Flink任务提交源码阅读（二）：入口类CliFrontend

柔情只为你懂 2023-06-14 13:56 4阅读 0赞

### 文章目录 ###

*  1.入口类逻辑
 *  2.细节分析
 *   *  2.1打印基本的环境信息
     *  2.2 获取flink配置文件目录
     *  2.3 加载/解析flink-conf.yaml
     *  2.4 加载自定义命令行
     *   *  添加yarn模式命令行
         *  添加默认模式命令行
     *  2.5 初始化CliFrontend对象
     *  2.6 加载安全配置模块
     *   *  SecurityConfiguration初始化
         *  SecurityUtils的install逻辑
     *  2.7 执行对应的action、回调，并返回状态码
     *  2.8 获取执行返回状态码，关闭提交程序

接着上一章的内容，今天继续阅读Flink1.9.0任务提交源码的入口类： **org.apache.flink.client.cli.CliFrontend**  
上篇文章： [Flink1.9.0任务提交源码阅读（一）：flink脚本][Flink1.9.0_flink]  
下一篇： [Flink1.9.0任务提交源码阅读（三）：Job提交 run()][Flink1.9.0_Job_ run]

# 1.入口类逻辑 #

从main()开始，直接上代码

/** Submits the job based on the arguments. */
      public static void main(final String[] args) { 
        // 1.打印基本的环境信息
        EnvironmentInformation.logEnvironmentInfo(LOG, "Command Line Client", args);
    
        // 2. find the configuration directory -- 获取配置文件目录：.../flink1.9.0/conf
        final String configurationDirectory = getConfigurationDirectoryFromEnv();
    
        // 3. load the global configuration -- 加载flink-conf.yaml中的全局配置转成Configuration对象
        final Configuration configuration =
            GlobalConfiguration.loadConfiguration(configurationDirectory);
    
        // 4. load the custom command lines -- 加载用户输入的命令行、获取命令行参数
        final List<CustomCommandLine<?>> customCommandLines =
            loadCustomCommandLines(configuration, configurationDirectory);
    
        try { 
          //5.创建CliFrontend对象
          final CliFrontend cli = new CliFrontend(configuration, customCommandLines);
          //6.加载 SecurityConfiguration类，是flink全局安全配置
          SecurityUtils.install(new SecurityConfiguration(cli.configuration));
          //7.根据命令行参数进行匹配，运行程序，获取程序执行的运行码
          //调用CliFrontend的parseParameters方法， 解析命令行参数，运行具体的action
          int retCode = SecurityUtils.getInstalledContext().runSecured(() -> cli.parseParameters(args));
          //8.获取执行返回值，关闭提交程序
          System.exit(retCode);
        } catch (Throwable t) { 
          final Throwable strippedThrowable =
              ExceptionUtils.stripException(t, UndeclaredThrowableException.class);
          LOG.error("Fatal error while running command line interface.", strippedThrowable);
          strippedThrowable.printStackTrace();
          System.exit(31);
        }
      }

主函数接收命令行传过来的参数，做了一下几个操作：  
1.打印基本的环境信息  
2.调用getConfigurationDirectoryFromEnv方法，根据环境变量FLINK\_CONF\_DIR获取flink配置文件目录  
3.调用GlobalConfiguration的loadConfiguration方法加载flink配置文件flink-conf.yaml中的配置，解析后转成Configuration对象  
4.调用loadCustomCommandLines方法，加载自定义命令行(包含yarn模式命令行和默认命令行两种）  
5.初始化CliFrontend对象  
6.调用SecurityUtils.install方法，加载安全配置模块  
7.根据命令行参数进行Switch case 匹配，执行对应的action、回调，并返回状态码。这块是主要逻辑  
8.获取执行返回状态码，关闭提交程序

