聊聊nacos的DistroFilter
- 2019 年 10 月 4 日
- 筆記
序
本文主要研究一下nacos的DistroFilter
CanDistro
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/web/CanDistro.java
@Retention(RetentionPolicy.RUNTIME) public @interface CanDistro { }
- CanDistro用于标识一个方法需要判断是否应该根据distro被重定向
DistroFilter
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/web/DistroFilter.java
public class DistroFilter implements Filter { private static final int PROXY_CONNECT_TIMEOUT = 2000; private static final int PROXY_READ_TIMEOUT = 2000; @Autowired private DistroMapper distroMapper; @Autowired private SwitchDomain switchDomain; @Autowired private FilterBase filterBase; @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { HttpServletRequest req = (HttpServletRequest) servletRequest; HttpServletResponse resp = (HttpServletResponse) servletResponse; String urlString = req.getRequestURI(); if (StringUtils.isNotBlank(req.getQueryString())) { urlString += "?" + req.getQueryString(); } try { String path = new URI(req.getRequestURI()).getPath(); String serviceName = req.getParameter(CommonParams.SERVICE_NAME); // For client under 0.8.0: if (StringUtils.isBlank(serviceName)) { serviceName = req.getParameter("dom"); } Method method = filterBase.getMethod(req.getMethod(), path); if (method == null) { throw new NoSuchMethodException(req.getMethod() + " " + path); } String groupName = req.getParameter(CommonParams.GROUP_NAME); if (StringUtils.isBlank(groupName)) { groupName = Constants.DEFAULT_GROUP; } // use groupName@@serviceName as new service name: String groupedServiceName = serviceName; if (StringUtils.isNotBlank(serviceName) && !serviceName.contains(Constants.SERVICE_INFO_SPLITER)) { groupedServiceName = groupName + Constants.SERVICE_INFO_SPLITER + serviceName; } // proxy request to other server if necessary: if (method.isAnnotationPresent(CanDistro.class) && !distroMapper.responsible(groupedServiceName)) { String userAgent = req.getHeader("User-Agent"); if (StringUtils.isNotBlank(userAgent) && userAgent.contains(UtilsAndCommons.NACOS_SERVER_HEADER)) { // This request is sent from peer server, should not be redirected again: Loggers.SRV_LOG.error("receive invalid redirect request from peer {}", req.getRemoteAddr()); resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "receive invalid redirect request from peer " + req.getRemoteAddr()); return; } List<String> headerList = new ArrayList<>(16); Enumeration<String> headers = req.getHeaderNames(); while (headers.hasMoreElements()) { String headerName = headers.nextElement(); headerList.add(headerName); headerList.add(req.getHeader(headerName)); } HttpClient.HttpResult result = HttpClient.request("http://" + distroMapper.mapSrv(groupedServiceName) + urlString, headerList, StringUtils.isBlank(req.getQueryString()) ? HttpClient.translateParameterMap(req.getParameterMap()) : new HashMap<>(2) , PROXY_CONNECT_TIMEOUT, PROXY_READ_TIMEOUT, "UTF-8", req.getMethod()); try { resp.setCharacterEncoding("UTF-8"); resp.getWriter().write(result.content); resp.setStatus(result.code); } catch (Exception ignore) { Loggers.SRV_LOG.warn("[DISTRO-FILTER] request failed: " + distroMapper.mapSrv(groupedServiceName) + urlString); } return; } OverrideParameterRequestWrapper requestWrapper = OverrideParameterRequestWrapper.buildRequest(req); requestWrapper.addParameter(CommonParams.SERVICE_NAME, groupedServiceName); filterChain.doFilter(requestWrapper, resp); } catch (AccessControlException e) { resp.sendError(HttpServletResponse.SC_FORBIDDEN, "access denied: " + UtilsAndCommons.getAllExceptionMsg(e)); return; } catch (NoSuchMethodException e) { resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, "no such api: " + e.getMessage()); return; } catch (Exception e) { resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "Server failed," + UtilsAndCommons.getAllExceptionMsg(e)); return; } } @Override public void destroy() { } }
- DistroFilter实现了servlet的Filter接口；其doFilter方法会从servletRequest中读取serviceName、method、groupName等，然后判断method是否标注CanDistro，如果是而且distroMapper不负责该service则构建http请求然后将结果写回Filter；如果不需要重定向则继续filterChain.doFilter
HttpClient.request
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/misc/HttpClient.java
public class HttpClient { private static final int TIME_OUT_MILLIS = 10000; private static final int CON_TIME_OUT_MILLIS = 5000; private static AsyncHttpClient asyncHttpClient; private static CloseableHttpClient postClient; //...... public static HttpResult request(String url, List<String> headers, Map<String, String> paramValues, int connectTimeout, int readTimeout, String encoding, String method) { HttpURLConnection conn = null; try { String encodedContent = encodingParams(paramValues, encoding); url += (null == encodedContent) ? "" : ("?" + encodedContent); conn = (HttpURLConnection) new URL(url).openConnection(); conn.setConnectTimeout(connectTimeout); conn.setReadTimeout(readTimeout); conn.setRequestMethod(method); conn.addRequestProperty("Client-Version", UtilsAndCommons.SERVER_VERSION); conn.addRequestProperty("User-Agent", UtilsAndCommons.SERVER_VERSION); setHeaders(conn, headers, encoding); conn.connect(); return getResult(conn); } catch (Exception e) { Loggers.SRV_LOG.warn("Exception while request: {}, caused: {}", url, e); return new HttpResult(500, e.toString(), Collections.<String, String>emptyMap()); } finally { if (conn != null) { conn.disconnect(); } } } private static HttpResult getResult(HttpURLConnection conn) throws IOException { int respCode = conn.getResponseCode(); InputStream inputStream; if (HttpURLConnection.HTTP_OK == respCode) { inputStream = conn.getInputStream(); } else { inputStream = conn.getErrorStream(); } Map<String, String> respHeaders = new HashMap<String, String>(conn.getHeaderFields().size()); for (Map.Entry<String, List<String>> entry : conn.getHeaderFields().entrySet()) { respHeaders.put(entry.getKey(), entry.getValue().get(0)); } String gzipEncoding = "gzip"; if (gzipEncoding.equals(respHeaders.get(HttpHeaders.CONTENT_ENCODING))) { inputStream = new GZIPInputStream(inputStream); } HttpResult result = new HttpResult(respCode, IOUtils.toString(inputStream, getCharset(conn)), respHeaders); inputStream.close(); return result; } public static class HttpResult { final public int code; final public String content; final private Map<String, String> respHeaders; public HttpResult(int code, String content, Map<String, String> respHeaders) { this.code = code; this.content = content; this.respHeaders = respHeaders; } public String getHeader(String name) { return respHeaders.get(name); } } //...... }
- HttpClient的request方法直接使用jdk的HttpURLConnection进行请求，返回结果封装为HttpResult，其content即为响应的body
小结
DistroFilter实现了servlet的Filter接口；其doFilter方法会从servletRequest中读取serviceName、method、groupName等，然后判断method是否标注CanDistro，如果是而且distroMapper不负责该service则构建http请求然后将结果写回Filter；如果不需要重定向则继续filterChain.doFilter
doc
- DistroFilter
