在基于SpringCloud开发的微服务中，我们一般会选择在网关层记录请求和响应日志，并将其收集到ELK中用作查询和分析。
今天我们就来看看如何实现此功能。
日志实体类
首先我们在网关中定义一个日志实体，用于组装日志对象
@Data
public class AccessLog {
/**用户编号**/
private Long userId;
/**路由**/
private String targetServer;
/**协议**/
private String schema;
/**请求方法名**/
private String requestMethod;
/**访问地址**/
private String requestUrl;
/**请求IP**/
private String clientIp;
/**查询参数**/
private MultiValueMap<String, String> queryParams;
/**请求体**/
private String requestBody;
/**请求头**/
private MultiValueMap<String, String> requestHeaders;
/**响应体**/
private String responseBody;
/**响应头**/
private MultiValueMap<String, String> responseHeaders;
/**响应结果**/
private HttpStatusCode httpStatusCode;
/**开始请求时间**/
private LocalDateTime startTime;
/**结束请求时间**/
private LocalDateTime endTime;
/**执行时长，单位：毫秒**/
private Integer duration;
}网关日志过滤器
接下来我们在网关中定义一个Filter，用于收集日志信息。
@Component
public class AccessLogFilter implements GlobalFilter, Ordered {
private final List<HttpMessageReader<?>> messageReaders = HandlerStrategies.withDefaults().messageReaders();
/**
* 打印日志
* @param accessLog 网关日志
*/
private void writeAccessLog(AccessLog accessLog) {
log.info("----access---- : {}", JsonUtils.obj2StringPretty(accessLog));
}
/**
* 顺序必须是<-1，否则标准的NettyWriteResponseFilter将在您的过滤器得到一个被调用的机会之前发送响应
* 也就是说如果不小于 -1 ，将不会执行获取后端响应的逻辑
* @return
*/
@Override
public int getOrder() {
return -100;
}
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
// 将 Request 中可以直接获取到的参数，设置到网关日志
ServerHttpRequest request = exchange.getRequest();
AccessLog gatewayLog = new AccessLog();
gatewayLog.setTargetServer(WebUtils.getGatewayRoute(exchange).getId());
gatewayLog.setSchema(request.getURI().getScheme());
gatewayLog.setRequestMethod(request.getMethod().name());
gatewayLog.setRequestUrl(request.getURI().getRawPath());
gatewayLog.setQueryParams(request.getQueryParams());
gatewayLog.setRequestHeaders(request.getHeaders());
gatewayLog.setStartTime(LocalDateTime.now());
gatewayLog.setClientIp(WebUtils.getClientIP(exchange));
// 继续 filter 过滤
MediaType mediaType = request.getHeaders().getContentType();
if (MediaType.APPLICATION_FORM_URLENCODED.isCompatibleWith(mediaType)
|| MediaType.APPLICATION_JSON.isCompatibleWith(mediaType)) { // 适合 JSON 和 Form 提交的请求
return filterWithRequestBody(exchange, chain, gatewayLog);
}
return filterWithoutRequestBody(exchange, chain, gatewayLog);
}
/**
* 没有请求体的请求只需要记录日志
*/
private Mono<Void> filterWithoutRequestBody(ServerWebExchange exchange, GatewayFilterChain chain, AccessLog accessLog) {
// 包装 Response，用于记录 Response Body
ServerHttpResponseDecorator decoratedResponse = recordResponseLog(exchange, accessLog);
return chain.filter(exchange.mutate().response(decoratedResponse).build())
.then(Mono.fromRunnable(() -> writeAccessLog(accessLog)));
}
/**
* 需要读取请求体
* 参考 {@link ModifyRequestBodyGatewayFilterFactory} 实现
*/
private Mono<Void> filterWithRequestBody(ServerWebExchange exchange, GatewayFilterChain chain, AccessLog gatewayLog) {
// 设置 Request Body 读取时，设置到网关日志
ServerRequest serverRequest = ServerRequest.create(exchange, messageReaders);
Mono<String> modifiedBody = serverRequest.bodyToMono(String.class).flatMap(body -> {
gatewayLog.setRequestBody(body);
return Mono.just(body);
});
// 通过 BodyInserter 插入 body(支持修改body), 避免 request body 只能获取一次
BodyInserter<Mono<String>, ReactiveHttpOutputMessage> bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class);
HttpHeaders headers = new HttpHeaders();
headers.putAll(exchange.getRequest().getHeaders());
// the new content type will be computed by bodyInserter