# 2.细节分析 #

## 2.1打印基本的环境信息 ##

/** * Logs information about the environment, like code revision, current user, Java version, * and JVM parameters. * * @param log The logger to log the information to. * @param componentName The component name to mention in the log. * @param commandLineArgs The arguments accompanying the starting the component. */
    	public static void logEnvironmentInfo(Logger log, String componentName, String[] commandLineArgs) { 
    		if (log.isInfoEnabled()) { 
    			// 得到代码git的最终提交id和日期
    	        RevisionInformation rev = getRevisionInformation();
    	        // 代码版本
    	        String version = getVersion();
    	        // JVM版本,利用JavaSDK自带的ManagementFactory类来获取。
    	        String jvmVersion = getJvmVersion();
    	        // JVM的启动参数，也是通过JavaSDK自带的ManagementFactory类来获取。
    	        String[] options = getJvmStartupOptionsArray();
    	        // JAVA_Home目录
    	        String javaHome = System.getenv("JAVA_HOME");
    	        // JVM的最大堆内存大小，单位Mb。
    	        long maxHeapMegabytes = getMaxJvmHeapMemory() >>> 20;
    	
    	        // 打印基本信息
    			log.info("--------------------------------------------------------------------------------");
    			log.info(" Starting " + componentName + " (Version: " + version + ", "
    					+ "Rev:" + rev.commitId + ", " + "Date:" + rev.commitDate + ")");
    			log.info(" OS current user: " + System.getProperty("user.name"));
    			log.info(" Current Hadoop/Kerberos user: " + getHadoopUser());
    			log.info(" JVM: " + jvmVersion);
    			log.info(" Maximum heap size: " + maxHeapMegabytes + " MiBytes");
    			log.info(" JAVA_HOME: " + (javaHome == null ? "(not set)" : javaHome));
    			// hadoop的版本信息
    			String hadoopVersionString = getHadoopVersionString();
    			if (hadoopVersionString != null) { 
    				log.info(" Hadoop version: " + hadoopVersionString);
    			} else { 
    				log.info(" No Hadoop Dependency available");
    			}
    			// 打印JVM运行 参数
    			if (options.length == 0) { 
    				log.info(" JVM Options: (none)");
    			}
    			else { 
    				log.info(" JVM Options:");
    				for (String s: options) { 
    					log.info(" " + s);
    				}
    			}
    			// 任务程序启动参数
    			if (commandLineArgs == null || commandLineArgs.length == 0) { 
    				log.info(" Program Arguments: (none)");
    			}
    			else { 
    				log.info(" Program Arguments:");
    				for (String s: commandLineArgs) { 
    					log.info(" " + s);
    				}
    			}
    
    			log.info(" Classpath: " + System.getProperty("java.class.path"));
    
    			log.info("--------------------------------------------------------------------------------");
    		}
    	}

## 2.2 获取flink配置文件目录 ##

调用getConfigurationDirectoryFromEnv方法，根据环境变量FLINK\_CONF\_DIR获取flink配置文件目录

public static String getConfigurationDirectoryFromEnv() { 
        // 获取系统的环境变量FLINK_CONF_DIR，该目录是FLink的配置文件目录
        // 在Flink提交脚本中会调用config.sh脚本，该脚本中会获取Flink的配置目录，并添加到系统环境变量中
        // 这里获取到该目录后，判断该目录是否存在，如果存在则返回Flink配置文件目录路径
        String location = System.getenv(ConfigConstants.ENV_FLINK_CONF_DIR);
    
        if (location != null) { 
          if (new File(location).exists()) { 
            return location;
          } else { 
            throw new RuntimeException(
                "The configuration directory '"
                    + location
                    + "', specified in the '"
                    + ConfigConstants.ENV_FLINK_CONF_DIR
                    + "' environment variable, does not exist.");
          }
        } else if (new File(CONFIG_DIRECTORY_FALLBACK_1).exists()) { 
          location = CONFIG_DIRECTORY_FALLBACK_1;
        } else if (new File(CONFIG_DIRECTORY_FALLBACK_2).exists()) { 
          location = CONFIG_DIRECTORY_FALLBACK_2;
        } else { 
          throw new RuntimeException(
              "The configuration directory was not specified. "
                  + "Please specify the directory containing the configuration file through the '"
                  + ConfigConstants.ENV_FLINK_CONF_DIR
                  + "' environment variable.");
        }
        return location;
      }

## 2.3 加载/解析flink-conf.yaml ##

调用GlobalConfiguration的loadConfiguration方法加载flink配置文件flink-conf.yaml中的配置，解析后转成Configuration对象

/** * Loads the configuration files from the specified directory. * * <p>YAML files are supported as configuration files. * * @param configDir the directory which contains the configuration files */
      public static Configuration loadConfiguration(final String configDir) { 
        return loadConfiguration(configDir, null);
      }

