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。
欢迎加入合作群：723288906 免费获取Dubbo、Redis、设计模式、 Netty、zookeeper、Spring cloud、分布式、高并发等架构技术视频资 料,完整架构思维导图，和BATJ面试题及答案。
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。
欢迎加入合作群：723288906 免费获取Dubbo、Redis、设计模式、 Netty、zookeeper、Spring cloud、分布式、高并发等架构技术视频资 料,完整架构思维导图，和BATJ面试题及答案。