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aws-google-auth

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This command-line tool allows you to acquire AWS temporary (STS) credentials using Google Apps as a federated (Single Sign-On, or SSO) provider.

Setup

You'll first have to set up Google Apps as a SAML identity provider (IdP) for AWS. There are tasks to be performed on both the Google Apps and the Amazon sides; these references should help you with those configurations:

If you need a fairly simple way to assign users to roles in AWS accounts, we have another tool called Google AWS Federator that might help you.

Important Data

You will need to know Google's assigned Identity Provider ID, and the ID that they assign to the SAML service provider.

Once you've set up the SAML SSO relationship between Google and AWS, you can find the SP ID by drilling into the Google Apps console, under Apps > SAML Apps > Settings for AWS SSO -- the URL will include a component that looks like ...#AppDetails:service=123456789012... -- that number is GOOGLE_SP_ID

You can find the GOOGLE_IDP_ID, again from the admin console, via Security > Set up single sign-on (SSO) -- the SSO URL includes a string like https://accounts.google.com/o/saml2/idp?idpid=aBcD01AbC where the last bit (after the =) is the IDP ID.

Installation

You can install quite easily via pip, if you want to have it on your local system:

# For basic installation
localhost$ sudo pip install aws-google-auth

# For installation with U2F support
localhost$ sudo pip install aws-google-auth[u2f]

Note If using ZSH you will need to quote the install, as below:

localhost$ sudo pip install "aws-google-auth[u2f]"

If you don't want to have the tool installed on your local system, or if you prefer to isolate changes, there is a Dockerfile provided, which you can build with:

# Perform local build
localhost$ cd ..../aws-google-auth && docker build -t aws-google-auth .

# Use the Docker Hub version
localhost$ docker pull cevoaustralia/aws-google-auth

Development

If you want to develop the AWS-Google-Auth tool itself, we thank you! In order to help you get rolling, you'll want to install locally with pip. Of course, you can use your own regular workflow, with tools like virtualenv.

# Install (without U2F support)
pip install -e .

# Install (with U2F support)
pip install -e .[u2f]

We welcome you to review our code of conduct and contributing documents.

Usage

$ aws-google-auth -h
usage: aws-google-auth [-h] [-u USERNAME] [-I IDP_ID] [-S SP_ID] [-R REGION]
                       [-d DURATION] [-p PROFILE] [-D] [-q]
                       [--bg-response BG_RESPONSE]
                       [--saml-assertion SAML_ASSERTION] [--no-cache]
                       [--print-creds] [--resolve-aliases]
                       [--save-failure-html] [--save-saml-flow] [-a | -r ROLE_ARN] [-k]
                       [-l {debug,info,warn}] [-V]

Acquire temporary AWS credentials via Google SSO

optional arguments:
  -h, --help            show this help message and exit
  -u USERNAME, --username USERNAME
                        Google Apps username ($GOOGLE_USERNAME)
  -I IDP_ID, --idp-id IDP_ID
                        Google SSO IDP identifier ($GOOGLE_IDP_ID)
  -S SP_ID, --sp-id SP_ID
                        Google SSO SP identifier ($GOOGLE_SP_ID)
  -R REGION, --region REGION
                        AWS region endpoint ($AWS_DEFAULT_REGION)
  -d DURATION, --duration DURATION
                        Credential duration (defaults to value of $DURATION, then
                        falls back to 43200)
  -p PROFILE, --profile PROFILE
                        AWS profile (defaults to value of $AWS_PROFILE, then
                        falls back to 'sts')
  -D, --disable-u2f     Disable U2F functionality.
  -q, --quiet           Quiet output
  --bg-response BG_RESPONSE
                        Override default bgresponse challenge token ($GOOGLE_BG_RESPONSE).
  --saml-assertion SAML_ASSERTION
                        Base64 encoded SAML assertion to use.
  --no-cache            Do not cache the SAML Assertion.
  --print-creds         Print Credentials.
  --resolve-aliases     Resolve AWS account aliases.
  --save-failure-html   Write HTML failure responses to file for
                        troubleshooting.
  --save-saml-flow      Write all GET and PUT requests and HTML responses to/from Google to files for troubleshooting.
  -a, --ask-role        Set true to always pick the role
  -r ROLE_ARN, --role-arn ROLE_ARN
                        The ARN of the role to assume ($AWS_ROLE_ARN)
  -k, --keyring         Use keyring for storing the password.
  -l {debug,info,warn}, --log {debug,info,warn}
                        Select log level (default: warn)
  -V, --version         show program's version number and exit

Note If you want a longer session than the AWS default 3600 seconds (1 hour) duration, you must also modify the IAM Role to permit this. See the AWS documentation for more information.

