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AWS CLI Configuration Variables

Configuration values for the AWS CLI can come from several sources:

  • As a command line option
  • As an environment variable
  • As a value in the AWS CLI config file
  • As a value in the AWS Shared Credential file

Some options are only available in the AWS CLI config. This topic guide covers all the configuration variables available in the AWS CLI.

Note that if you are just looking to get the minimum required configuration to run the AWS CLI, we recommend running aws configure, which will prompt you for the necessary configuration values.

Config File Format

The AWS CLI config file, which defaults to ~/.aws/config has the following format:

[default]
aws_access_key_id=foo
aws_secret_access_key=bar
region=us-west-2

The default section refers to the configuration values for the default profile. You can create profiles, which represent logical groups of configuration. Profiles that aren't the default profile are specified by creating a section titled "profile profilename":

[profile testing]
aws_access_key_id=foo
aws_secret_access_key=bar
region=us-west-2

Nested Values

Some service specific configuration, discussed in more detail below, has a single top level key, with nested sub values. These sub values are denoted by indentation:

[profile testing]
aws_access_key_id = foo
aws_secret_access_key = bar
region = us-west-2
s3 =
  max_concurrent_requests=10
  max_queue_size=1000

General Options

The AWS CLI has a few general options:

Variable Option Config Entry Environment Variable Description
profile --profile N/A AWS_PROFILE Default profile name
region --region region AWS_DEFAULT_REGION Default AWS Region
output --output output AWS_DEFAULT_OUTPUT Default output style
cli_timestamp_format N/A cli_timestamp_format N/A Output format of timestamps
cli_follow_urlparam N/A cli_follow_urlparam N/A Fetch URL url parameters
ca_bundle --ca-bundle ca_bundle AWS_CA_BUNDLE CA Certificate Bundle
parameter_validation   parameter_validation   Toggles parameter validation

The third column, Config Entry, is the value you would specify in the AWS CLI config file. By default, this location is ~/.aws/config. If you need to change this value, you can set the AWS_CONFIG_FILE environment variable to change this location.

The valid values of the output configuration variable are:

  • json
  • table
  • text

cli_timestamp_format controls the format of timestamps displayed by the AWS CLI. The valid values of the cli_timestamp_format configuration variable are:

  • none - Display the timestamp exactly as received from the HTTP response.
  • iso8601 - Reformat timestamp using iso8601 in the UTC timezone.

cli_follow_urlparam controls whether or not the CLI will attempt to follow URL links in parameters that start with either prefix https:// or http://. The valid values of the cli_follow_urlparam configuration variable are:

  • true - This is the default value. With this configured the CLI will follow any string parameters that start with https:// or http:// will be fetched, and the downloaded content will be used as the parameter instead.
  • false - The CLI will not treat strings prefixed with https:// or http:// any differently than normal string parameters.

parameter_validation controls whether parameter validation should occur when serializing requests. The default is True. You can disable parameter validation for performance reasons. Otherwise, it's recommended to leave parameter validation enabled.

When you specify a profile, either using --profile profile-name or by setting a value for the AWS_PROFILE environment variable, profile name you provide is used to find the corresponding section in the AWS CLI config file. For example, specifying --profile development will instruct the AWS CLI to look for a section in the AWS CLI config file of [profile development].

Precedence

The above configuration values have the following precedence:

  • Command line options
  • Environment variables
  • Configuration file

Credentials

Credentials can be specified in several ways:

  • Environment variables
  • The AWS Shared Credential File
  • The AWS CLI config file
Variable Creds/Config Entry Environment Variable Description
access_key aws_access_key_id AWS_ACCESS_KEY_ID AWS Access Key
secret_key aws_secret_access_key AWS_SECRET_ACCESS_KEY AWS Secret Key
token aws_session_token AWS_SESSION_TOKEN AWS Token (temp credentials)
metadata_service_timeout metadata_service_timeout AWS_METADATA_SERVICE_TIMEOUT EC2 metadata creds timeout
metadata_service_num_attempts metadata_service_num_attempts AWS_METADATA_SERVICE_NUM_ATTEMPTS EC2 metadata creds retry count

The second column specifies the name that you can specify in either the AWS CLI config file or the AWS Shared credentials file (~/.aws/credentials).

The Shared Credentials File

The shared credentials file has a default location of ~/.aws/credentials. You can change the location of the shared credentials file by setting the AWS_SHARED_CREDENTIALS_FILE environment variable.

This file is an INI formatted file with section names corresponding to profiles. With each section, the three configuration variables shown above can be specified: aws_access_key_id, aws_secret_access_key, aws_session_token. These are the only supported values in the shared credential file. Also note that the section names are different than the AWS CLI config file (~/.aws/config). In the AWS CLI config file, you create a new profile by creating a section of [profile profile-name], for example:

[profile development]
aws_access_key_id=foo
aws_secret_access_key=bar

In the shared credentials file, profiles are not prefixed with profile, for example:

[development]
aws_access_key_id=foo
aws_secret_access_key=bar

Precedence

Credentials from environment variables have precedence over credentials from the shared credentials and AWS CLI config file. Credentials specified in the shared credentials file have precedence over credentials in the AWS CLI config file. If AWS_PROFILE environment variable is set and the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables are set, then the credentials provided by AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY will override the credentials located in the profile provided by AWS_PROFILE.

Using AWS IAM Roles

If you are on an Amazon EC2 instance that was launched with an IAM role, the AWS CLI will automatically retrieve credentials for you. You do not need to configure any credentials.

