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Configuration

Overview

Boto3 looks at various configuration locations until it finds configuration values. Boto3 adheres to the following lookup order when searching through sources for configuration values:

  • A Config object that's created and passed as the config parameter when creating a client
  • Environment variables
  • The ~/.aws/config file

Note

Configurations are not wholly atomic. This means configuration values set in your AWS config file can be singularly overwritten by setting a specific environment variable or through the use of a Config object.

For details about credential configuration, see the Credentials guide.

Using the Config object

This option is for configuring client-specific configurations that affect the behavior of your specific client object only. As described earlier, there are options used here that will supersede those found in other configuration locations:

  • region_name (string) - The AWS Region used in instantiating the client. If used, this takes precedence over environment variable and configuration file values. But it doesn't overwrite a region_name value explicitly passed to individual service methods.
  • signature_version (string) - The signature version used when signing requests. Note that the default version is Signature Version 4. If you're using a presigned URL with an expiry of greater than 7 days, you should specify Signature Version 2.
  • s3 (related configurations; dictionary) - Amazon S3 service-specific configurations. For more information, see the Config reference.
  • retries (dictionary) - Client retry behavior configuration options that include retry mode and maximum retry attempts. For more information, see the Retries guide.

For more information about additional options, or for a complete list of options, see the Config reference.

To set these configuration options, create a Config object with the options you want, and then pass them into your client.

import boto3
from botocore.config import Config

my_config = Config(
    region_name = 'us-west-2',
    signature_version = 'v4',
    retries = {
        'max_attempts': 10,
        'mode': 'standard'
    }
)

client = boto3.client('kinesis', config=my_config)

Using environment variables

Configurations can be set through the use of system-wide environment variables. If set, these configurations are global and will affect all clients created unless explicitly overwritten through the use of a Config object.

AWS_ACCESS_KEY_ID
The access key for your AWS account.
AWS_SECRET_ACCESS_KEY
The secret key for your AWS account.
AWS_SESSION_TOKEN
The session key for your AWS account. This is only needed when you are using temporary credentials. The AWS_SECURITY_TOKEN environment variable can also be used, but is only supported for backward-compatibility purposes. AWS_SESSION_TOKEN is supported by multiple AWS SDKs in addition to Boto3.
AWS_DEFAULT_REGION
The default AWS Region to use, for example, us-west-1 or us-west-2.
AWS_PROFILE
The default profile to use, if any. If no value is specified, Boto3 attempts to search the shared credentials file and the config file for the default profile.
AWS_CONFIG_FILE
The location of the config file used by Boto3. By default this value is ~/.aws/config. You only need to set this variable if you want to change this location.
AWS_SHARED_CREDENTIALS_FILE
The location of the shared credentials file. By default this value is ~/.aws/credentials. You only need to set this variable if you want to change this location.
BOTO_CONFIG
The location of the Boto2 credentials file. This is not set by default. You only need to set this variable if you want to use credentials stored in Boto2 format in a location other than /etc/boto.cfg or ~/.boto.
AWS_CA_BUNDLE
The path to a custom certificate bundle to use when establishing SSL/TLS connections. Boto3 includes a CA bundle that it uses by default, but you can set this environment variable to use a different CA bundle.
AWS_METADATA_SERVICE_TIMEOUT
The number of seconds before a connection to the instance metadata service should time out. When attempting to retrieve credentials on an Amazon EC2 instance that is configured with an IAM role, a connection to the instance metadata service will time out after 1 second by default. If you know you're running on an EC2 instance with an IAM role configured, you can increase this value if needed.
AWS_METADATA_SERVICE_NUM_ATTEMPTS
When attempting to retrieve credentials on an Amazon EC2 instance that has been configured with an IAM role, Boto3 will make only one attempt to retrieve credentials from the instance metadata service before giving up. If you know your code will be running on an EC2 instance, you can increase this value to make Boto3 retry multiple times before giving up.
AWS_DATA_PATH
A list of additional directories to check when loading botocore data. You typically don't need to set this value. There are two built-in search paths: <botocoreroot>/data/ and ~/.aws/models. Setting this environment variable indicates additional directories to check first before falling back to the built-in search paths. Multiple entries should be separated with the os.pathsep character, which is : on Linux and ; on Windows.
AWS_STS_REGIONAL_ENDPOINTS
Sets AWS STS endpoint resolution logic. See the sts_regional_endpoints configuration file section for more information on how to use this.
AWS_MAX_ATTEMPTS
The total number of attempts made for a single request. For more information, see the max_attempts configuration file section.
AWS_RETRY_MODE
Specifies the types of retries the SDK will use. For more information, see the retry_mode configuration file section.

