Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to use waiter functionality for bucket_not_exists using Boto3 and AWS Client?
Problem Statement − Use boto3 library in Python to check whether a bucket does not exist using waiter functionality. For example, use waiters to check whether Bucket_2 does not exist in S3.
Approach/Algorithm to solve this problem
Step 1 − Import boto3 and botocore exceptions to handle exceptions.
Step 2 − Use bucket_name as the parameter in the function.
Step 3 − Create an AWS session using boto3 library.
Step 4 − Create an AWS client for S3.
Step 5 − Now create the wait object for bucket_not_exists using get_waiter function.
Step 6 − Now, use the wait object to validate whether the bucket does not exist. By default, it checks in every 5 seconds until a successful state is reached. Here successful state means bucket should not be present in S3. An error is returned after 20 failed checks. However, the user can define polling time and max attempts.
Step 7 − It returns None.
Step 8 − Handle the generic exception if something went wrong while checking the bucket.
Example
Use the following code to use waiter to check whether bucket_not_exists −
import boto3
from botocore.exceptions import ClientError
def use_waiters_check_bucket_not_exists(bucket_name):
session = boto3.session.Session()
s3_client = session.client('s3')
try:
waiter = s3_client.get_waiter('bucket_not_exists')
waiter.wait(Bucket=bucket_name,
WaiterConfig={
'Delay': 2, 'MaxAttempts': 5})
print('Bucket not exist: ' + bucket_name)
except ClientError as e:
raise Exception( "boto3 client error in use_waiters_check_bucket_not_exists: " + e.__str__())
except Exception as e:
raise Exception( "Unexpected error in use_waiters_check_bucket_not_exists: " + e.__str__())
print(use_waiters_check_bucket_not_exists("Bucket_2"))
print(use_waiters_check_bucket_not_exists("Bucket_1"))Output
Bucket not exist: Bucket_2 None botocore.exceptions.WaiterError: Waiter BucketNotExists failed: Max attempts exceeded "Unexpected error in use_waiters_check_bucket_not_exists: " + e.__str__()) Exception: Unexpected error in use_waiters_check_bucket_not_exists: Waiter BucketNotExists failed: Max attempts exceed
For Bucket_2, the output is print statement and None. Since the response doesn’t return anything, it prints None.
For Bucket_1, the output is an exception, since this bucket exists even after max attempts to check.
In exception, it can be read that Max attempts exceeded.
732 Views
