本系列代码地址： https://github.com/JoJoTec/spring-cloud-parent
我们这一节在前面实现的带有链路信息的 Publisher 的工厂的基础上，实现公共日志记录的 GlobalFilter。回顾下我们的需求：
我们需要在网关记录每个请求的：
- HTTP 相关元素：
- URL 相关信息
- 请求信息，例如 HTTP HEADER，请求时间等等
- 某些类型的请求体
- 响应信息，例如响应码
- 某些类型响应的响应体
- 链路信息
记录请求与响应的 Body 需要注意的地方
前面的章节我们提到过，对于请求与响应的 body 处理，如果用其结果放入主链路的话，会造成 Spring Cloud Sleuth 的链路信息丢失。还有两个要注意的地方是：
- TCP 粘包拆包导致一个请求体分割成好几份或者一个包包含几个请求
- 读取后要释放原本的请求 body 读取出来的 DataBuffer
为何要释放原本的请求 body 读取出来的 DataBuffer？因为读取出来后占用的 DataBuffer 如果手动不释放那么底层的计数一直不归零会造成内存泄漏。可以参考框架代码看出，这里的 DataBuffer 是需要手动释放的，参考源码：
@Override public ByteBuffer decode(DataBuffer dataBuffer, ResolvableType elementType, @Nullable MimeType mimeType, @Nullable Map<String, Object> hints) { int byteCount = dataBuffer.readableByteCount(); ByteBuffer copy = ByteBuffer.allocate(byteCount); copy.put(dataBuffer.asByteBuffer()); copy.flip(); DataBufferUtils.release(dataBuffer); if (logger.isDebugEnabled()) { logger.debug(Hints.getLogPrefix(hints) + "Read " + byteCount + " bytes"); } return copy; }
我们是想把可以输出到日志的 body 转换成字符串进行输出，为了代码简洁防止出错，我们使用一个工具类来完成将 DataBuffer 读取成字符串并释放的操作：
package com.github.jojotech.spring.cloud.apigateway.common; import com.google.common.base.Charsets; import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBufferUtils; public class BufferUtil { public static String dataBufferToString(DataBuffer dataBuffer) { byte[] content = new byte[dataBuffer.readableByteCount()]; dataBuffer.read(content); DataBufferUtils.release(dataBuffer); return new String(content, Charsets.UTF_8); } }
编写实现公共日志记录 GlobalFilter
前面铺垫了那么多，我们终于可以着手开始写这个日志 GlobalFilter 了：
package com.github.jojotech.spring.cloud.apigateway.filter; import java.net.URI; import java.util.Set; import com.alibaba.fastjson.JSON; import com.github.jojotech.spring.cloud.apigateway.common.BufferUtil; import com.github.jojotech.spring.cloud.apigateway.common.TracedPublisherFactory; import lombok.extern.log4j.Log4j2; import org.reactivestreams.Publisher; import reactor.core.publisher.Flux; import reactor.core.publisher.Mono; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.cloud.gateway.filter.GatewayFilterChain; import org.springframework.cloud.gateway.filter.GlobalFilter; import org.springframework.core.Ordered; import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBufferFactory; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpMethod; import org.springframework.http.MediaType; import org.springframework.http.server.reactive.ServerHttpRequest; import org.springframework.http.server.reactive.ServerHttpRequestDecorator; import org.springframework.http.server.reactive.ServerHttpResponse; import org.springframework.http.server.reactive.ServerHttpResponseDecorator; import org.springframework.stereotype.Component; import org.springframework.web.server.ServerWebExchange; @Log4j2 @Component public class CommonLogFilter implements GlobalFilter, Ordered { //可以输出的 body 格式 public static final Set<MediaType> legalLogMediaTypes = Set.of( MediaType.TEXT_XML, MediaType.TEXT_PLAIN, MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON ); @Autowired private TracedPublisherFactory tracedPublisherFactory; @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { long startTime = System.currentTimeMillis(); ServerHttpRequest request = exchange.getRequest(); ServerHttpResponse response = exchange.getResponse(); //获取用于拆包处理聚合读取请求和响应 body 的 buffer 的 factory DataBufferFactory dataBufferFactory = response.bufferFactory(); //请求 http 头 HttpHeaders requestHeaders = request.getHeaders(); //请求 body 类型 MediaType requestContentType = requestHeaders.getContentType(); //请求 uri String uri = request.getURI().toString(); //请求 http 方法 HttpMethod method = request.getMethod(); log.info("{} -> {}: header: {}", method, uri, JSON.toJSONString(requestHeaders)); Flux<DataBuffer> dataBufferFlux = tracedPublisherFactory.getTracedFlux(request.getBody(), exchange) //使用 buffer 在这里将所有 body 读取完避免拆包影响 .buffer() .map(dataBuffers -> { //将所有 buffer 粘合在一起 DataBuffer dataBuffer = dataBufferFactory.join(dataBuffers); //只有在 debug 开启的时候，才会输出 body if (log.isDebugEnabled()) { //只有特定的 body 类型才会输出具体的 if (legalLogMediaTypes.contains(requestContentType)) { try { //将 body 转化为 String 进行输出，同时注意，原始的 buffer 需要被释放，因为 body 流已经被读取出来，但是没有地方回收 //参考 String s = BufferUtil.dataBufferToString(dataBuffer); log.debug("body: {}", s); dataBuffer = dataBufferFactory.wrap(s.getBytes()); } catch (Exception e) { log.error("error read request body: {}", e.getMessage(), e); } } else { log.debug("body: {}", request); } } return dataBuffer; }); return chain.filter(exchange.mutate().request(new ServerHttpRequestDecorator(request) { @Override public Flux<DataBuffer> getBody() { return dataBufferFlux; } }).response(new ServerHttpResponseDecorator(response) { @Override public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) { HttpHeaders responseHeaders = super.getHeaders(); //调用这里的是写响应回客户端的 HttpClientConnect 的回写，已经跳出了 Spring Cloud Sleuth 的链路 Span，所以没有链路追踪信息 //但是我们在 CommonTraceFilter 我们将链路信息放入了响应 Header 中，所以这里我们就不用手动增加链路信息了 log.info("response: {} -> {} {} header: {}, time: {}ms", method, uri, getStatusCode(), JSON.toJSONString(responseHeaders), System.currentTimeMillis() - startTime); final MediaType contentType = responseHeaders.getContentType(); if (contentType != null && body instanceof Flux && legalLogMediaTypes.contains(contentType) && log.isDebugEnabled()) { //有TCP粘包拆包问题，这个body是多次写入的，一次调用拿不到完整的body，所以这里转换成fluxBody利用其中的buffer来接受完整的body Flux<? extends DataBuffer> fluxBody = tracedPublisherFactory.getTracedFlux(Flux.from(body), exchange); return super.writeWith(fluxBody.buffer().map(buffers -> { DataBuffer buffer = dataBufferFactory.join(buffers); try { String s = BufferUtil.dataBufferToString(buffer); log.debug("response: body: {}", s); return dataBufferFactory.wrap(s.getBytes()); } catch (Exception e) { log.error("error read response body: {}", e.getMessage(), e); } return buffer; })); } // if body is not a flux. never got there. return super.writeWith(body); } }).build()); } @Override public int getOrder() { //指定顺序，在 CommonTraceFilter（这个Filter是读取链路信息，最好在所有 Filter 之前） 之后 return new CommonTraceFilter().getOrder() + 1; } }
需要注意的点都在注释当中明确标出了，请大家参考。
查看日志
我们通过加入下面的日志配置，打开 body 的日志，这样日志就全了：
<AsyncLogger name="com.github.jojotech.spring.cloud.apigateway.filter.CommonLogFilter" level="debug" additivity="false" includeLocation="true"> <appender-ref ref="console" /> </AsyncLogger>
发送一个 POST 带 body 的请求，从日志中就能看到：
2021-11-29 14:08:42,231 INFO [sports,8481ce2786b686fa,8481ce2786b686fa] [24916] [reactor-http-nio-2][com.github.jojotech.spring.cloud.apigateway.filter.CommonLogFilter:59]:POST -> http://127.0.0.1:8181/test-ss/anything?test=1: header: {"Content-Type":["text/plain"],"User-Agent":["PostmanRuntime/7.28.4"],"Accept":["*/*"],"Postman-Token":["666b17c9-0789-46e6-b515-9a4538803308"],"Host":["127.0.0.1:8181"],"Accept-Encoding":["gzip, deflate, br"],"Connection":["keep-alive"],"content-length":["8"]} 2021-11-29 14:08:42,233 DEBUG [sports,8481ce2786b686fa,8481ce2786b686fa] [24916] [reactor-http-nio-2][com.github.jojotech.spring.cloud.apigateway.filter.CommonLogFilter:74]:body: ifasdasd 2021-11-29 14:08:42,463 INFO [sports,,] [24916] [reactor-http-nio-2][com.github.jojotech.spring.cloud.apigateway.filter.CommonLogFilter$1:96]:response: POST -> http://127.0.0.1:8181/test-ss/anything?test=1 200 OK header: {"traceId":["8481ce2786b686fa"],"spanId":["8481ce2786b686fa"],"Date":["Mon, 29 Nov 2021 14:08:43 GMT"],"Content-Type":["application/json"],"Server":["gunicorn/19.9.0"],"Access-Control-Allow-Origin":["*"],"Access-Control-Allow-Credentials":["true"],"content-length":["886"]}, time: 232ms 2021-11-29 14:08:42,466 DEBUG [sports,8481ce2786b686fa,8481ce2786b686fa] [24916] [reactor-http-nio-2][com.github.jojotech.spring.cloud.apigateway.filter.CommonLogFilter$1:105]:response: body: { "args": { "test": "1" }, "data": "ifasdasd", "files": {}, "form": {}, "headers": { "Accept": "*/*", "Accept-Encoding": "gzip, deflate, br", "Content-Length": "8", "Content-Type": "text/plain", "Forwarded": "proto=http;host=\"127.0.0.1:8181\";for=\"127.0.0.1:57526\"", "Host": "httpbin.org", "Postman-Token": "666b17c9-0789-46e6-b515-9a4538803308", "User-Agent": "PostmanRuntime/7.28.4", "X-Amzn-Trace-Id": "Root=1-61a4deeb-3d016ff729306d862edcca0b", "X-B3-Parentspanid": "8481ce2786b686fa", "X-B3-Sampled": "0", "X-B3-Spanid": "5def545b28a7a842", "X-B3-Traceid": "8481ce2786b686fa", "X-Forwarded-Host": "127.0.0.1:8181", "X-Forwarded-Prefix": "/test-ss" }, "json": null, "method": "POST", "origin": "127.0.0.1, 61.244.202.46", "url": "http://127.0.0.1:8181/anything?test=1" } 2021-11-29 14:08:42,474 INFO [sports,,] [24916] [reactor-http-nio-2][reactor.util.Logge
