aws-runas 0.2.0

Execute a command using an AWS assumed role

A command to provide a friendly way to do an AWS STS AssumeRole operation so you can perform AWS API actions using a particular set of permissions. Includes integration with roles requiring MFA authentication! Works off of profile names configured in the AWS SDK configuration file.

This tool initially performs an AWS STS GetSessionToken call to handle MFA credentials, and caches the session credentials, then makes the AssumeRole call. This allows us to not have to re-enter the MFA information (if required) every time AssumeRole is called (or when the AssumeRole credentials expire), only when new Session Tokens are requested (by default 12 hours). Unlike older versions of this program, the cached credentials are not compatible with awscli, but you should be able to use aws-runas to wrap awscli commands using an assumed role without needing to input MFA info every time.

See the following for more information on AWS SDK configuration files:

• http://docs.aws.amazon.com/cli/latest/userguide/cli-config-files.html

• https://boto3.readthedocs.io/en/latest/guide/quickstart.html#configuration

• https://boto3.readthedocs.io/en/latest/guide/configuration.html#aws-config-file

Requirements

• Tested on python 2.7 and python 3

• boto3 python library, version 1.3.1 or higher

Installation

Using pip is the preferred method to install this tool, and will install the package from pypi. pip install aws-runas

It can also be installed via pip from a local copy of the source repo, pip install . from the repo directory should do the trick. Running make install should also work as well.

Configuration

To configure a profile in the .aws/config file for using AssumeRole, make sure the source_profile and role_arn attributes are set for the profile. The role_arn attribute will determine which role will be assumed for that profile. The source_profile attribute specifies the name of the profile which will be used to perform the GetSessionToken operation.

If the mfa_serial attribute is present in the profile configuration, That MFA device will be used when requesting or refreshing the session token.

Example:

[profile admin]

source_profile = default

role_arn = arn:aws:iam::987654321098:role/admin_role

mfa_serial = arn:aws:iam::123456789098:mfa/iam_user

Usage

usage: aws-runas [-h] [-l] [-m] [-e] [-s] [-r] [-v] [-V] [profile] …

Create an environment for interacting with the AWS API using an assumed role

positional arguments:

profile name of profile

cmd command to execute using configured profile

optional arguments:

-h, –help show this help message and exit

-l, –list-roles list role ARNs you are able to assume

-m, –list-mfa list the ARN of the MFA device associated with the account

-e, –expiration Show token expiration time

-s, –session print eval()-able session token info

-r, –refresh force a refresh of the cached credentials

-v, –verbose print verbose/debug messages

-V, –version print program version and exit

Listing available roles

Use the -l option to see the list of role ARNs your IAM account is authorized to assume. May be helpful for setting up your AWS config file. If profile arg is specified, list roles available for the given profile, or the default profile if not specified. May be useful if you have multiple profiles configured each with their own IAM role configurations

Listing available MFA devices

Use the -m option to list the ARNs of any MFA devices associated with your IAM account. May be helpful for setting up your AWS config file. If profile arg is specified, list MFA devices available for the given profile, or the default profile if not specified. May be useful if you have multiple profiles configured each with their own MFA device

Displaying session token expiration

Use the -e option to display the date and time which the session token will expire. If profile arg is specified, display info for the given profile, otherwise use the ‘default’ profile. Specifying the profile name may be useful if you have multiple profiles configured which you get session tokens for.

Injecting SessionToken credentials into the environment

Use the -s option to output and eval()-able set of environment variables for the session token credentials. If profile arg is specified, display the session token credentials for the given profile, otherwise use the default profile.

Example:

$ aws-runas -s

export AWS_ACCESS_KEY_ID=’xxxxxx’

export AWS_SECRET_ACCESS_KEY=’yyyyyy’

export AWS_SESSION_TOKEN=’zzzzz’

Or simply eval $(aws-runas -s) to add these env vars to the running environment. Since session tokens generally live for multiple hours, injecting these credentials into the environment may be useful when using tools which can do AssumeRole on their own, and manage/refresh the relativly short-lived AssumeRole credentials internally.

Injecting AssumeRole credentials into the environment

Running the program with only a profile name will output an eval()-able set of environment variables for the assumed role credentials which can be added to the current session.

Example:

$ aws-runas admin-profile

export AWS_ACCESS_KEY_ID=’xxxxxx’

export AWS_SECRET_ACCESS_KEY=’yyyyyy’

export AWS_SESSION_TOKEN=’zzzzz’

Or simply eval $(aws-runas admin-profile) to add these env vars in the current session. With the addition of caching session token credentials, and the ability to automatically refresh the credentials, eval-ing this output for assumed role credentials is no longer necessary for most cases, but will be left as a feature of this tool for the foreseeable future.

Running command using a profile

Running the program specifying a profile name and command will execute the command using the profile credentials, automatically performing any configured assumeRole operation, or MFA token gathering.

Example (run the command aws s3 ls using the profile admin-profile):

$ aws-runas admin-profile aws s3 ls

… <s3 bucket listing here> …

Running command using the default profile

Running the program using the default profile is no different than using a custom profile, simply use default as the profile name.

Contributing

The usual github model for forking the repo and creating a pull request is the preferred way to contribute to this tool. Bug fixes, enhancements, doc updates, translations are always welcomed.

Building from source

A Makefile has been included in the repository to handle the steps of creating the package and uploading it to pypi. If you don’t have the make utility installed, the contents of the Makefile should be instructive (and simple) enough to execute manually.

The following targets are available in the Makefile:

• package - the default target, calls the setup.py script to create the package to upload to pypi.

• upload - depends on the package target, and uploads the generated package archive to pypi.

• install - use pip to install the package locally

• clean - clean up the artifacts left by the package step.

• distclean - depends on the clean target, and additionally cleans up misc. files.