{"id":3647,"date":"2025-12-24T10:00:59","date_gmt":"2025-12-24T15:00:59","guid":{"rendered":"https:\/\/www.mymiller.name\/wordpress\/?p=3647"},"modified":"2025-12-24T10:00:59","modified_gmt":"2025-12-24T15:00:59","slug":"centralized-api-documentation-with-spring-gateway-and-springdoc","status":"publish","type":"post","link":"https:\/\/www.mymiller.name\/wordpress\/spring\/centralized-api-documentation-with-spring-gateway-and-springdoc\/","title":{"rendered":"Centralized API Documentation with Spring Gateway and Springdoc"},"content":{"rendered":"\n<div class=\"wp-block-jetpack-markdown\"><p>In microservices architectures, where multiple services expose their own APIs, having centralized documentation is crucial for developers and consumers.  Spring Gateway, acting as the API gateway, can be leveraged to aggregate and present documentation from various services in a unified manner using Springdoc. Let\u2019s explore how to achieve this.<\/p>\n<h3>Prerequisites<\/h3>\n<ul>\n<li>A working Spring Cloud Gateway project.<\/li>\n<li>Springdoc enabled in your microservices.<\/li>\n<\/ul>\n<h3>Steps<\/h3>\n<ol>\n<li>\n<p><strong>Configure Springdoc in Microservices<\/strong><\/p>\n<p>Ensure each microservice has Springdoc integrated to generate OpenAPI specifications. Include the necessary dependencies and configure basic properties if needed.<\/p>\n<\/li>\n<li>\n<p><strong>Enable Springdoc Gateway Support<\/strong><\/p>\n<p>In your Spring Gateway project, add the <code>springdoc-openapi-webflux-ui<\/code> dependency.<\/p>\n<pre><code class=\"language-xml\">&lt;dependency&gt;\n    &lt;groupId&gt;org.springdoc&lt;\/groupId&gt;\n    &lt;artifactId&gt;springdoc-openapi-webflux-ui&lt;\/artifactId&gt;\n    &lt;version&gt;1.6.15&lt;\/version&gt; \n&lt;\/dependency&gt;\n<\/code><\/pre>\n<\/li>\n<li>\n<p><strong>Configure Gateway Routes<\/strong><\/p>\n<p>Define routes in your gateway to forward requests to the appropriate microservices and their associated documentation endpoints.<\/p>\n<pre><code class=\"language-yaml\">spring:\n  cloud:\n    gateway:\n      routes:\n        - id: service-a\n          uri: lb:\/\/service-a # Replace with your service's URI\n          predicates:\n            - Path=\/service-a\/**\n          filters:\n            - RewritePath=\/service-a\/(?&lt;path&gt;.*), \/$\\{path}\n        # Add routes for other services similarly\n<\/code><\/pre>\n<\/li>\n<li>\n<p><strong>Access the Centralized Documentation<\/strong><\/p>\n<p>Start your Spring Gateway and microservices. Navigate to <code>http:\/\/localhost:8080\/swagger-ui.html<\/code> (adjust the port if necessary) in your browser. You should see a combined documentation page listing APIs from all registered microservices.<\/p>\n<\/li>\n<\/ol>\n<h3>Documenting APIs in Code<\/h3>\n<p>Springdoc leverages annotations to enrich your API documentation directly within your code. Here\u2019s how to use some common annotations:<\/p>\n<ul>\n<li><code>@Operation<\/code>: Describes an API operation, providing a summary, description, and tags for categorization.<\/li>\n<li><code>@Parameter<\/code>: Documents parameters of an operation, specifying their name, description, required status, and data type.<\/li>\n<li><code>@ApiResponse<\/code>: Describes possible responses of an operation, including status codes, descriptions, and associated data models.<\/li>\n<li><code>@Tag<\/code>:  Groups related operations together under a specific tag.<\/li>\n<\/ul>\n<p><strong>Example:<\/strong><\/p>\n<pre><code class=\"language-java\">@RestController\n@RequestMapping(&quot;\/products&quot;)\n@Tag(name = &quot;Product Management&quot;, description = &quot;Operations related to product management&quot;)\npublic class ProductController {\n\n    @GetMapping(&quot;\/{id}&quot;)\n    @Operation(summary = &quot;Get product by ID&quot;, description = &quot;Retrieves product details based on ID&quot;)\n    @ApiResponse(responseCode = &quot;200&quot;, description = &quot;Product found&quot;)\n    @ApiResponse(responseCode = &quot;404&quot;, description = &quot;Product not found&quot;)\n    public Product getProductById(@PathVariable @Parameter(description = &quot;Product ID&quot;) Long id) {\n        \/\/ ... implementation\n    }\n\n    \/\/ Other endpoints with similar annotations\n}\n<\/code><\/pre>\n<h3>Leveraging <code>@Schema<\/code> for Model Documentation<\/h3>\n<p>The <code>@Schema<\/code> annotation provides detailed information about data models used in your APIs, making your documentation even more comprehensive. Apply it to classes and fields to describe their properties:<\/p>\n<pre><code class=\"language-java\">public class Product {\n\n    @Schema(description = &quot;Unique identifier of the product&quot;)\n    private Long id;\n\n    @Schema(description = &quot;Name of the product&quot;)\n    private String name;\n\n    @Schema(description = &quot;Price of the product&quot;)\n    private BigDecimal price;\n\n    \/\/ ... other fields and methods\n}\n<\/code><\/pre>\n<h3>Key Points and Considerations<\/h3>\n<ul>\n<li>Springdoc\u2019s auto-configuration makes setup fairly simple.<\/li>\n<li>Gateway routes are critical for directing requests to the correct services and their documentation.<\/li>\n<li>For more complex setups, consider using <code>GroupedOpenApi<\/code> to organize APIs within the combined documentation.<\/li>\n<li>Ensure version compatibility between Springdoc and Spring Cloud Gateway.<\/li>\n<li>Use annotations judiciously to provide clear and informative documentation.<\/li>\n<li><code>@Schema<\/code> enhances your documentation by providing details about data models.<\/li>\n<\/ul>\n<p><strong>Conclusion<\/strong><\/p>\n<p>Centralized documentation using Spring Gateway and Springdoc provides a streamlined way to understand and interact with your microservices\u2019 APIs. By combining documentation from various services into a single view, you enhance developer experience and simplify API consumption. Documenting APIs within your code using annotations further improves clarity and maintainability. The <code>@Schema<\/code> annotation adds an extra layer of detail by describing data models.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":3649,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[318],"tags":[69,319],"series":[],"class_list":["post-3647","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-spring","tag-java-2","tag-spring"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.mymiller.name\/wordpress\/wp-content\/uploads\/2024\/08\/library-488683_1280-jpg.avif","jetpack-related-posts":[{"id":3834,"url":"https:\/\/www.mymiller.name\/wordpress\/spring_rest\/documenting-your-datas-reach-generating-api-docs-for-spring-data-rest\/","url_meta":{"origin":3647,"position":0},"title":"Documenting Your Data&#8217;s Reach: Generating API Docs for Spring Data REST","author":"Jeffery Miller","date":"December 24, 2025","format":false,"excerpt":"Spring Data REST is a fantastic tool for rapidly exposing your JPA entities as hypermedia-driven REST APIs. 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