21-12-03
banq
在这个微服务世界中，我们总是强调通过 API/服务网关层传递任何 HTTP 请求，该层连接多个微服务，并有一个最低要求，即记录每个服务的所有请求和响应以获得更清晰的可见性。
我们可以考虑在以下场景中编写我们的反向代理层。
- 1.假设具有API服务像“PHP”或“Python”等另一种语言，我们需要以部分地变换该请求。
- 2. 添加授权或在服务未能响应请求时实现重试
- 3. 记录所有流经此反向代理层的请求和响应，稍后推送到某些日志记录堆栈，如 ELK
- 4. 为服务传播实现我们的自定义跟踪逻辑.
- 5. 或者重新发明轮子只是为了好玩
在这个示例中，我使用 Springboot 及其嵌入式 Tomcat 服务器。和 Spring Spring retry Dependency 来实现请求失败时的重试逻辑。
Springboot 控制器拦截所有请求并将它们传递给代理服务类：
@RestController
public class ProxyController {
@Autowired
ProxyService service;
@RequestMapping("/**")
public ResponseEntity<String> sendRequestToSPM(@RequestBody(required = false) String body,
HttpMethod method, HttpServletRequest request, HttpServletResponse response)
throws URISyntaxException {
return service.processProxyRequest(body,method,request,response, UUID.randomUUID().toString());
}
}
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ProxySerivce：
当我们收到来自控制器的请求时，Simple RestTemplate 会向所需的域执行 HTTP 请求。这是可以扩展到我们的要求的类，例如执行自定义日志记录，或者在这个例子中实现重试，当 HTTP 调用失败时。
@Service
public class ProxyService {
String domain = "example.com";
private final static Logger logger = LogManager.getLogger(ProxyService.class);
@Retryable(exclude = {
HttpStatusCodeException.class}, include = Exception.class, backoff = @Backoff(delay = 5000, multiplier = 4.0), maxAttempts = 4)
public ResponseEntity<String> processProxyRequest(String body,
HttpMethod method, HttpServletRequest request, HttpServletResponse response, String traceId) throws URISyntaxException {
ThreadContext.put("traceId", traceId);
String requestUrl = request.getRequestURI();
//log if required in this line
URI uri = new URI("https", null, domain, -1, null, null, null);
// replacing context path form urI to match actual gateway URI
uri = UriComponentsBuilder.fromUri(uri)
.path(requestUrl)
.query(request.getQueryString())
.build(true).toUri();
HttpHeaders headers = new HttpHeaders();
Enumeration<String> headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
String headerName = headerNames.nextElement();
headers.set(headerName, request.getHeader(headerName));
}
headers.set("TRACE", traceId);
headers.remove(HttpHeaders.ACCEPT_ENCODING);
HttpEntity<String> httpEntity = new HttpEntity<>(body, headers);
ClientHttpRequestFactory factory = new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory());
RestTemplate restTemplate = new RestTemplate(factory);
try {
ResponseEntity<String> serverResponse = restTemplate.exchange(uri, method, httpEntity, String.class);
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.put(HttpHeaders.CONTENT_TYPE, serverResponse.getHeaders().get(HttpHeaders.CONTENT_TYPE));
logger.info(serverResponse);
return serverResponse;
} catch (HttpStatusCodeException e) {
logger.error(e.getMessage());
return ResponseEntity.status(e.getRawStatusCode())
.headers(e.getResponseHeaders())
.body(e.getResponseBodyAsString());
}
}
@Recover
public ResponseEntity<String> recoverFromRestClientErrors(Exception e, String body,
HttpMethod method, HttpServletRequest request, HttpServletResponse response, String traceId) {
logger.error("retry method for the following url " + request.getRequestURI() + " has failed" + e.getMessage());
logger.error(e.getStackTrace());
throw new RuntimeException("There was an error trying to process you request. Please try again later");
}
}
主类：
@SpringBootApplication
@EnableRetry
public class ProxyAppApplication {
public static void main(String[] args) {
SpringApplication.run(ProxyAppApplication.class, args);
}
}
pom.xml
<?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>2.6.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.ashrithgn.example</groupId>
<artifactId>proxyApp</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>proxyApp</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>17</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.retry</groupId>
<artifactId>spring-retry</artifactId>
<version>1.2.5.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>5.2.8.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
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