进一步调用loadConfiguration方法：

/** * Loads the configuration files from the specified directory. If the dynamic properties * configuration is not null, then it is added to the loaded configuration. * * @param configDir directory to load the configuration from * @param dynamicProperties configuration file containing the dynamic properties. Null if none. * @return The configuration loaded from the given configuration directory */
      public static Configuration loadConfiguration(
          final String configDir, @Nullable final Configuration dynamicProperties) { 
    
        if (configDir == null) { 
          throw new IllegalArgumentException(
              "Given configuration directory is null, cannot load configuration");
        }
    
        final File confDirFile = new File(configDir);
        if (!(confDirFile.exists())) { 
          throw new IllegalConfigurationException(
              "The given configuration directory name '"
                  + configDir
                  + "' ("
                  + confDirFile.getAbsolutePath()
                  + ") does not describe an existing directory.");
        }
        /** 1.判断配置目录是否为空，不为空获取配置文件，就是flink的配置文件flink-conf.yaml */
        // get Flink yaml configuration file
        final File yamlConfigFile = new File(confDirFile, FLINK_CONF_FILENAME);
    
        if (!yamlConfigFile.exists()) { 
          throw new IllegalConfigurationException(
              "The Flink config file '"
                  + yamlConfigFile
                  + "' ("
                  + confDirFile.getAbsolutePath()
                  + ") does not exist.");
        }
        /** 2.【核心逻辑】获取到文件文件后，调用loadYAMLResource方法，去解析yaml配置文件，并返回HashMap键值对形式的Configuration */
        Configuration configuration = loadYAMLResource(yamlConfigFile);
    
        if (dynamicProperties != null) { 
          configuration.addAll(dynamicProperties);
        }
    
        return enrichWithEnvironmentVariables(configuration);
      }

## 2.4 加载自定义命令行 ##

调用loadCustomCommandLines方法，加载自定义命令行(包含yarn模式命令行和默认命令行两种）  
具体逻辑：

/** * 加载自定义命令行 * @param configuration 配置项 * @param configurationDirectory 配置文件目录 * @return */
    public static List<CustomCommandLine<?>> loadCustomCommandLines(Configuration configuration, String configurationDirectory) { 
        // 1. 初始化一个容量是2的命令栏容器。
        List<CustomCommandLine<?>> customCommandLines = new ArrayList<>(2);
    	 // Command line interface of the YARN session, with a special initialization here
        // to prefix all options with y/yarn.
        // Tips: DefaultCLI must be added at last, because getActiveCustomCommandLine(..) will get the
        // active CustomCommandLine in order and DefaultCLI isActive always return true.
         // 2. YARN会话的命令行接口，所有选项参数都是以y/yarn前缀。
        final String flinkYarnSessionCLI = "org.apache.flink.yarn.cli.FlinkYarnSessionCli";
        try { 
            // 3. 添加yarn模式命令行
            customCommandLines.add(
                loadCustomCommandLine(flinkYarnSessionCLI,
                                      configuration,
                                      configurationDirectory,
                                      "y",
                                      "yarn"));
        } catch (NoClassDefFoundError | Exception e) { 
            LOG.warn("Could not load CLI class {}.", flinkYarnSessionCLI, e);
        }
    
        // 4. 添加默认模式命令行
        customCommandLines.add(new DefaultCLI(configuration));
    
        return customCommandLines;
    }

下面分别展开分析是怎么添加yarn模式命令行和默认模式命令行的。  
yarn模式命令客户端和默认普通模式客户端的类图关系如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzE2MTgxMQ_size_16_color_FFFFFF_t_70]

### 添加yarn模式命令行 ###

/** * 通过反射构建命令行 * @param className 加载的类名全程. * @param params 构建参数 */
    private static CustomCommandLine<?> loadCustomCommandLine(String className, Object... params) throws IllegalAccessException, InvocationTargetException, InstantiationException, ClassNotFoundException, NoSuchMethodException { 
    
        // 1. 加载classpath里相关的类，这个加载的类实现了CustomCommandLine接口
        Class<? extends CustomCommandLine> customCliClass =
            Class.forName(className).asSubclass(CustomCommandLine.class);
    
