zookeeper配置中心实战--solrcloud zookeeper配置中心原理及源码分析

程序的发展，需要引入集中配置：

随着程序功能的日益复杂，程序的配置日益增多：各种功能的开关、参数的配置、服务器的地址…… 并且对配置的期望也越来越高，配置修改后实时生效，灰度发布，分环境、分集群管理配置，完善的权限、审核机制…… 并且随着采用分布式的开发模式，项目之间的相互引用随着服务的不断增多，相互之间的调用复杂度成指数升高，每次投产或者上线新的项目时苦不堪言，因此需要引用配置中心治理。

有哪些开源配置中心

spring-cloud/spring-cloud-config https://github.com/spring-cloud/spring-cloud-config spring出品，可以和spring cloud无缝配合

淘宝 diamond https://github.com/takeseem/diamond 已经不维护

disconf https://github.com/knightliao/disconf java开发，蚂蚁金服技术专家发起，业界使用广泛

ctrip apollo https://github.com/ctripcorp/apollo/ Apollo（阿波罗）是携程框架部门研发的开源配置管理中心，具备规范的权限、流程治理等特性。

配置中心的实现方式可以使用数据库如mysql，可以使用缓存数据如redis，mongodb等，也可以使用zookeeper，zookeeper的watcher特性使它天然具有配置中心的属性。

1.solr zookeeper配置中心搭建(windows环境)

　　1.1 下载solr

　　下载最新的solr https://lucene.apache.org/solr/mirrors-solr-latest-redir.html

　　我此时下载的最新版本为 solr-7.7.0.zip

　　解压到本地目录

　　E:\demo\solr-7.7.0

1.2 启动solr

　　CMD进入bin目录下，执行 solr.cmd start -e cloud

　　 按照提示创建solr cloud实例和分片和collection:

　techproducts

，详细参考官方文档：https://lucene.apache.org/solr/guide/7_6/solr-tutorial.html

　　　回到E:\demo\solr-7.7.0目录，CMD执行导入数据命令：

　　java -jar -Dc=techproducts -Dauto example\exampledocs\post.jar example\exampledocs\*

　 1.3 访问admin

http://localhost:8983

查看内置zookeeper状态

　　创建了一个9983端口的zk实例

1.4 使用ZooInspector监控查看

运行脚本

@echo off cd D:\software\zookeeper-3.4.6\ZooInspector\build d: Java -Dfile.encoding=UTF-8 -jar zookeeper-dev-ZooInspector.jar

2.配置中心文件的上传，下载功能实现

本文仅实现上传功能，下载功能由读者自行实现

2.1 上传配置文件：进入E:\demo\solr-7.7.0/bin目录，CMD执行

solr.cmd zk cp ../LICENSE.txt zk:/test/LICENSE.txt -z localhost:9983 此时在zk下面创建了一个test目录，目录下面有一个license.txt节点，数据即为license.txt文件内容。

2.2 源码分析

用记事本打开solr.cmd命令，找到parse_zk_args参数的地方，发现解析完zk参数就启动了运行zk命令方法run_zk

:run_zk IF "!ZK_OP!"=="" ( set "ERROR_MSG=Invalid command specified for zk sub-command" goto zk_short_usage )

IF "!ZK_HOST!"=="" ( set "ERROR_MSG=Must specify -z zkHost" goto zk_short_usage )

IF "!ZK_OP!"=="-upconfig" ( set ZK_OP="upconfig" ) IF "!ZK_OP!"=="-downconfig" ( set ZK_OP="downconfig" )

