Boto3 credentials can be configured in multiple ways. Regardless of the source or sources that you choose, you must have both AWS credentials and an AWS Region set in order to make requests.
If you have the AWS CLI, then you can use its interactive configure command to set up your credentials and default region:
aws configure
Follow the prompts and it will generate configuration files in the correct locations for you.
There are two types of configuration data in Boto3: credentials and non-credentials. Credentials include items such as aws_access_key_id, aws_secret_access_key, and aws_session_token. Non-credential configuration includes items such as which region to use or which addressing style to use for Amazon S3. For more information on how to configure non-credential configurations, see the Configuration guide.
Boto3 will look in several locations when searching for credentials. The mechanism in which Boto3 looks for credentials is to search through a list of possible locations and stop as soon as it finds credentials. The order in which Boto3 searches for credentials is:
Each of those locations is discussed in more detail below.
There are valid use cases for providing credentials to the client() method and Session object, these include:
The first option for providing credentials to Boto3 is passing them as parameters when creating clients:
import boto3
client = boto3.client(
's3',
aws_access_key_id=ACCESS_KEY,
aws_secret_access_key=SECRET_KEY,
aws_session_token=SESSION_TOKEN
)
The second option for providing credentials to Boto3 is passing them as parameters when creating a Session object:
import boto3
session = boto3.Session(
aws_access_key_id=ACCESS_KEY,
aws_secret_access_key=SECRET_KEY,
aws_session_token=SESSION_TOKEN
)
Warning
ACCESS_KEY, SECRET_KEY, and SESSION_TOKEN are variables that contain your access key, secret key, and optional session token. Note that the examples above do not have hard coded credentials. We do not recommend hard coding credentials in your source code.
Boto3 will check these environment variables for credentials:
Boto3 can also load credentials from ~/.aws/config. You can change this default location by setting the AWS_CONFIG_FILE environment variable. The config file is an INI format, with the same keys supported by the shared credentials file. The only difference is that profile sections must have the format of [profile profile-name], except for the default profile:
[default]
aws_access_key_id=foo
aws_secret_access_key=bar
[profile dev]
aws_access_key_id=foo2
aws_secret_access_key=bar2
[profile prod]
aws_access_key_id=foo3
aws_secret_access_key=bar3
The reason that section names must start with profile in the ~/.aws/config file is because there are other sections in this file that are permitted that aren't profile configurations.
Note
This is a different set of credentials configuration than using IAM roles for EC2 instances, which is discussed in a section below.
Within the ~/.aws/config file, you can also configure a profile to indicate that Boto3 should assume a role. When you do this, Boto3 will automatically make the corresponding AssumeRole calls to AWS STS on your behalf. It will handle in-memory caching as well as refreshing credentials as needed.
You can specify the following configuration values for configuring an IAM role in Boto3. For more information about a particular setting, see the Configuration section.
If MFA authentication is not enabled then you only need to specify a role_arn and a source_profile.
When you specify a profile that has an IAM role configuration, Boto3 will make an AssumeRole call to retrieve temporary credentials. Subsequent Boto3 API calls will use the cached temporary credentials until they expire, in which case Boto3 will then automatically refresh the credentials.
Please note that Boto3 does not write these temporary credentials to disk. This means that temporary credentials from the AssumeRole calls are only cached in-memory within a single session. All clients created from that session will share the same temporary credentials.
If you specify mfa_serial, then the first time an AssumeRole call is made, you will be prompted to enter the MFA code. Program execution will block until you enter the MFA code. You'll need to keep this in mind if you have an mfa_serial device configured, but would like to use Boto3 in an automated script.
Below is an example configuration for the minimal amount of configuration needed to configure an assume role profile:
# In ~/.aws/credentials:
[development]
aws_access_key_id=foo
aws_access_key_id=bar
# In ~/.aws/config
[profile crossaccount]
role_arn=arn:aws:iam:...
source_profile=development
See Using IAM Roles for general information on IAM roles.
Within the ~/.aws/config file, you can also configure a profile to indicate that Boto3 should assume a role. When you do this, Boto3 will automatically make the corresponding AssumeRoleWithWebIdentity calls to AWS STS on your behalf. It will handle in-memory caching as well as refreshing credentials, as needed.
You can specify the following configuration values for configuring an IAM role in Boto3:
Below is an example configuration for the minimal amount of configuration needed to configure an assume role with web identity profile:
# In ~/.aws/config
[profile web-identity]
role_arn=arn:aws:iam:...
web_identity_token_file=/path/to/a/token
This provider can also be configured via environment variables:
Note
These environment variables currently only apply to the assume role with web identity provider and do not apply to the general assume role provider configuration.
Boto3 will attempt to load credentials from the Boto2 config file. It first checks the file pointed to by BOTO_CONFIG if set, otherwise it will check /etc/boto.cfg and ~/.boto. Note that only the [Credentials] section of the boto config file is used. All other configuration data in the boto config file is ignored.
# Example ~/.boto file
[Credentials]
aws_access_key_id = foo
aws_secret_access_key = bar
Note
This credential provider is primarily for backwards compatibility purposes with Boto2.
If you are running on Amazon EC2 and no credentials have been found by any of the providers above, Boto3 will try to load credentials from the instance metadata service. In order to take advantage of this feature, you must have specified an IAM role to use when you launched your EC2 instance.
For more information on how to configure IAM roles on EC2 instances, see the IAM Roles for Amazon EC2 guide.
Note that if you've launched an EC2 instance with an IAM role configured, there's no explicit configuration you need to set in Boto3 to use these credentials. Boto3 will automatically use IAM role credentials if it does not find credentials in any of the other places listed previously.
If you're running on an EC2 instance, use AWS IAM roles. See the IAM Roles for Amazon EC2 guide for more information on how to set this up.
If you want to interoperate with multiple AWS SDKs (e.g Java, Javascript, Ruby, PHP, .NET, AWS CLI, Go, C++), use the shared credentials file (~/.aws/credentials). By using the shared credentials file, you can use a single file for credentials that will work in all AWS SDKs.