        // 2. 从参数里构建出参数的Class类型
        Class<?>[] types = new Class<?>[params.length];
        for (int i = 0; i < params.length; i++) { 
            Preconditions.checkNotNull(params[i], "Parameters for custom command-lines may not be null.");
            types[i] = params[i].getClass();
        }
        // 3. 生成构造器org.apache.flink.yarn.cli$FlinkYarnSessionCli
        Constructor<? extends CustomCommandLine> constructor = customCliClass.getConstructor(types);
    
        // 4. 构造器实例化。调用org.apache.flink.yarn.cli$FlinkYarnSessionCli的构造方法，进行实例化。
        return constructor.newInstance(params);
    }

可以看出这里的逻辑是通过FlinkYarnSessionCli的构造器来实例化对象。所以进一步看具体调用了org.apache.flink.yarn.cli$FlinkYarnSessionCli的哪一个构造器，这个是根据构造器的参数决定的。

public FlinkYarnSessionCli(
    	Configuration configuration,
    	String configurationDirectory,
    	String shortPrefix,
    	String longPrefix) throws FlinkException { 
    	  this(configuration, configurationDirectory, shortPrefix, longPrefix, true);
    }

继续调用this(configuration, configurationDirectory, shortPrefix, longPrefix, true)：

/** * 初始化一个FlinkYarnSessionCli * @param configuration 全局的配置 * @param configurationDirectory 全局的配置文件目录 * @param shortPrefix 命令行参数的缩写前缀 * @param longPrefix 命令行参数的展开前缀 * @param acceptInteractiveInput 是否接受交互型输入 * @throws FlinkException */
    public FlinkYarnSessionCli(
        Configuration configuration,
        String configurationDirectory,
        String shortPrefix,
        String longPrefix,
        boolean acceptInteractiveInput) throws FlinkException { 
        // 1. 初始化参数
        super(configuration);
        this.configurationDirectory = Preconditions.checkNotNull(configurationDirectory);
        this.acceptInteractiveInput = acceptInteractiveInput;
    
        // 2. 创建命令行选项
        query = new Option(shortPrefix + "q", longPrefix + "query", false, "Display available YARN resources (memory, cores)");
        applicationId = new Option(shortPrefix + "id", longPrefix + "applicationId", true, "Attach to running YARN session");
        queue = new Option(shortPrefix + "qu", longPrefix + "queue", true, "Specify YARN queue.");
        shipPath = new Option(shortPrefix + "t", longPrefix + "ship", true, "Ship files in the specified directory (t for transfer)");
        flinkJar = new Option(shortPrefix + "j", longPrefix + "jar", true, "Path to Flink jar file");
        jmMemory = new Option(shortPrefix + "jm", longPrefix + "jobManagerMemory", true, "Memory for JobManager Container with optional unit (default: MB)");
        tmMemory = new Option(shortPrefix + "tm", longPrefix + "taskManagerMemory", true, "Memory per TaskManager Container with optional unit (default: MB)");
        container = new Option(shortPrefix + "n", longPrefix + "container", true, "Number of YARN container to allocate (=Number of Task Managers)");
        slots = new Option(shortPrefix + "s", longPrefix + "slots", true, "Number of slots per TaskManager");
        dynamicproperties = Option.builder(shortPrefix + "D")
            .argName("property=value")
            .numberOfArgs(2)
            .valueSeparator()
            .desc("use value for given property")
            .build();
        streaming = new Option(shortPrefix + "st", longPrefix + "streaming", false, "Start Flink in streaming mode");
        name = new Option(shortPrefix + "nm", longPrefix + "name", true, "Set a custom name for the application on YARN");
        zookeeperNamespace = new Option(shortPrefix + "z", longPrefix + "zookeeperNamespace", true, "Namespace to create the Zookeeper sub-paths for high availability mode");
        nodeLabel = new Option(shortPrefix + "nl", longPrefix + "nodeLabel", true, "Specify YARN node label for the YARN application");
        help = new Option(shortPrefix + "h", longPrefix + "help", false, "Help for the Yarn session CLI.");
    