IF "!ZK_OP!"=="upconfig" ( IF "!CONFIGSET_NAME!"=="" ( set ERROR_MSG="-n option must be set for upconfig" goto zk_short_usage ) IF "!CONFIGSET_DIR!"=="" ( set ERROR_MSG="The -d option must be set for upconfig." goto zk_short_usage ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%DEFAULT_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -confname !CONFIGSET_NAME! -confdir !CONFIGSET_DIR! -zkHost !ZK_HOST! %ZK_VERBOSE%^ -configsetsDir "%SOLR_TIP%/server/solr/configsets" ) ELSE IF "!ZK_OP!"=="downconfig" ( IF "!CONFIGSET_NAME!"=="" ( set ERROR_MSG="-n option must be set for downconfig" goto zk_short_usage ) IF "!CONFIGSET_DIR!"=="" ( set ERROR_MSG="The -d option must be set for downconfig." goto zk_short_usage ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%DEFAULT_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -confname !CONFIGSET_NAME! -confdir !CONFIGSET_DIR! -zkHost !ZK_HOST! %ZK_VERBOSE% ) ELSE IF "!ZK_OP!"=="cp" ( IF "%ZK_SRC%"=="" ( set ERROR_MSG="<src> must be specified for 'cp' command" goto zk_short_usage ) IF "%ZK_DST%"=="" ( set ERROR_MSG=<dest> must be specified for 'cp' command" goto zk_short_usage ) IF NOT "!ZK_SRC:~0,3!"=="zk:" ( IF NOT "!%ZK_DST:~0,3!"=="zk:" ( set ERROR_MSG="At least one of src or dst must be prefixed by 'zk:'" goto zk_short_usage ) ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%DEFAULT_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -zkHost !ZK_HOST! -src !ZK_SRC! -dst !ZK_DST! -recurse !ZK_RECURSE! %ZK_VERBOSE% ) ELSE IF "!ZK_OP!"=="mv" ( IF "%ZK_SRC%"=="" ( set ERROR_MSG="<src> must be specified for 'mv' command" goto zk_short_usage ) IF "%ZK_DST%"=="" ( set ERROR_MSG="<dest> must be specified for 'mv' command" goto zk_short_usage ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%DEFAULT_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -zkHost !ZK_HOST! -src !ZK_SRC! -dst !ZK_DST! %ZK_VERBOSE% ) ELSE IF "!ZK_OP!"=="rm" ( IF "%ZK_SRC"=="" ( set ERROR_MSG="Zookeeper path to remove must be specified when using the 'rm' command" goto zk_short_usage ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%DEFAULT_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -zkHost !ZK_HOST! -path !ZK_SRC! -recurse !ZK_RECURSE! %ZK_VERBOSE% ) ELSE IF "!ZK_OP!"=="ls" ( IF "%ZK_SRC"=="" ( set ERROR_MSG="Zookeeper path to remove must be specified when using the 'ls' command" goto zk_short_usage ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%DEFAULT_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -zkHost !ZK_HOST! -path !ZK_SRC! -recurse !ZK_RECURSE! %ZK_VERBOSE% ) ELSE IF "!ZK_OP!"=="mkroot" ( IF "%ZK_SRC"=="" ( set ERROR_MSG="Zookeeper path to create must be specified when using the 'mkroot' command" goto zk_short_usage ) "%JAVA%" %SOLR_SSL_OPTS% %AUTHC_OPTS% %SOLR_ZK_CREDS_AND_ACLS% -Dsolr.install.dir="%SOLR_TIP%" ^ -Dlog4j.configurationFile="file:///%SOLR_SERVER_DIR%\resources\log4j2-console.xml" ^ -classpath "%DEFAULT_SERVER_DIR%\solr-webapp\webapp\WEB-INF\lib*;%DEFAULT_SERVER_DIR%\lib\ext*" ^ org.apache.solr.util.SolrCLI !ZK_OP! -zkHost !ZK_HOST! -path !ZK_SRC! %ZK_VERBOSE% ) ELSE ( set ERROR_MSG="Unknown zk option !ZK_OP!" goto zk_short_usage ) goto done 红色即为zk cp命令时执行

org.apache.solr.util.SolrCLI类 不同的命令，使用不同的Tool类

// Creates an instance of the requested tool, using classpath scanning if necessary private static Tool newTool(String toolType) throws Exception { if ("healthcheck".equals(toolType)) return new HealthcheckTool(); else if ("status".equals(toolType)) return new StatusTool(); else if ("api".equals(toolType)) return new ApiTool(); else if ("create_collection".equals(toolType)) return new CreateCollectionTool(); else if ("create_core".equals(toolType)) return new CreateCoreTool(); else if ("create".equals(toolType)) return new CreateTool(); else if ("delete".equals(toolType)) return new DeleteTool(); else if ("config".equals(toolType)) return new ConfigTool(); else if ("run_example".equals(toolType)) return new RunExampleTool(); else if ("upconfig".equals(toolType)) return new ConfigSetUploadTool(); else if ("downconfig".equals(toolType)) return new ConfigSetDownloadTool(); else if ("rm".equals(toolType)) return new ZkRmTool(); else if ("mv".equals(toolType)) return new ZkMvTool(); else if ("cp".equals(toolType)) return new ZkCpTool(); else if ("ls".equals(toolType)) return new ZkLsTool(); else if ("mkroot".equals(toolType)) return new ZkMkrootTool(); else if ("assert".equals(toolType)) return new AssertTool(); else if ("utils".equals(toolType)) return new UtilsTool(); else if ("auth".equals(toolType)) return new AuthTool(); cp执行ZkCpTool的runImpl方法

