": "Alice", "email": "alice@example.com"}
+                """))
+        .andExpect(status().isCreated())
+        .andExpect(jsonPath("$.name").value("Alice"));
+  }
+
+  @Test
+  void createUser_invalidEmail_returns400() throws Exception {
+    mockMvc.perform(post("/api/users")
+            .contentType(MediaType.APPLICATION_JSON)
+            .content("""
+                {"name": "Alice", "email": "not-an-email"}
+                """))
+        .andExpect(status().isBadRequest());
+  }
+}
+```
+
 ## Phase 4: Security Scan

 ```bash
@@ -50,10 +155,27 @@ mvn org.owasp:dependency-check-maven:check
 # or
 ./gradlew dependencyCheckAnalyze

-# Secrets (git)
+# Secrets in source
+grep -rn "password\s*=\s*\"" src/ --include="*.java" --include="*.yml" --include="*.properties"
+grep -rn "sk-\|api_key\|secret" src/ --include="*.java" --include="*.yml"
+
+# Secrets (git history)
 git secrets --scan  # if configured
 ```

+### Common Security Findings
+
+```
+# Check for System.out.println (use logger instead)
+grep -rn "System\.out\.print" src/main/ --include="*.java"
+
+# Check for raw exception messages in responses
+grep -rn "e\.getMessage()" src/main/ --include="*.java"
+
+# Check for wildcard CORS
+grep -rn "allowedOrigins.*\*" src/main/ --include="*.java"
+```
+
 ## Phase 5: Lint/Format (optional gate)

 ```bash