Luigi Pipeline 从 S3 开始

我的初始文件位于AWS S3。有人能指出我如何在一个Luigi Task?

我查看了文档并发现luigi.S3但我不清楚该怎么办，然后我在网上搜索，只得到链接mortar-luigi并在 luigi 之上实施。

UPDATE

按照为 @matagus 提供的示例（我创建了~/.boto也按照建议文件）：

# coding: utf-8

import luigi

from luigi.s3 import S3Target, S3Client

class MyS3File(luigi.ExternalTask):
    def output(self):
        return S3Target('s3://my-bucket/19170205.txt')

class ProcessS3File(luigi.Task):

    def requieres(self):
        return MyS3File()

    def output(self):
        return luigi.LocalTarget('/tmp/resultado.txt')

    def run(self):
        result = None

        for input in self.input():
           print("Doing something ...")
           with input.open('r') as f:
               for line in f:
                   result = 'This is a line'

        if result:
            out_file = self.output().open('w')
            out_file.write(result)

当我执行它时什么也没有发生

DEBUG: Checking if ProcessS3File() is complete
INFO: Informed scheduler that task   ProcessS3File()   has status   PENDING
INFO: Done scheduling tasks
INFO: Running Worker with 1 processes
DEBUG: Asking scheduler for work...
DEBUG: Pending tasks: 1
INFO: [pid 21171] Worker Worker(salt=226574718, workers=1, host=heliodromus, username=nanounanue, pid=21171) running   ProcessS3File()
INFO: [pid 21171] Worker Worker(salt=226574718, workers=1, host=heliodromus, username=nanounanue, pid=21171) done      ProcessS3File()
DEBUG: 1 running tasks, waiting for next task to finish
INFO: Informed scheduler that task   ProcessS3File()   has status   DONE
DEBUG: Asking scheduler for work...
INFO: Done
INFO: There are no more tasks to run at this time
INFO: Worker Worker(salt=226574718, workers=1, host=heliodromus, username=nanounanue, pid=21171) was stopped. Shutting down Keep-Alive thread

正如您所看到的，该消息Doing something...从不打印。怎么了？

这里的关键是定义一个外部任务没有输入，哪些输出是您在 S3 中已有的文件。 Luigi 文档在中提到了这一点需要另一个任务 http://luigi.readthedocs.org/en/stable/tasks.html#requiring-another-task:

请注意，requires() 不能返回 Target 对象。如果您有一个在外部创建的简单 Target 对象，则可以将其包装在 Task 类中

所以，基本上你最终会得到这样的结果：

import luigi

from luigi.s3 import S3Target

from somewhere import do_something_with


class MyS3File(luigi.ExternalTask):

    def output(self):
        return luigi.S3Target('s3://my-bucket/path/to/file')

class ProcessS3File(luigi.Task):

    def requires(self):
        return MyS3File()

    def output(self):
        return luigi.S3Target('s3://my-bucket/path/to/output-file')

    def run(self):
        result = None
        # this will return a file stream that reads the file from your aws s3 bucket
        with self.input().open('r') as f:
            result = do_something_with(f)

        # and the you 
        out_file = self.output().open('w')
        # it'd better to serialize this result before writing it to a file, but this is a pretty simple example
        out_file.write(result)

UPDATE:

路易吉使用boto http://boto.readthedocs.org/en/latest/从 AWS S3 读取文件和/或将它们写入到 AWS S3，因此为了使此代码正常工作，您需要在 boto 配置文件中提供您的凭据~/boto（寻找其他可能的配置文件位置在这里 http://boto.readthedocs.org/en/latest/boto_config_tut.html):

[Credentials]
aws_access_key_id = <your_access_key_here>
aws_secret_access_key = <your_secret_key_here>