AWS Assume daemon

This script automatically assumes every 15 minutes the specified role using a Yubikey as MFA (multi factor authentication) and updates ~/.aws/credentials.

As long as you've got your yubikey connected to your computer you'll never have to enter a second factor authentication code for the aws cli. As other tools / libraries (boto3) use ~/.aws/credentials as well you don't have to enter a token for these either.

Usage

You can install aws_assume using pip (pip install aws_assume), I recommend to install aws_assume using poetry (poetry install aws_assume) or in a virtualenv.

Your ~/.aws/credentials should contain your credentials and a profile with the the keys aws_access_key_id, aws_secret_access_key and aws_session_token.

For example:

~/.aws/credentials

[default]
aws_access_key_id = ...(your key id)...
aws_secret_access_key = ...(your access key)...

[profile]
aws_access_key_id = ...(placeholder, can be anything)...
aws_secret_access_key = ...(placeholder, can be anything)...
aws_session_token = ...(placeholder, can be anything)...

Your ~/.aws/credentials will be updated in place, only the specified profile section should be touched (your comments will be safe).

Older versions are rotated up to 5 items.

Next _assume should be started with the following arguments:

_assume --rolearn ... --oath_slot=... --serialnumber=... --profile_name=... --access-key-id=... --secret-access-key=... --mfa-session-duration=...

You should only run one _assume process per profile, I use systemd for starting _assume, by using the following unit file:

~/.config/systemd/user/aws_assume@.service

[Unit]
Description=Amazon Web Services token daemon

[Service]
Type=simple
ExecStart=%h/bin/_assume --rolearn='...%i...' --oath_slot=... --serialnumber=... --profile_name='...%i...' --access-key-id='...' --secret-access-key='...'
Restart=on-failure

[Install]
WantedBy=default.target

And reload systemd using systemctl --user daemon-reload, start _assume using systemctl --user start aws_assume@...

If you're not so fortunate to have systemd you can also use something like supervisord to start _assume.

~/supervisord.conf

[supervisord]

[supervisorctl]
serverurl=unix:///home/user/supervisord.sock

[unix_http_server]
file=/home/user/supervisord.sock

[rpcinterface:supervisor]
supervisor.rpcinterface_factory = supervisor.rpcinterface:make_main_rpcinterface

[program:assume-...]
command=/home/user/bin/_assume --rolearn=... --oath_slot=... --serialnumber=... --profile_name=... --access-key-id=... --secret-access-key=...
autorestart=true

Start supervisord using supervisord -c supervisor.conf and start assume using supervisorctl -c supervisor.conf start assume-....