目录

一：启动脚本解析

二：源码解析

入口

2.execute()核心方法

一：启动脚本解析

在 /bin/start-seatunnel-flink.sh 

#!/bin/bash

function usage() {
  echo "Usage: start-seatunnel-flink.sh [options]"
  echo "  options:"
  echo "    --config, -c FILE_PATH        Config file"
  echo "    --variable, -i PROP=VALUE     Variable substitution, such as -i city=beijing, or -i date=20190318"
  echo "    --check, -t                   Check config"
  echo "    --help, -h                    Show this help message"
}

if [[ "$@" = *--help ]] || [[ "$@" = *-h ]] || [[ $# -le 1 ]]; then
  usage
  exit 0
fi

is_exist() {
    if [ -z $1 ]; then
      usage
      exit -1
    fi
}

PARAMS=""
while (( "$#" )); do
  case "$1" in
    -c|--config)
      CONFIG_FILE=$2
      is_exist ${CONFIG_FILE}
      shift 2
      ;;

    -i|--variable)
      variable=$2
      is_exist ${variable}
      java_property_value="-D${variable}"
      variables_substitution="${java_property_value} ${variables_substitution}"
      shift 2
      ;;

    *) # preserve positional arguments
      PARAMS="$PARAMS $1"
      shift
      ;;

  esac
done

if [ -z ${CONFIG_FILE} ]; then
  echo "Error: The following option is required: [-c | --config]"
  usage
  exit -1
fi

# set positional arguments in their proper place
eval set -- "$PARAMS"

BIN_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
APP_DIR=$(dirname ${BIN_DIR})
CONF_DIR=${APP_DIR}/config
PLUGINS_DIR=${APP_DIR}/lib
DEFAULT_CONFIG=${CONF_DIR}/application.conf
CONFIG_FILE=${CONFIG_FILE:-$DEFAULT_CONFIG}

assemblyJarName=$(find ${PLUGINS_DIR} -name seatunnel-core-flink*.jar)

if [ -f "${CONF_DIR}/seatunnel-env.sh" ]; then
    source ${CONF_DIR}/seatunnel-env.sh
fi

string_trim() {
    echo $1 | awk '{$1=$1;print}'
}

export JVM_ARGS=$(string_trim "${variables_substitution}")


exec ${FLINK_HOME}/bin/flink run \
    ${PARAMS} \
    -c org.apache.seatunnel.SeatunnelFlink \
    ${assemblyJarName} --config ${CONFIG_FILE}

org.apache.seatunnel.SeatunnelFlink 这个类就是主入口

二：源码解析

1. 入口

public class SeatunnelFlink {

    public static void main(String[] args) throws Exception {
        FlinkCommandArgs flinkArgs = CommandLineUtils.parseFlinkArgs(args);
        Seatunnel.run(flinkArgs);
    }

}

FlinkCommandArgs中进行命令行参数解析

    public static FlinkCommandArgs parseFlinkArgs(String[] args) {
        FlinkCommandArgs flinkCommandArgs = new FlinkCommandArgs();
        JCommander.newBuilder()
            .addObject(flinkCommandArgs)
            .build()
            .parse(args);
        return flinkCommandArgs;
    }

进入到Seatunnel.run(flinkArgs);

    public static <T extends CommandArgs> void run(T commandArgs) {

        if (!Common.setDeployMode(commandArgs.getDeployMode().getName())) {
            throw new IllegalArgumentException(
                String.format("Deploy mode: %s is Illegal", commandArgs.getDeployMode()));
        }

        try {
            Command<T> command = CommandFactory.createCommand(commandArgs);
            command.execute(commandArgs);
        } catch (ConfigRuntimeException e) {
            showConfigError(e);
            throw e;
        } catch (Exception e) {
            showFatalError(e);
            throw e;
        }
    }

进入到CommandFactory.createCommand(commandArgs);，根据不同的类型选择Command，我们看的是flinkCommand。

    public static <T extends CommandArgs> Command<T> createCommand(T commandArgs) {
        switch (commandArgs.getEngineType()) {
            case FLINK:
                return (Command<T>) new FlinkCommandBuilder().buildCommand((FlinkCommandArgs) commandArgs);
            case SPARK:
                return (Command<T>) new SparkCommandBuilder().buildCommand((SparkCommandArgs) commandArgs);
            default:
                throw new RuntimeException(String.format("engine type: %s is not supported", commandArgs.getEngineType()));
        }
    }

进入到 buildCommand，根据是否检查config进入到不同的实现类

    public Command<FlinkCommandArgs> buildCommand(FlinkCommandArgs commandArgs) {
        return commandArgs.isCheckConfig() ? new FlinkConfValidateCommand() : new FlinkTaskExecuteCommand();
    }

FlinkConfValidateCommand和FlinkTaskExecuteCommand两个类都实现了Command类。并且都只有一个execute()方法

public class FlinkConfValidateCommand implements Command<FlinkCommandArgs>
public class FlinkTaskExecuteCommand extends BaseTaskExecuteCommand<FlinkCommandArgs, FlinkEnvironment>

在SeaTunnel.run(flinkArgs)进入  command.execute(commandArgs);

我们先看FlinkTaskExecuteCommand 类中的execute方法

2.execute()核心方法

 public void execute(FlinkCommandArgs flinkCommandArgs) {
        //flink
        EngineType engine = flinkCommandArgs.getEngineType();
        // --config
        String configFile = flinkCommandArgs.getConfigFile();
        //将String变成Config类
        Config config = new ConfigBuilder<>(configFile, engine).getConfig();
        //解析执行上下文
        ExecutionContext<FlinkEnvironment> executionContext = new ExecutionContext<>(config, engine);
        //解析 sources模块
        List<BaseSource<FlinkEnvironment>> sources = executionContext.getSources();
        //解析 tansform模块
        List<BaseTransform<FlinkEnvironment>> transforms = executionContext.getTransforms();
        //解析 sink模块
        List<BaseSink<FlinkEnvironment>> sinks = executionContext.getSinks();

        baseCheckConfig(sinks, transforms, sinks);
        showAsciiLogo();

        try (Execution<BaseSource<FlinkEnvironment>,
                BaseTransform<FlinkEnvironment>,
                BaseSink<FlinkEnvironment>,
                FlinkEnvironment> execution = new ExecutionFactory<>(executionContext).createExecution()) {
            //准备
            prepare(executionContext.getEnvironment(), sources, transforms, sinks);
            //启动
            execution.start(sources, transforms, sinks);
            //关闭
            close(sources, transforms, sinks);
        } catch (Exception e) {
            throw new RuntimeException("Execute Flink task error", e);
        }
    }