Feature/min io

core/src/main/java/com/opencontext/common/CommonResponse.java

@@ -82,4 +82,17 @@ public static <T> CommonResponse<T> error(String message, String errorCode) {
                 LocalDateTime.now()
         );
     }
+
+    /**
+     * Static factory method for creating error responses from ErrorCode enum.
+     */
+    public static <T> CommonResponse<T> error(com.opencontext.enums.ErrorCode errorCode, String message) {
+        return new CommonResponse<>(
+                false,
+                null,
+                message,
+                errorCode.getCode(),
+                LocalDateTime.now()
+        );
+    }
 }

core/src/main/java/com/opencontext/config/ApiKeyAuthenticationFilter.java

@@ -0,0 +1,92 @@
+package com.opencontext.config;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.opencontext.common.CommonResponse;
+import com.opencontext.enums.ErrorCode;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Component;
+import org.springframework.util.StringUtils;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Filter for API Key authentication on admin endpoints.
+ * 
+ * This filter validates the X-API-KEY header for endpoints that require
+ * admin access, specifically the document management APIs.
+ */
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class ApiKeyAuthenticationFilter extends OncePerRequestFilter {
+
+    private final ObjectMapper objectMapper;
+
+    @Value("${opencontext.api.key:dev-api-key-123}")
+    private String validApiKey;
+
+    // Endpoints that require API Key authentication
+    private static final List<String> PROTECTED_ENDPOINTS = Arrays.asList(
+            "/api/v1/sources"
+    );
+
+    @Override
+    protected void doFilterInternal(HttpServletRequest request, 
+                                  HttpServletResponse response, 
+                                  FilterChain filterChain) throws ServletException, IOException {
+
+        String requestPath = request.getRequestURI();
+
+        // Check if this endpoint requires API Key authentication
+        boolean requiresAuth = PROTECTED_ENDPOINTS.stream()
+                .anyMatch(requestPath::startsWith);
+
+        if (requiresAuth) {
+            String apiKey = request.getHeader("X-API-KEY");
+
+            if (!StringUtils.hasText(apiKey)) {
+                log.warn("API Key missing for protected endpoint: {}", requestPath);
+                sendErrorResponse(response, ErrorCode.INSUFFICIENT_PERMISSION, 
+                        "API Key is required. Please provide X-API-KEY header.");
+                return;
+            }
+
+            if (!validApiKey.equals(apiKey)) {
+                log.warn("Invalid API Key provided for endpoint: {}", requestPath);
+                sendErrorResponse(response, ErrorCode.INSUFFICIENT_PERMISSION, 
+                        "Invalid API Key provided.");
+                return;
+            }
+
+            log.debug("API Key authentication successful for endpoint: {}", requestPath);
+        }
+
+        filterChain.doFilter(request, response);
+    }
+
+    /**
+     * Sends an error response in JSON format.
+     */
+    private void sendErrorResponse(HttpServletResponse response, ErrorCode errorCode, String message) 
+            throws IOException {
+
+        response.setStatus(errorCode.getHttpStatus().value());
+        response.setContentType(MediaType.APPLICATION_JSON_VALUE);
+        response.setCharacterEncoding("UTF-8");
+
+        CommonResponse<Void> errorResponse = CommonResponse.error(errorCode, message);
+
+        String jsonResponse = objectMapper.writeValueAsString(errorResponse);
+        response.getWriter().write(jsonResponse);
+    }
+}

core/src/main/java/com/opencontext/config/MinIOConfig.java

@@ -0,0 +1,41 @@
+package com.opencontext.config;
+
+import io.minio.MinioClient;
+import lombok.Data;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * MinIO client configuration for object storage operations.
+ * 
+ * This configuration creates a MinIO client bean that can be used throughout
+ * the application for file upload, download, and management operations.
+ */
+@Slf4j
+@Data
+@Configuration
+@ConfigurationProperties(prefix = "minio")
+public class MinIOConfig {
+
+    private String endpoint;
+    private String accessKey;
+    private String secretKey;
+    private String bucketName;
+
+    /**
+     * Creates and configures the MinIO client bean.
+     * 
+     * @return configured MinioClient instance
+     */
+    @Bean
+    public MinioClient minioClient() {
+        log.info("Initializing MinIO client with endpoint: {}", endpoint);
+
+        return MinioClient.builder()
+                .endpoint(endpoint)
+                .credentials(accessKey, secretKey)
+                .build();
+    }
+}

core/src/main/java/com/opencontext/config/SecurityConfig.java

@@ -25,6 +25,7 @@
 public class SecurityConfig {
 
     private final Environment environment;
+    private final ApiKeyAuthenticationFilter apiKeyAuthenticationFilter;
 
     @Bean
     public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
@@ -62,15 +63,15 @@ public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
                 // Allow development mock data endpoints (development only)
                 .requestMatchers("/api/v1/dev/**").permitAll()
 
-                // Admin APIs will require API Key authentication (TODO: implement in next step)
-                .requestMatchers("/api/v1/sources/**").permitAll() // Temporary - will add API key auth
+                // Admin APIs require API Key authentication
+                .requestMatchers("/api/v1/sources/**").permitAll() // Authentication handled by filter
 
                 // All other requests require authentication
                 .anyRequest().authenticated()
             );
 
-        // TODO: Add API Key authentication filter for Admin APIs
-        // http.addFilterBefore(apiKeyAuthenticationFilter, UsernamePasswordAuthenticationFilter.class);
+        // Add API Key authentication filter for Admin APIs
+        http.addFilterBefore(apiKeyAuthenticationFilter, UsernamePasswordAuthenticationFilter.class);
 
         log.info("Security configuration completed successfully");
         return http.build();