protected void runImpl(CommandLine cli) throws Exception { raiseLogLevelUnlessVerbose(cli); String zkHost = getZkHost(cli); if (zkHost == null) { throw new IllegalStateException("Solr at " + cli.getOptionValue("solrUrl") + " is running in standalone server mode, cp can only be used when running in SolrCloud mode.\n"); }

try (SolrZkClient zkClient = new SolrZkClient(zkHost, 30000)) { echoIfVerbose("\nConnecting to ZooKeeper at " + zkHost + " ...", cli); String src = cli.getOptionValue("src"); String dst = cli.getOptionValue("dst"); Boolean recurse = Boolean.parseBoolean(cli.getOptionValue("recurse")); echo("Copying from '" + src + "' to '" + dst + "'. ZooKeeper at " + zkHost);

boolean srcIsZk = src.toLowerCase(Locale.ROOT).startsWith("zk:"); boolean dstIsZk = dst.toLowerCase(Locale.ROOT).startsWith("zk:");

String srcName = src; if (srcIsZk) { srcName = src.substring(3); } else if (srcName.toLowerCase(Locale.ROOT).startsWith("file:")) { srcName = srcName.substring(5); }

String dstName = dst; if (dstIsZk) { dstName = dst.substring(3); } else { if (dstName.toLowerCase(Locale.ROOT).startsWith("file:")) { dstName = dstName.substring(5); } } zkClient.zkTransfer(srcName, srcIsZk, dstName, dstIsZk, recurse); } catch (Exception e) { log.error("Could not complete the zk operation for reason: " + e.getMessage()); throw (e); } } 调用SolrZkClient的zkTransfer

public void zkTransfer(String src, Boolean srcIsZk, String dst, Boolean dstIsZk, Boolean recurse) throws SolrServerException, KeeperException, InterruptedException, IOException { ZkMaintenanceUtils.zkTransfer(this, src, srcIsZk, dst, dstIsZk, recurse); } 实现由ZkMaintenanceUtils来做

/**

• Copy between local file system and Zookeeper, or from one Zookeeper node to another,
• optionally copying recursively.
• @param src Source to copy from. Both src and dst may be Znodes. However, both may NOT be local
• @param dst The place to copy the files too. Both src and dst may be Znodes. However both may NOT be local
• @param recurse if the source is a directory, reccursively copy the contents iff this is true.
• @throws SolrServerException Explanatory exception due to bad params, failed operation, etc.
• @throws KeeperException Could not perform the Zookeeper operation.
• @throws InterruptedException Thread interrupted */ public static void zkTransfer(SolrZkClient zkClient, String src, Boolean srcIsZk, String dst, Boolean dstIsZk, Boolean recurse) throws SolrServerException, KeeperException, InterruptedException, IOException {

if (srcIsZk == false && dstIsZk == false) {
  throw new SolrServerException("One or both of source or destination must specify ZK nodes.");
}

// Make sure -recurse is specified if the source has children.
if (recurse == false) {
  if (srcIsZk) {
    if (zkClient.getChildren(src, null, true).size() != 0) {
    throw new SolrServerException("Zookeeper node " + src + " has children and recurse is false");
    }
  } else if (Files.isDirectory(Paths.get(src))) {
  throw new SolrServerException("Local path " + Paths.get(src).toAbsolutePath() + " is a directory and recurse is false");
  }
}

if (dstIsZk && dst.length() == 0) {
  dst = "/"; // for consistency, one can copy from zk: and send to zk:/
}
dst = normalizeDest(src, dst, srcIsZk, dstIsZk);

// ZK -> ZK copy.
if (srcIsZk && dstIsZk) {
  traverseZkTree(zkClient, src, VISIT_ORDER.VISIT_PRE, new ZkCopier(zkClient, src, dst));
  return;
}

//local -> ZK copy
if (dstIsZk) {
  uploadToZK(zkClient, Paths.get(src), dst, null);
  return;
}

// Copying individual files from ZK requires special handling since downloadFromZK assumes the node has children.
// This is kind of a weak test for the notion of "directory" on Zookeeper.
// ZK -> local copy where ZK is a parent node
if (zkClient.getChildren(src, null, true).size() > 0) {
  downloadFromZK(zkClient, src, Paths.get(dst));
  return;
}

// Single file ZK -> local copy where ZK is a leaf node
if (Files.isDirectory(Paths.get(dst))) {
  if (dst.endsWith(File.separator) == false) dst += File.separator;
  dst = normalizeDest(src, dst, srcIsZk, dstIsZk);
}
byte[] data = zkClient.getData(src, null, null, true);
Path filename = Paths.get(dst);
Files.createDirectories(filename.getParent());
log.info("Writing file {}", filename);
Files.write(filename, data);