Native Python

  1. Execute aws-google-auth
  2. You will be prompted to supply each parameter

Note You can skip prompts by either passing parameters to the command, or setting the specified Environment variables.

Via Docker

  1. Set environment variables for anything listed in Usage with ($VARIABLE) after command line option:

    GOOGLE_USERNAME, GOOGLE_IDP_ID, and GOOGLE_SP_ID (see above under "Important Data" for how to find the last two; the first one is usually your email address)

    AWS_PROFILE: Optional profile name you want the credentials set for (default is 'sts')

    ROLE_ARN: Optional ARN of the role to assume

  2. For Docker: docker run -it -e GOOGLE_USERNAME -e GOOGLE_IDP_ID -e GOOGLE_SP_ID -e AWS_PROFILE -e ROLE_ARN -v ~/.aws:/root/.aws cevoaustralia/aws-google-auth

You'll be prompted for your password. If you've set up an MFA token for your Google account, you'll also be prompted for the current token value.

If you have a U2F security key added to your Google account, you won't be able to use this via Docker; the Docker container will not be able to access any devices connected to the host ports. You will likely see the following error during runtime: "RuntimeWarning: U2F Device Not Found".

If you have more than one role available to you (and you haven't set up ROLE_ARN), you'll be prompted to choose the role from a list.

Feeding password from stdin

To enhance usability when using third party tools for managing passwords (aka password manager) you can feed data in aws-google-auth from stdin.

When receiving data from stdin aws-google-auth disables the interactive prompt and uses stdin data.

Before #82, all interactive prompts could be fed from stdin already apart from the Google Password: prompt.

Example usage: ` $ password-manager show password | aws-google-auth Google Password: MFA token: Assuming arn:aws:iam::123456789012:role/admin Credentials Expiration: ... `

Note: this feature is intended for password manager integration, not for passing passwords from command line. Please use interactive prompt if you need to pass the password manually, as this provide enhanced security avoid password leakage to shell history.

Storage of profile credentials

Through the use of AWS profiles, using the -p or --profile flag, the aws-google-auth utility will store the supplied username, IDP and SP details in your ./aws/config files.

When re-authenticating using the same profile, the values will be remembered to speed up the re-authentication process. This enables an approach that enables you to enter your username, IPD and SP values once and then after only need to re-enter your password (and MFA if enabled).

Creating an alias as below can be a quick and easy way to re-authenticate with a simple command shortcut.

` alias aws-development='unset AWS_PROFILE; aws-google-auth -I $GOOGLE_IDP_ID -S $GOOGLE_SP_ID -u $USERNAME -p aws-dev ; export AWS_PROFILE=aws-dev' `

Or, if you've alredy established a profile with valid cached values:

` alias aws-development='unset AWS_PROFILE; aws-google-auth -p aws-dev ; export AWS_PROFILE=aws-dev' `

Notes on Authentication

Google supports a number of 2-factor authentication schemes. Each of these results in a slightly different "next" URL, if they're enabled, during do_login

Google controls the preference ordering of these schemes in the case that you have multiple ones defined.

The varying 2-factor schemes and their representative URL fragments handled by this tool are:

Method URL Fragment
No second factor (none)
TOTP (eg Google
Authenticator or Authy)
 .../signin/challenge/totp/...
SMS (or voice
call)
 .../signin/challenge/ipp/...
SMS (or voice
call) with number submission
 .../signin/challenge/iap/...
Google Prompt
(phone app)
 .../signin/challenge/az/...
Security key
(eg yubikey)
 .../signin/challenge/sk/...
Dual prompt
(Validate 2FA )
 .../signin/challenge/dp/...
Backup code
(printed codes)
 ... (unknown yet) ...

Acknowledgments

This work is inspired by keyme -- their digging into the guts of how Google SAML auth works is what's enabled it.

The attribute management and credential injection into AWS configuration files was heavily borrowed from aws-adfs <https://github.com/venth/aws-adfs>