        allOptions = new Options();
        allOptions.addOption(flinkJar);
        allOptions.addOption(jmMemory);
        allOptions.addOption(tmMemory);
        allOptions.addOption(container);
        allOptions.addOption(queue);
        allOptions.addOption(query);
        allOptions.addOption(shipPath);
        allOptions.addOption(slots);
        allOptions.addOption(dynamicproperties);
        allOptions.addOption(DETACHED_OPTION);
        allOptions.addOption(SHUTDOWN_IF_ATTACHED_OPTION);
        allOptions.addOption(YARN_DETACHED_OPTION);
        allOptions.addOption(streaming);
        allOptions.addOption(name);
        allOptions.addOption(applicationId);
        allOptions.addOption(zookeeperNamespace);
        allOptions.addOption(nodeLabel);
        allOptions.addOption(help);
    
        // 3. 加载默认的yarn配置文件
        this.yarnPropertiesFileLocation = configuration.getString(YarnConfigOptions.PROPERTIES_FILE_LOCATION);
        final File yarnPropertiesLocation = getYarnPropertiesLocation(yarnPropertiesFileLocation);
    
        // 4. 解析出yarn的配置参数
        yarnPropertiesFile = new Properties();
    
        if (yarnPropertiesLocation.exists()) { 
            LOG.info("Found Yarn properties file under {}.", yarnPropertiesLocation.getAbsolutePath());
    
            try (InputStream is = new FileInputStream(yarnPropertiesLocation)) { 
                yarnPropertiesFile.load(is);
            } catch (IOException ioe) { 
                throw new FlinkException("Could not read the Yarn properties file " + yarnPropertiesLocation +
                                         ". Please delete the file at " + yarnPropertiesLocation.getAbsolutePath() + '.', ioe);
            }
    
            final String yarnApplicationIdString = yarnPropertiesFile.getProperty(YARN_APPLICATION_ID_KEY);
    
            if (yarnApplicationIdString == null) { 
                throw new FlinkException("Yarn properties file found but doesn't contain a " +
                                         "Yarn application id. Please delete the file at " + yarnPropertiesLocation.getAbsolutePath());
            }
    
            try { 
                // 尝试将id转化成ApplicationId
                yarnApplicationIdFromYarnProperties = ConverterUtils.toApplicationId(yarnApplicationIdString);
            }
            catch (Exception e) { 
                throw new FlinkException("YARN properties contains an invalid entry for " +
                                         "application id: " + yarnApplicationIdString + ". Please delete the file at " +
                                         yarnPropertiesLocation.getAbsolutePath(), e);
            }
        } else { 
            yarnApplicationIdFromYarnProperties = null;
        }
        // 5. 初始化yarn的配置
        this.yarnConfiguration = new YarnConfiguration();
    }

### 添加默认模式命令行 ###

public DefaultCLI(Configuration configuration) { 
    		super(configuration);
    	}

## 2.5 初始化CliFrontend对象 ##

初始化CliFrontend对象

public CliFrontend(
        Configuration configuration,
        List<CustomCommandLine<?>> customCommandLines) throws Exception { 
        // 1. 初始化对象属性判断是否为空
        this.configuration = Preconditions.checkNotNull(configuration);
        this.customCommandLines = Preconditions.checkNotNull(customCommandLines);
    
        try { 
            // 2. 初始化文件系统
            FileSystem.initialize(
            configuration, PluginUtils.createPluginManagerFromRootFolder(configuration));
        } catch (IOException e) { 
            throw new Exception("Error while setting the default " +
                                "filesystem scheme from configuration.", e);
        }
        // 3. 给命令行对象添加选项
        this.customCommandLineOptions = new Options();
    	// 获取用户命令行配置customCommandLines，遍历list将其添加到运行配置和一般配置中
        for (CustomCommandLine<?> customCommandLine : customCommandLines) { 
            customCommandLine.addGeneralOptions(customCommandLineOptions);
            customCommandLine.addRunOptions(customCommandLineOptions);
        }
    
        // 4. 从全局配置里得到akka 客户端等待超时时间（akka.client.timeout）
        this.clientTimeout = AkkaUtils.getClientTimeout(this.configuration);
        // 5. 从全局配置里得到默认的系统并行度
        this.defaultParallelism = configuration.getInteger(CoreOptions.DEFAULT_PARALLELISM);
    }