Using a configuration file

Boto3 will also search the ~/.aws/config file when looking for configuration values. You can change the location of this file by setting the AWS_CONFIG_FILE environment variable.

This file is an INI-formatted file that contains at least one section: [default]. You can create multiple profiles (logical groups of configuration) by creating sections named [profile profile-name]. If your profile name has spaces, you need to surround this value with quotation marks: [profile "my profile name"]. The following are all the config variables supported in the ~/.aws/config file.

api_versions

Specifies the API version to use for a particular AWS service.

The api_versions settings are nested configuration values that require special formatting in the AWS configuration file. If the values are set by the AWS CLI or programmatically by an SDK, the formatting is handled automatically. If you set them by manually editing the AWS configuration file, the following is the required format. Notice the indentation of each value.

[default]
region = us-east-1
api_versions =
    ec2 = 2015-03-01
    cloudfront = 2015-09-17
aws_access_key_id
The access key to use.
aws_secret_access_key
The secret access key to use.
aws_session_token
The session token to use. This is typically needed only when using temporary credentials. Note aws_security_token is supported for backward compatibility.
ca_bundle
The CA bundle to use. For more information, see the previous description of the AWS_CA_BUNDLE environment variable.
credential_process
Specifies an external command to run to generate or retrieve authentication credentials. For more information, see Sourcing credentials with an external process.
credential_source

To invoke an AWS service from an Amazon EC2 instance, you can use an IAM role attached to either an EC2 instance profile or an Amazon ECS container. In such a scenario, use the credential_source setting to specify where to find the credentials.

The credential_source and source_profile settings are mutually exclusive.

The following values are supported.

Ec2InstanceMetadata
Use the IAM role attached to the Amazon EC2 instance profile.
EcsContainer
Use the IAM role attached to the Amazon ECS container.
Environment
Retrieve the credentials from environment variables.
duration_seconds
The length of time in seconds of the role session. The value can range from 900 seconds (15 minutes) to the maximum session duration setting for the role. The default value is 3600 seconds (one hour).
external_id
Unique identifier to pass when making AssumeRole calls.
metadata_service_timeout
The number of seconds before timing out when retrieving data from the instance metadata service. For more information, see the previous documentation on AWS_METADATA_SERVICE_TIMEOUT.
metadata_service_num_attempts
The number of attempts to make before giving up when retrieving data from the instance metadata service. For more information, see the previous documentation on AWS_METADATA_SERVICE_NUM_ATTEMPTS.
mfa_serial
Serial number of the Amazon Resource Name (ARN) of a multi-factor authentication (MFA) device to use when assuming a role.
parameter_validation
Disable parameter validation (default is true, parameters are validated). This is a Boolean value that is either true or false. Whenever you make an API call using a client, the parameters you provide are run through a set of validation checks, including (but not limited to) required parameters provided, type checking, no unknown parameters, minimum length checks, and so on. Typically, you should leave parameter validation enabled.
region
The default AWS Region to use, for example, us-west-1 or us-west-2. When specifying a Region inline during client initialization, this property is named region_name.
role_arn
The ARN of the role you want to assume.
role_session_name
The role name to use when assuming a role. If this value is not provided, a session name will be automatically generated.
web_identity_token_file
The path to a file that contains an OAuth 2.0 access token or OpenID Connect ID token that is provided by the identity provider. The contents of this file will be loaded and passed as the WebIdentityToken argument to the AssumeRoleWithWebIdentity operation.
s3

Set Amazon S3-specific configuration data. Typically, these values do not need to be set.

