Using SpringBootApplication annotation to set a handler in Java

You can set a Java handler by loading a Spring Boot application with an entry point as a class with the SpringBootApplication annotation.

When being executed, the Cloud Functions function has no data about the path that was used to invoke it. In other words, if there is an /api/v1/list endpoint in your Spring Boot application, you will not be able to invoke the function at https://functions.yandexcloud.net/function-id/api/v1/list. Instead, you will have to provide path data in the request body (url parameter) or use API Gateway integration. We recommend the second option because API Gateway is the simplest you can use with a Spring Boot application and enables you to address application endpoints the usual way.

In case your application logic uses the HttpServletRequest and HttpServletResponse classes, please note that Cloud Functions does not support some methods of these classes. You can review the list of unsupported methods here.

Cloud Functions does not support Spring Boot Loader.

Example of a simple application with an endpointExample of a simple application with an endpoint

The following application has a single endpoint: GET: /get/{name}. In response to a GET request at /get with the path parameter specified, the function will return Hello, $name, where $name is the provided path parameter. In our example, we use a public function. If your function is private, specify a service account with the functions.functionInvoker role in the API gateway specification.

1. Create a function.

2. Create a ZIP archive with the following hierarchy:

   src
   |__main
       |__java
           |__util
               |__Application.java
               |__controller
                   |__TestController.java
   pom.xml
   

   • Application.java file:

     package util;
     
     import org.springframework.boot.SpringApplication;
     import org.springframework.boot.autoconfigure.SpringBootApplication;
     
     @SpringBootApplication
     public class Application {
         public static void main(String[] args) {
             SpringApplication.run(Application.class, args);
         }
     }
     

   • TestController.java file:

     package util.controller;
     
     import org.springframework.web.bind.annotation.*;
     
     @RestController
     public class TestController {
         @GetMapping("/get/{name}")
         public String get(@PathVariable String name) {
             return String.format("Hello, %s!", name);
         }
     }
     

   • pom.xml file:

     <?xml version="1.0" encoding="UTF-8"?>
     <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
         <modelVersion>4.0.0</modelVersion>
         <parent>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-parent</artifactId>
             <version>2.4.7</version>
             <relativePath/> <!-- lookup parent from repository -->
         </parent>
     
         <groupId>util</groupId>
         <artifactId>util</artifactId>
         <version>0.0.1-SNAPSHOT</version>
     
         <properties>
             <java.version>11</java.version>
             <spring.version>5.2.9.RELEASE</spring.version>
             <spring.boot.version>2.3.4.RELEASE</spring.boot.version>
             <start-class>util.Application</start-class>
         </properties>
     
         <dependencies>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-starter</artifactId>
                 <version>${spring.boot.version}</version>
             </dependency>
     
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-starter-web</artifactId>
                 <version>${spring.boot.version}</version>
             </dependency>
     
             <dependency>
                 <groupId>javax.servlet</groupId>
                 <artifactId>javax.servlet-api</artifactId>
                 <version>4.0.1</version>
             </dependency>
         </dependencies>
     
         <build>
             <plugins>
                 <plugin>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-maven-plugin</artifactId>
                 </plugin>
             </plugins>
         </build>
     
     </project>
     

3. Create a function version and specify:

   • Runtime environment: java17.
   • Method: ZIP archive.
   • File: Upload the previously created archive.
   • Timeout, sec: 30.
   • Memory: 128 MB.
   • Entry point: util.Application.

4. Create an API Gateway API gateway and add the following specification:

   openapi: 3.0.0
   info:
     title: Test API
     version: 1.0.0
   paths:
     /get/{name}:
       get:
         x-yc-apigateway-integration:
           type: cloud-functions
           function_id: <function_ID>
           service_account_id: <service_account_ID>
         operationId: get
         parameters:
         - description: my param
           explode: false
           in: path
           name: name
           required: true
           schema:
             type: string
           style: simple
   

   Where:

   • function_id: Function ID.
   • service_account_id: Service account with the functions.functionInvoker role.

5. Create a request to the endpoint:

   curl \
     --request GET \
     --header "Authorization: Bearer ${IAM_TOKEN}" \
     https://<gateway_ID>.apigw.yandexcloud.net/get/Anonymous
   

   Result:

   Hello, Anonymous
   

Sample direct request where API Gateway is not used to invoke the function:

{
    "httpMethod": "GET",
    "url": "/get/Anonymous",
    "requestContext": {},
    "body": "",
    "isBase64Encoded": false
}