## 2.6 加载安全配置模块 ##

调用SecurityUtils.install方法，加载安全配置模块  
安装安全机制的逻辑是调用：

SecurityUtils.install(new SecurityConfiguration(cli.configuration));

我们先分析下SecurityConfiguration对象的初始化，然后再分析SecurityUtils的install逻辑。

### SecurityConfiguration初始化 ###

/** * 从全局配置创建安全配置. * @param flinkConf flink全局配置 */
    public SecurityConfiguration(Configuration flinkConf) { 
        this(flinkConf, DEFAULT_MODULES);
    }

其中DEFAULT\_MODULES为默认的安全模板：

// 默认的安全模块
    private static final List<SecurityModuleFactory> DEFAULT_MODULES = Collections.unmodifiableList(
    Arrays.asList(new HadoopModuleFactory(), new JaasModuleFactory(), new ZookeeperModuleFactory()));

继续：

/** * 从全局配置创建安全配置。 * @param flinkConf Flink的全局配置 * @param securityModuleFactories 要应用的安全模块. */
    public SecurityConfiguration(Configuration flinkConf,
    List<SecurityModuleFactory> securityModuleFactories) { 
       // 1. 一些全局参数的配置
        this.isZkSaslDisable = flinkConf.getBoolean(SecurityOptions.ZOOKEEPER_SASL_DISABLE);
        this.keytab = flinkConf.getString(SecurityOptions.KERBEROS_LOGIN_KEYTAB);
        this.principal = flinkConf.getString(SecurityOptions.KERBEROS_LOGIN_PRINCIPAL);
        this.useTicketCache = flinkConf.getBoolean(SecurityOptions.KERBEROS_LOGIN_USETICKETCACHE);
        this.loginContextNames = parseList(flinkConf.getString(SecurityOptions.KERBEROS_LOGIN_CONTEXTS));
        this.zkServiceName = flinkConf.getString(SecurityOptions.ZOOKEEPER_SASL_SERVICE_NAME);
        this.zkLoginContextName = flinkConf.getString(SecurityOptions.ZOOKEEPER_SASL_LOGIN_CONTEXT_NAME);
       
        // 2. 安全模块就是默认的安全模块
        this.securityModuleFactories = Collections.unmodifiableList(securityModuleFactories);
        this.flinkConfig = checkNotNull(flinkConf);
        // 3. 验证
        validate();
    }

进一步看下validate的逻辑：

/** * 验证 */
    private void validate() { 
        if (!StringUtils.isBlank(keytab)) { 
            // principal is required
            if (StringUtils.isBlank(principal)) { 
                throw new IllegalConfigurationException("Kerberos login configuration is invalid; keytab requires a principal.");
            }
    
            // check the keytab is readable
            File keytabFile = new File(keytab);
            if (!keytabFile.exists() || !keytabFile.isFile() || !keytabFile.canRead()) { 
                throw new IllegalConfigurationException("Kerberos login configuration is invalid; keytab is unreadable");
            }
        }
    }

如果全局配置（flink-conf.yaml)里配置了security.kerberos.login.keytab这个参数。那么要校验这个配置所指定的目录存在以及可读。这里其实有必要对kerberos的安全认证相关知识了解下。

### SecurityUtils的install逻辑 ###

SecurityConfiguration对象初始化好之后，作为参数传进SecurityUtils的install方法里面。具体逻辑：

/** * 安装进程范围的安全配置。 * * <p>使用可用的安全模块应用配置 (i.e. Hadoop, JAAS). */
    public static void install(SecurityConfiguration config) throws Exception { 
    
        // 安装安全模块。
        List<SecurityModule> modules = new ArrayList<>();
        try { 
            // 遍历模板，对每个安全模板进行安装。
            for (SecurityModuleFactory moduleFactory : config.getSecurityModuleFactories()) { 
                SecurityModule module = moduleFactory.createModule(config);
                // can be null if a SecurityModule is not supported in the current environment
                if (module != null) { 
                    module.install();
                    modules.add(module);
                }
            }
        }
        catch (Exception ex) { 
            throw new Exception("unable to establish the security context", ex);
        }
        installedModules = modules;
    
        // First check if we have Hadoop in the ClassPath. If not, we simply don't do anything.
        try { 
            Class.forName(
                "org.apache.hadoop.security.UserGroupInformation",
                false,
                SecurityUtils.class.getClassLoader());
    