The s3 settings are nested configuration values that require special formatting in the AWS configuration file. If the values are set by the AWS CLI or programmatically by an SDK, the formatting is handled automatically. If you set them manually by editing the AWS configuration file, the following is the required format. Notice the indentation of each value.

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

  • addressing_style: The S3 addressing style. When necessary, Boto automatically switches the addressing style to an appropriate value. The following values are supported.

    auto

    (Default) Attempts to use virtual, but falls back to path if necessary.

    path

    Bucket name is included in the URI path.

    virtual

    Bucket name is included in the hostname.

  • payload_signing_enabled: Specifies whether to include an SHA-256 checksum with Amazon Signature Version 4 payloads. Valid settings are true or false.

    For streaming uploads (UploadPart and PutObject) that use HTTPS and include a content-md5 header, this setting is disabled by default.

  • signature_version: The AWS signature version to use when signing requests. When necessary, Boto automatically switches the signature version to an appropriate value. The following values are recognized.

    s3v4

    (Default) Signature Version 4

    s3

    (Deprecated) Signature Version 2

  • use_accelerate_endpoint: Specifies whether to use the Amazon S3 Accelerate endpoint. The bucket must be enabled to use S3 Accelerate. Valid settings are true or false. Default: false

    Either use_accelerate_endpoint or use_dualstack_endpoint can be enabled, but not both.

  • use_dualstack_endpoint: Specifies whether to direct all Amazon S3 requests to the dual IPv4/IPv6 endpoint for the configured Region. Valid settings are true or false. Default: false

    Either use_accelerate_endpoint or use_dualstack_endpoint can be enabled, but not both.

source_profile

The profile name that contains credentials to use for the initial AssumeRole call.

The credential_source and source_profile settings are mutually exclusive.

sts_regional_endpoints

Sets AWS STS endpoint resolution logic. This configuration can also be set using the environment variable AWS_STS_REGIONAL_ENDPOINTS. By default, this configuration option is set to legacy. Valid values are the following:

  • regional

    Uses the STS endpoint that corresponds to the configured Region. For example, if the client is configured to use us-west-2, all calls to STS will be made to the sts.us-west-2.amazonaws.com regional endpoint instead of the global sts.amazonaws.com endpoint.

  • legacy

    Uses the global STS endpoint, sts.amazonaws.com, for the following configured Regions:

    • ap-northeast-1
    • ap-south-1
    • ap-southeast-1
    • ap-southeast-2
    • aws-global
    • ca-central-1
    • eu-central-1
    • eu-north-1
    • eu-west-1
    • eu-west-2
    • eu-west-3
    • sa-east-1
    • us-east-1
    • us-east-2
    • us-west-1
    • us-west-2

    All other Regions will use their respective regional endpoint.

tcp_keepalive
Toggles the TCP Keep-Alive socket option used when creating connections. By default this value is false; TCP Keepalive will not be used when creating connections. To enable TCP Keepalive with the system default configurations, set this value to true.
max_attempts
An integer representing the maximum number of attempts that will be made for a single request, including the initial attempt. For example, setting this value to 5 will result in a request being retried up to 4 times. If not provided, the number of retries will default to whatever is modeled, which is typically 5 total attempts in the legacy retry mode, and 3 in the standard and adaptive retry modes.
retry_mode

A string representing the type of retries Boto3 will perform. Valid values are the following:

  • legacy - The preexisting retry behavior. This is the default value if no retry mode is provided.
  • standard - A standardized set of retry rules across the AWS SDKs. This includes a standard set of errors that are retried and support for retry quotas, which limit the number of unsuccessful retries an SDK can make. This mode will default the maximum number of attempts to 3 unless a max_attempts is explicitly provided.
  • adaptive - An experimental retry mode that includes all the functionality of standard mode with automatic client-side throttling. This is a provisional mode whose behavior might change.
Developer guide
Credentials

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