Additionally, you can specify a role for the AWS CLI to assume, and the AWS CLI will automatically make the corresponding AssumeRole calls for you. Note that configuration variables for using IAM roles can only be in the AWS CLI config file.

You can specify the following configuration values for configuring an IAM role in the AWS CLI config file:

  • role_arn - The ARN of the role you want to assume.
  • source_profile - The AWS CLI profile that contains credentials / configuration the CLI should use for the initial assume-role call. This profile may be another profile configured to use assume-role, though if static credentials are present in the profile they will take precedence. This parameter cannot be provided alongside credential_source.
  • credential_source - The credential provider to use to get credentials for the initial assume-role call. This parameter cannot be provided alongside source_profile. Valid values are:
    • Environment to pull source credentials from environment variables.
    • Ec2InstanceMetadata to use the EC2 instance role as source credentials.
    • EcsContainer to use the ECS container credentials as the source credentials.
  • external_id - A unique identifier that is used by third parties to assume a role in their customers' accounts. This maps to the ExternalId parameter in the AssumeRole operation. This is an optional parameter.
  • mfa_serial - The identification number of the MFA device to use when assuming a role. This is an optional parameter. Specify this value if the trust policy of the role being assumed includes a condition that requires MFA authentication. The value is either the serial number for a hardware device (such as GAHT12345678) or an Amazon Resource Name (ARN) for a virtual device (such as arn:aws:iam::123456789012:mfa/user).
  • role_session_name - The name applied to this assume-role session. This value affects the assumed role user ARN (such as arn:aws:sts::123456789012:assumed-role/role_name/role_session_name). This maps to the RoleSessionName parameter in the AssumeRole operation. This is an optional parameter. If you do not provide this value, a session name will be automatically generated.

If you do not have MFA authentication required, then you only need to specify a role_arn and either a source_profile or a credential_source.

When you specify a profile that has IAM role configuration, the AWS CLI will make an AssumeRole call to retrieve temporary credentials. These credentials are then stored (in ~/.aws/cli/cache). Subsequent AWS CLI commands will use the cached temporary credentials until they expire, in which case the AWS CLI will automatically refresh credentials.

If you specify an mfa_serial, then the first time an AssumeRole call is made, you will be prompted to enter the MFA code. Subsequent commands will use the cached temporary credentials. However, when the temporary credentials expire, you will be re-prompted for another MFA code.

Example configuration using source_profile:

# In ~/.aws/credentials:
[development]
aws_access_key_id=foo
aws_secret_access_key=bar

# In ~/.aws/config
[profile crossaccount]
role_arn=arn:aws:iam:...
source_profile=development

Example configuration using credential_source to use the instance role as the source credentials for the assume role call:

# In ~/.aws/config
[profile crossaccount]
role_arn=arn:aws:iam:...
credential_source=Ec2InstanceMetadata

Sourcing Credentials From External Processes

Warning

The following describes a method of sourcing credentials from an external process. This can potentially be dangerous, so proceed with caution. Other credential providers should be preferred if at all possible. If using this option, you should make sure that the config file is as locked down as possible using security best practices for your operating system.

If you have a method of sourcing credentials that isn't built in to the AWS CLI, you can integrate it by using credential_process in the config file. The AWS CLI will call that command exactly as given and then read json data from stdout. The process must write credentials to stdout in the following format:

{
  "Version": 1,
  "AccessKeyId": "",
  "SecretAccessKey": "",
  "SessionToken": "",
  "Expiration": ""
}

The Version key must be set to 1. This value may be bumped over time as the payload structure evolves.

The Expiration key is an ISO8601 formatted timestamp. If the Expiration key is not returned in stdout, the credentials are long term credentials that do not refresh. Otherwise the credentials are considered refreshable credentials and will be refreshed automatically. NOTE: Unlike with assume role credentials, the AWS CLI will NOT cache process credentials. If caching is needed, it must be implemented in the external process.

The process can return a non-zero RC to indicate that an error occurred while retrieving credentials.

Some process providers may need additional information in order to retrieve the appropriate credentials. This can be done via command line arguments. NOTE: command line options may be visible to process running on the same machine.

Example configuration:

[profile dev]
credential_process = /opt/bin/awscreds-custom

Example configuration with parameters:

[profile dev]
credential_process = /opt/bin/awscreds-custom --username monty

Service Specific Configuration

API Versions

The API version to use for a service can be set using the api_versions key. To specify an API version, set the API version to the name of the service as a sub value for api_versions.

Example configuration:

[profile development]
aws_access_key_id=foo
aws_secret_access_key=bar
api_versions =
    ec2 = 2015-03-01
    cloudfront = 2015-09-17

By setting an API version for a service, it ensures that the interface for that service's commands is representative of the specified API version.

In the example configuration, the ec2 CLI commands will be representative of Amazon EC2's 2015-03-01 API version and the cloudfront CLI commands will be representative of Amazon CloudFront's 2015-09-17 API version.

Amazon S3

There are a number of configuration variables specific to the S3 commands. See AWS CLI S3 Configuration (aws help topics s3-config) for more details.

OS Specific Configuration

Locale

If you have data stored in AWS that uses a particular encoding, you should make sure that your systems are configured to accept that encoding. For instance, if you have unicode characters as part of a key on EC2 you will need to make sure that your locale is set to a unicode-compatible locale. How you configure your locale will depend on your operating system and your specific IT requirements. One option for UNIX systems is the LC_ALL environment variable. Setting LC_ALL=en_US.UTF-8, for instance, would give you a United States English locale which is compatible with unicode.