            // install a security context
            // use the Hadoop login user as the subject of the installed security context
            if (!(installedContext instanceof NoOpSecurityContext)) { 
                LOG.warn("overriding previous security context");
            }
            UserGroupInformation loginUser = UserGroupInformation.getLoginUser();
            installedContext = new HadoopSecurityContext(loginUser);
        } catch (ClassNotFoundException e) { 
            LOG.info("Cannot install HadoopSecurityContext because Hadoop cannot be found in the Classpath.");
        } catch (LinkageError e) { 
            LOG.error("Cannot install HadoopSecurityContext.", e);
        }
    }

这里安装的安全模板主要包括了Java认证与授权服务（JAAS)，Hadoop用户组信息（UGI）和Zookeeper的全过程安全设置。

## 2.7 执行对应的action、回调，并返回状态码 ##

根据命令行参数进行Switch case 匹配，执行对应的action、回调，并返回状态码。

int retCode = SecurityUtils.getInstalledContext()
    					.runSecured(() -> cli.parseParameters(args));

runSecured():

/** * 可能需要具有的安全上下文才能运行可调用的. */
    public interface SecurityContext { 
    
    	<T> T runSecured(Callable<T> securedCallable) throws Exception;
    
    }

具体执行逻辑是cli.parseParameters(args)

/** * 分析命令行参数并启动请求的操作. * * @param args 客户端的命令行参数. * @return 程序的返回状态码 */
    	 public int parseParameters(String[] args) { 
    
        // check for action
        if (args.length < 1) { 
          CliFrontendParser.printHelp(customCommandLines);
          System.out.println("Please specify an action.");
          return 1;
        }
    
        // get action 提取执行动作，比如run,list,cancel
        String action = args[0];
    
        // remove action from parameters 从参数中移除执行动作
        final String[] params = Arrays.copyOfRange(args, 1, args.length);
    
        try { 
          // do action
          switch (action) { 
            case ACTION_RUN:
              run(params);
              return 0;
            case ACTION_LIST:
              list(params);
              return 0;
            case ACTION_INFO:
              info(params);
              return 0;
            case ACTION_CANCEL:
              cancel(params);
              return 0;
            case ACTION_STOP:
              stop(params);
              return 0;
            case ACTION_SAVEPOINT:
              savepoint(params);
              return 0;
            case "-h":
            case "--help":
              CliFrontendParser.printHelp(customCommandLines);
              return 0;
            case "-v":
            case "--version":
              String version = EnvironmentInformation.getVersion();
              String commitID = EnvironmentInformation.getRevisionInformation().commitId;
              System.out.print("Version: " + version);
              System.out.println(
                  commitID.equals(EnvironmentInformation.UNKNOWN) ? "" : ", Commit ID: " + commitID);
              return 0;
            default:
              System.out.printf("\"%s\" is not a valid action.\n", action);
              System.out.println();
              System.out.println(
                  "Valid actions are \"run\", \"list\", \"info\", \"savepoint\", \"stop\", or \"cancel\".");
              System.out.println();
              System.out.println(
                  "Specify the version option (-v or --version) to print Flink version.");
              System.out.println();
              System.out.println("Specify the help option (-h or --help) to get help on the command.");
              return 1;
          }
        } catch (CliArgsException ce) { 
          return handleArgException(ce);
        } catch (ProgramParametrizationException ppe) { 
          return handleParametrizationException(ppe);
        } catch (ProgramMissingJobException pmje) { 
          return handleMissingJobException();
        } catch (Exception e) { 
          return handleError(e);
        }
      }

重点分析下执行任务的逻辑，即执行./flink run的逻辑。这部分比较长，打算另写一篇记录：  
Flink1.9.0任务提交源码阅读（三）：Job提交 run()

## 2.8 获取执行返回状态码，关闭提交程序 ##

获取执行返回状态码，关闭提交程序

--------------------

参考博客：https://blog.csdn.net/hxcaifly/article/details/87864154

[Flink1.9.0_flink]: https://blog.csdn.net/weixin_43161811/article/details/103150383
[Flink1.9.0_Job_ run]: https://blog.csdn.net/weixin_43161811/article/details/103152867
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