Boto3 Documentation

Boto3 is the AWS SDK for Python used to create, configure, and manage AWS services like Amazon EC2 and Amazon S3. It provides two primary ways to interact with AWS:

1. Object-oriented API: A high-level interface for managing services.
2. Low-level access: Direct access to AWS service APIs.

Developers commonly refer to the SDK as "Boto3".

Boto3 emits a set of events that users can register to customize clients or resources and modify the behavior of method calls.

Event Naming Conventions: When registering handlers, you can use keywords in the event name to target specific scopes:

• service-name: The value used to instantiate a client (e.g., s3).
• operation-name: The underlying API operation name (e.g., ListObjectsV2). You can retrieve this via client.meta.method_to_api_mapping.
• resource-name: The name of the resource class (e.g., ServiceResource).

Conditional Events:

• creating-resource-class (Order 2): Emitted ONLY when using a service resource.
• after-call (Order 8): Emitted once the API response is received.
• after-call-error (Order 9): Emitted when an unsuccessful API response is received.

Boto3 provides several distinct interfaces and tools for interacting with AWS services:

• Resources: A high-level, object-oriented interface.
• Collections: Tools to iterate and manipulate groups of resources.
• Clients: Low-level service connections.
• Paginators: Automatic paging of responses to handle large result sets.
• Waiters: Mechanisms to block execution until a specific service state is reached.

Additionally, Boto3 manages sessions, credentials, configuration, authentication, parameter/response handling, an event system for customization, and retry logic.

Boto3 searches for configuration values in a specific order. It uses the first value it finds and stops searching. The lookup order is:

1. A Config object passed as the config parameter when creating a client.
2. Environment variables.
3. The ~/.aws/config file.

Note that configurations are not wholly atomic; a specific environment variable or a Config object can overwrite individual values found in the AWS config file.

Boto3 is built on top of Botocore, which is also used by the AWS CLI.

• Botocore provides the low-level clients, session management, and credential/configuration data.
• Boto3 extends Botocore by adding its own session management, high-level Resources, and Collections.

Session objects are not thread safe and should not be shared across threads or processes. To ensure thread safety, create a new Session object inside each thread or process.

import boto3
import boto3.session
import threading

class MyTask(threading.Thread):
    def run(self):
        # Here we create a new session per thread
        session = boto3.session.Session()

        # Next, we create a resource client using our thread's session object
        s3 = session.resource('s3')

        # Put your thread-safe code here

Certain configuration settings like api_versions and s3 are nested and require specific indentation when manually editing the ~/.aws/config file.

Example for api_versions:

[default]
region = us-east-1
api_versions =
    ec2 = 2015-03-01
    cloudfront = 2015-09-17

Example for s3 settings:

[default]
region = us-east-1
s3 =
    addressing_style = path
    signature_version = s3v4

To use IAM Identity Center (formerly AWS SSO), first configure your SSO profiles using the AWS CLI (v2). Once configured, you can use the profile in Boto3 by specifying the profile_name in a Session or setting the AWS_PROFILE environment variable.

import boto3

# Using a profile configured for IAM Identity Center
session = boto3.Session(profile_name='my-sso-profile')
s3_client = session.client('s3')

Use generate_presigned_url to grant temporary access to an S3 object to users without AWS credentials. It is recommended to configure the S3 client with Signature Version 4 (s3v4), the specific AWS region, and virtual-hosted style addressing (s3={'addressing_style': 'virtual'}).

To download the object, the recipient can use the returned URL in a browser or via an HTTP GET request.