如何解决创建Google Dataflow模板文件时出错
我正在尝试使用模板安排在指定时间后结束的数据流。使用命令行时,我能够成功完成此操作,但是当我尝试使用Google Cloud Scheduler进行创建模板时,就会遇到错误。
错误是
File "pipelin_stream.py",line 37,in <module>
main()
File "pipelin_stream.py",line 34,in main
result.cancel()
File "/usr/local/lib/python2.7/dist-packages/apache_beam/runners/dataflow/dataflow_runner.py",line 1638,in cancel
raise IOError('Failed to get the Dataflow job id.')
IOError: Failed to get the Dataflow job id.
我用来制作模板的命令是
python pipelin_stream.py \
--runner Dataflowrunner \
--project $PROJECT \
--temp_location $BUCKET/tmp \
--staging_location $BUCKET/staging \
--template_location $BUCKET/templates/time_template_test \
--streaming
我拥有的管道文件是这个
from apache_beam.options.pipeline_options import PipelineOptions
from google.cloud import pubsub_v1
from google.cloud import bigquery
import apache_beam as beam
import logging
import argparse
import sys
PROJECT = 'projectID'
schema = 'ex1:DATE,ex2:STRING'
TOPIC = "projects/topic-name/topics/scraping-test"
def main(argv=None):
parser = argparse.ArgumentParser()
parser.add_argument("--input_topic")
parser.add_argument("--output")
kNown_args = parser.parse_kNown_args(argv)
p = beam.Pipeline(options=PipelineOptions(region='us-central1',service_account_email='email'))
(p
| 'ReadData' >> beam.io.ReadFrompubSub(topic=TOPIC).with_output_types(bytes)
| 'Decode' >> beam.Map(lambda x:x.decode('utf-8'))
| 'WritetoBigQuery' >> beam.io.WritetoBigQuery('tablename'.format(PROJECT),schema=schema,write_disposition=beam.io.BigQuerydisposition.WRITE_APPEND)
)
result = p.run()
result.wait_until_finish(duration=3000)
result.cancel() # If the pipeline has not finished,you can cancel it
if __name__ == '__main__':
logger = logging.getLogger().setLevel(logging.INFO)
main()
有人知道为什么我会出现此错误吗?
解决方法
等待时间过后,cancel function会引发该错误,并且似乎无害。
为了证明这一点,我设法使用python 3.5从虚拟机中重现了您的确切问题。该模板由--template_location
在给定的路径中创建,可用于运行作业。请注意,我需要对您的代码进行一些更改,以使其在Dataflow中真正起作用。
如果对您有什么用,我最终使用了该管道代码
from apache_beam.options.pipeline_options import PipelineOptions
from google.cloud import pubsub_v1
from google.cloud import bigquery
import apache_beam as beam
import logging
import argparse
import datetime
# Fill this values in order to have them by default
# Note that the table in BQ needs to have the column names message_body and publish_time
Table = 'projectid:datasetid.tableid'
schema = 'ex1:STRING,ex2:TIMESTAMP'
TOPIC = "projects/<projectid>/topics/<topicname>"
class AddTimestamps(beam.DoFn):
def process(self,element,publish_time=beam.DoFn.TimestampParam):
"""Processes each incoming element by extracting the Pub/Sub
message and its publish timestamp into a dictionary. `publish_time`
defaults to the publish timestamp returned by the Pub/Sub server. It
is bound to each element by Beam at runtime.
"""
yield {
"message_body": element.decode("utf-8"),"publish_time": datetime.datetime.utcfromtimestamp(
float(publish_time)
).strftime("%Y-%m-%d %H:%M:%S.%f"),}
def main(argv=None):
parser = argparse.ArgumentParser()
parser.add_argument("--input_topic",default=TOPIC)
parser.add_argument("--output_table",default=Table)
args,beam_args = parser.parse_known_args(argv)
# save_main_session needs to be set to true due to modules being used among the code (mostly datetime)
# Uncomment the service account email to specify a custom service account
p = beam.Pipeline(argv=beam_args,options=PipelineOptions(save_main_session=True,region='us-central1'))#,service_account_email='email'))
(p
| 'ReadData' >> beam.io.ReadFromPubSub(topic=args.input_topic).with_output_types(bytes)
| "Add timestamps to messages" >> beam.ParDo(AddTimestamps())
| 'WriteToBigQuery' >> beam.io.WriteToBigQuery(args.output_table,schema=schema,write_disposition=beam.io.BigQueryDisposition.WRITE_APPEND)
)
result = p.run()
#Warning: Cancel does not work properly in a template
result.wait_until_finish(duration=3000)
result.cancel() # Cancel the streaming pipeline after a while to avoid consuming more resources
if __name__ == '__main__':
logger = logging.getLogger().setLevel(logging.INFO)
main()
然后我运行命令:
# Fill accordingly
PROJECT="MYPROJECT-ID"
BUCKET="MYBUCKET"
TEMPLATE_NAME="TRIAL"
# create the template
python3 -m templates.template-pubsub-bigquery \
--runner DataflowRunner \
--project $PROJECT \
--staging_location gs://$BUCKET/staging \
--temp_location gs://$BUCKET/temp \
--template_location gs://$BUCKET/templates/$TEMPLATE_NAME \
--streaming
创建管道(会产生您提到的错误,但仍会创建模板)。 还有
# Fill job-name and gcs location accordingly
# Uncomment and fill the parameters should you want to use your own
gcloud dataflow jobs run <job-name> \
--gcs-location "gs://<MYBUCKET>/dataflow/templates/mytemplate"
# --parameters input_topic="",output_table=""
运行管道。
正如我所说,模板已正确创建,管道正常运行。
修改
实际上,取消功能在模板中无法正常使用。它似乎是一个问题,它需要模板创建时的工作ID,而该ID当然不存在,因此它会忽略该功能。
我发现this other post可以处理管道上的Job ID。我尝试了一些调整,以使其在模板代码本身内工作,但我认为这不是必需的。如果您想安排它们的执行时间,我会选择一个更简单的选项,并在特定时间(例如,格林尼治标准时间9:01)执行流式传输管道模板,并使用脚本取消该管道
import logging,re,os
from googleapiclient.discovery import build
from oauth2client.client import GoogleCredentials
def retrieve_job_id():
#Fill as needed
project = '<project-id>'
job_prefix = "<job-name>"
location = '<location>'
logging.info("Looking for jobs with prefix {} in region {}...".format(job_prefix,location))
try:
credentials = GoogleCredentials.get_application_default()
dataflow = build('dataflow','v1b3',credentials=credentials)
result = dataflow.projects().locations().jobs().list(
projectId=project,location=location,).execute()
job_id = "none"
for job in result['jobs']:
if re.findall(r'' + re.escape(job_prefix) + '',job['name']):
job_id = job['id']
break
logging.info("Job ID: {}".format(job_id))
return job_id
except Exception as e:
logging.info("Error retrieving Job ID")
raise KeyError(e)
os.system('gcloud dataflow jobs cancel {}'.format(retrieve_job_id()))
在另一时间(例如,格林尼治标准时间9:05)。该脚本假定您每次都使用相同的作业名称运行该脚本,并采用该名称的最新外观并将其取消。我尝试了几次,效果很好。
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