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How to use Boto3 to start a crawler in AWS Glue Data Catalog

In this article, we will see how a user can start a crawler in AWS Glue Data Catalog.

Example

Problem Statement: Use boto3 library in Python to start a crawler.

Approach/Algorithm to solve this problem

  • Step 1: Import boto3 and botocore exceptions to handle exceptions

  • Step 2: crawler_name is the parameter in this function.

  • Step 3: Create an AWS session using boto3 lib. Make sure region_name is mentioned in the default profile. If it is not mentioned, then explicitly pass the region_name while creating the session.

  • Step 4: Create an AWS client for glue.

  • Step 5: Now use the start_crawler function and pass the parameter crawler_name as Name.

  • Step 6: It returns the response metadata and starts the crawler irrespective of its schedule. If the status of crawler is running, then it throws CrawlerRunningException.

  • Step 7: Handle the generic exception if something went wrong while starting a crawler.

Example Code

The following code starts a crawler in AWS Glue Data Catalog −

import boto3
from botocore.exceptions import ClientError

def start_a_crawler(crawler_name)
   session = boto3.session.Session()
   glue_client = session.client('glue')
   try:
      response = glue_client.start_crawler(Name=crawler_name)
      return response
   except ClientError as e:
      raise Exception("boto3 client error in start_a_crawler: " + e.__str__())
   except Exception as e:
      raise Exception("Unexpected error in start_a_crawler: " + e.__str__())

#1st time start the crawler
print(start_a_crawler("Data Dimension"))
#2nd time run, before crawler completes the operation
print(start_a_crawler("Data Dimension"))

Output

#1st time start the crawler
{'ResponseMetadata': {'RequestId': '73e50130-*****************8e', 'HTTPStatusCode': 200, 'HTTPHeaders': {'date': 'Sun, 28 Mar 2021 07:26:55 GMT', 'content-type': 'application/x-amz-json-1.1', 'content-length': '2', 'connection': 'keep-alive', 'x-amzn-requestid': '73e50130-***************8e'}, 'RetryAttempts': 0}}

#2nd time run, before crawler completes the operation
Exception: boto3 client error in start_a_crawler: An error occurred (CrawlerRunningException) when calling the StartCrawler operation: Crawler with name Data Dimension has already started