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aws-saml-auth

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

Installation

The easiest option is to to install with pip

python3 -m pip install aws-saml-auth

Its also possible to use the docker image ekreative/aws-saml-auth.

Setup

You will need to know your SAML Providers SSO URL.

For Google Workspace the url by right clicking copy url from the AWS App that you setup in the Apps menu or from the 'Test SAML Login' button in the Apps settings.

You can store the url in an env var or pass it to the --login-url argument.

export ASA_LOGIN_URL="https://accounts.google.com/o/saml2/initsso?idpid=XXX&spid=XXX&forceauthn=false"

If you dont have an AWS SAML App available talk to your Administrator and point them to the Setup AWS SAML and Google Workspace section below.

Credential Process

In you aws config file (~/.aws/config) you can setup a profile to use the credential process

[profile my_profile]
credential_process = aws-saml-auth --credential-process
region = eu-west-1
asa.login_url = https://accounts.google.com/o/saml2/initsso?idpid=some_idp&spid=some_spid&forceauthn=false

If you have multiple roles available you must add the asa.role_arn setting. You can also use this to have multiple profiles with different AWS accounts.

AWS process will trigger the login flow automatically whenever your credentials expire.

Usage

You can run the command aws-saml-auth to authenticate aws-cli. By default it will edit your default credentials. You can export the variable AWS_PROFILE=my_profile and then aws-saml-auth and aws-cli will use this profile.

$ aws-saml-auth -h
usage: aws-saml-auth [-h] [--redirect-server | -L LOGIN_URL] [-R REGION] [-d DURATION | --auto-duration] [-p PROFILE] [-A ACCOUNT] [-q] [--saml-assertion SAML_ASSERTION] [--no-saml-cache] [--print-creds | --credential-process]
                 [--no-resolve-aliases] [--port PORT] [--no-ask-role | -r ROLE_ARN] [-l {debug,info,warn}] [-V]

Acquire temporary AWS credentials via SAML

optional arguments:
  -h, --help            show this help message and exit
  --redirect-server     Run the redirect server on port ($PORT)
  -L LOGIN_URL, --login-url LOGIN_URL
                        SAML Provider login url ($ASA_LOGIN_URL)
  -R REGION, --region REGION
                        AWS region endpoint ($AWS_DEFAULT_REGION)
  -d DURATION, --duration DURATION
                        Credential duration in seconds (defaults to value of $ASA_DURATION, then falls back to 43200)
  --auto-duration       Tries to use the longest allowed duration ($ASA_AUTO_DURATION=1)
  -p PROFILE, --profile PROFILE
                        AWS profile (defaults to value of $AWS_PROFILE, then falls back to 'default')
  -A ACCOUNT, --account ACCOUNT
                        Filter for specific AWS account ($ASA_AWS_ACCOUNT)
  -q, --quiet           Quiet output
  --saml-assertion SAML_ASSERTION
                        Base64 encoded SAML assertion to use
  --no-saml-cache       Do not cache the SAML Assertion ($ASA_NO_SAML_CACHE=1)
  --print-creds         Print Credentials
  --credential-process  Output suitable for aws cli credential_process ($ASA_CREDENTIAL_PROCESS=1)
  --no-resolve-aliases  Do not resolve AWS account aliases. ($ASA_NO_RESOLVE_ALIASES=1)
  --port PORT           Port for the redirect server ($PORT)
  --no-ask-role         Never ask to pick the role ($ASA_NO_ASK_ROLE=1)
  -r ROLE_ARN, --role-arn ROLE_ARN
                        The ARN of the role to assume ($ASA_ROLE_ARN)
  -l {debug,info,warn}, --log {debug,info,warn}
                        Select log level (default: warn)
  -V, --version         show program's version number and exit

Via Docker

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

    ASA_LOGIN_URL (see above under "Important Data" for how to find these)

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

    ASA_ROLE_ARN: Optional ARN of the role to assume

  2. For Docker: docker run -it -e ASA_LOGIN_URL -e AWS_PROFILE -e ASA_ROLE_ARN -p 4589:4589 -v ~/.aws:/root/.aws ekreative/aws-saml-auth

You will be be shown a URL to visit in your browser

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

Storage of profile credentials

Through the use of AWS profiles, using the -p or --profile flag, the aws-saml-auth utility will store the supplied Login Url 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 provide your Login URL value only once

Setup AWS SAML and Google Workspace

You'll first have to set up your SAML identity provider (IdP) for AWS. There are tasks to be performed on both the Google Workspace 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.

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.

To enable browser based login, you will need to host the redirect server somewhere with HTTPS enabled, you might use a serverless google cloud run deployment for example:

gcloud run deploy --image gcr.io/my-project/aws-saml-auth --args=--redirect-server --platform managed

Beware for google cloud run you must copy the docker image to your account:

docker pull ekreative/aws-saml-auth
docker tag ekreative/aws-saml-auth gcr.io/my-project/aws-saml-auth
docker push gcr.io/my-project/aws-saml-auth

Then change your SAML provider settings so the ACS URL points to the redirect server.

You will also need to change the Trust Relationship of your IAM Role to allow SAML:aud to be the host of your redirect server.

See the example, replacing "https://redirect-server.com/saml" with your own.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Federated": "arn:aws:iam::XXX:saml-provider/XXX"
      },
      "Action": "sts:AssumeRoleWithSAML",
      "Condition": {
        "StringEquals": {
          "SAML:aud": [
            "https://signin.aws.amazon.com/saml",
            "https://redirect-server.com/saml"
          ]
        }
      }
    }
  ]
}

Development

If you want to develop the Aws-saml-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
pip install -e .

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

Acknowledgments

This work is inspired by aws-google-auth -- this version has changed to use browser login flow only and avoid handling user passwords.