// and then set in the request decorator
headers.remove(HttpHeaders.CONTENT_LENGTH);
CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, headers);
// 通过 BodyInserter 将 Request Body 写入到 CachedBodyOutputMessage 中
return bodyInserter.insert(outputMessage, new BodyInserterContext()).then(Mono.defer(() -> {
// 重新封装请求
ServerHttpRequest decoratedRequest = requestDecorate(exchange, headers, outputMessage);
// 记录响应日志
ServerHttpResponseDecorator decoratedResponse = recordResponseLog(exchange, gatewayLog);
// 记录普通的
return chain.filter(exchange.mutate().request(decoratedRequest).response(decoratedResponse).build())
.then(Mono.fromRunnable(() -> writeAccessLog(gatewayLog))); // 打印日志
}));
}
/**
* 记录响应日志
* 通过 DataBufferFactory 解决响应体分段传输问题。
*/
private ServerHttpResponseDecorator recordResponseLog(ServerWebExchange exchange, AccessLog accessLog) {
ServerHttpResponse response = exchange.getResponse();
return new ServerHttpResponseDecorator(response) {
@Override
public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
if (body instanceof Flux) {
DataBufferFactory bufferFactory = response.bufferFactory();
// 计算执行时间
accessLog.setEndTime(LocalDateTime.now());
accessLog.setDuration((int) (LocalDateTimeUtil.between(accessLog.getStartTime(),
accessLog.getEndTime()).toMillis()));
accessLog.setResponseHeaders(response.getHeaders());
accessLog.setHttpStatusCode(response.getStatusCode());
// 获取响应类型，如果是 json 就打印
String originalResponseContentType = exchange.getAttribute(ServerWebExchangeUtils.ORIGINAL_RESPONSE_CONTENT_TYPE_ATTR);
if (StrUtil.isNotBlank(originalResponseContentType)
&& originalResponseContentType.contains("application/json")) {
Flux<? extends DataBuffer> fluxBody = Flux.from(body);
return super.writeWith(fluxBody.buffer().map(dataBuffers -> {
// 设置 response body 到网关日志
byte[] content = readContent(dataBuffers);
String responseResult = new String(content, StandardCharsets.UTF_8);
accessLog.setResponseBody(responseResult);
// 响应
return bufferFactory.wrap(content);
}));
}
}
// if body is not a flux. never got there.
return super.writeWith(body);
}
};
}
/**
* 请求装饰器，支持重新计算 headers、body 缓存
*
* @param exchange 请求
* @param headers 请求头
* @param outputMessage body 缓存
* @return 请求装饰器
*/
private ServerHttpRequestDecorator requestDecorate(ServerWebExchange exchange, HttpHeaders headers, CachedBodyOutputMessage outputMessage) {
return new ServerHttpRequestDecorator(exchange.getRequest()) {
@Override
public HttpHeaders getHeaders() {
long contentLength = headers.getContentLength();
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.putAll(super.getHeaders());
if (contentLength > 0) {
httpHeaders.setContentLength(contentLength);
} else {
// TODO: this causes a 'HTTP/1.1 411 Length Required' // on
// httpbin.org
httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
}
return httpHeaders;
}
@Override
public Flux<DataBuffer> getBody() {
return outputMessage.getBody();
}
};
}
/**
* 从dataBuffers中读取数据
* @author jam
* @date 2024/5/26 22:31
*/
private byte[] readContent(List<? extends DataBuffer> dataBuffers) {
// 合并多个流集合，解决返回体分段传输
DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory();
DataBuffer join = dataBufferFactory.join(dataBuffers);
byte[] content = new byte[join.readableByteCount()];
join.read(content);
// 释放掉内存
DataBufferUtils.release(join);
return content;
}
}代码较长建议直接拷贝到编辑器，只要注意下面一个关键点：
getOrder()方法返回的值必须要<-1，否则标准的NettyWriteResponseFilter将在您的过滤器被调用的机会之前发送响应，即不会执行获取后端响应参数的方法
通过上面的两步我们已经可以获取到请求的输入输出参数了，在 writeAccessLog()中将其打印到日志文件，方便通过ELK进行收集。
在实际项目中，网关日志量一般会非常大，不建议使用数据库进行存储。
实际效果
服务正常响应
服务异常响应