} 注意：这个copy 可以是本地文件到znode之间的copy，也可以是znode之间的copy

本文以本地文档到znode之间的copy

public static void uploadToZK(SolrZkClient zkClient, final Path fromPath, final String zkPath, final Pattern filenameExclusions) throws IOException {

String path = fromPath.toString(); if (path.endsWith("*")) { path = path.substring(0, path.length() - 1); }

final Path rootPath = Paths.get(path);

if (!Files.exists(rootPath)) throw new IOException("Path " + rootPath + " does not exist");

Files.walkFileTree(rootPath, new SimpleFileVisitor<Path>() { @Override public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException { String filename = file.getFileName().toString(); if (filenameExclusions != null && filenameExclusions.matcher(filename).matches()) { log.info("uploadToZK skipping '{}' due to filenameExclusions '{}'", filename, filenameExclusions); return FileVisitResult.CONTINUE; } String zkNode = createZkNodeName(zkPath, rootPath, file); try { // if the path exists (and presumably we're uploading data to it) just set its data if (file.toFile().getName().equals(ZKNODE_DATA_FILE) && zkClient.exists(zkNode, true)) { zkClient.setData(zkNode, file.toFile(), true); } else { zkClient.makePath(zkNode, file.toFile(), false, true); } } catch (KeeperException | InterruptedException e) { throw new IOException("Error uploading file " + file.toString() + " to zookeeper path " + zkNode, SolrZkClient.checkInterrupted(e)); } return FileVisitResult.CONTINUE; }

@Override public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException { if (dir.getFileName().toString().startsWith(".")) return FileVisitResult.SKIP_SUBTREE;

return FileVisitResult.CONTINUE; } }); } 文件转换为byte流数据，设置到znode

/**

• Write file to ZooKeeper - default system encoding used.
• @param path path to upload file to e.g. /solr/conf/solrconfig.xml
• @param file path to file to be uploaded */ public Stat setData(String path, File file, boolean retryOnConnLoss) throws IOException, KeeperException, InterruptedException { log.debug("Write to ZooKeeper: {} to {}", file.getAbsolutePath(), path); byte[] data = FileUtils.readFileToByteArray(file); return setData(path, data, retryOnConnLoss);

/**

• Returns node's state */ public Stat setData(final String path, final byte data[], final int version, boolean retryOnConnLoss) throws KeeperException, InterruptedException { if (retryOnConnLoss) { return zkCmdExecutor.retryOperation(() -> keeper.setData(path, data, version)); } else { return keeper.setData(path, data, version); } } 具体实现为ZooKeeper本身的客户端ZooKeeper.java

/** * Set the data for the node of the given path if such a node exists and the * given version matches the version of the node (if the given version is * -1, it matches any node's versions). Return the stat of the node. * <p> * This operation, if successful, will trigger all the watches on the node * of the given path left by getData calls. * <p> * A KeeperException with error code KeeperException.NoNode will be thrown * if no node with the given path exists. * <p> * A KeeperException with error code KeeperException.BadVersion will be * thrown if the given version does not match the node's version. * <p> * The maximum allowable size of the data array is 1 MB (1,048,576 bytes). * Arrays larger than this will cause a KeeperException to be thrown. * * @param path * the path of the node * @param data * the data to set * @param version * the expected matching version * @return the state of the node * @throws InterruptedException If the server transaction is interrupted. * @throws KeeperException If the server signals an error with a non-zero error code. * @throws IllegalArgumentException if an invalid path is specified */ public Stat setData(final String path, byte data[], int version) throws KeeperException, InterruptedException { final String clientPath = path; PathUtils.validatePath(clientPath);

    final String serverPath = prependChroot(clientPath);

    RequestHeader h = new RequestHeader();
    h.setType(ZooDefs.OpCode.setData);
    SetDataRequest request = new SetDataRequest();
    request.setPath(serverPath);
    request.setData(data);
    request.setVersion(version);
    SetDataResponse response = new SetDataResponse();
    ReplyHeader r = cnxn.submitRequest(h, request, response, null);
    if (r.getErr() != 0) {
        throw KeeperException.create(KeeperException.Code.get(r.getErr()),
                clientPath);
    }
    return response.getStat();
}

3. 小结

1.solrcloud使用zookeeper实现了配置中心，入口函数为ZkCLI.java ，它使用命令模式内部封装了一系列命令，如：healthcheck，status，api，config，upconfig，downconfig，mv，cp，ls,mkroot等命令

2.最终调用的是apache zookeeper本身的api，如果为文件的话，需要先转为byte流，然后存入znode节点中。

参考文献：

【1】https://www.cnblogs.com/xiaoqi/p/configserver-compair.html

【2】https://lucene.apache.org/solr/guide/7_6/solr-tutorial.html