town/cmd/welcome

welcome command

this command is used to exchange a town invite token for a user account. it is responsible for:

1. accepting and validating an invite token generated by the review command
2. accepting and validating a new user's username choice (ie enforcing rules and checking for dupes)
3. accepting and validating a user's email for use in account recovery (defaulting to an email embedded in the invite token)
4. accepting and validating a display name
5. asking what shell they'd like
6. accepting and validating a user's public ssh key

upon receipt of these things a user account is created. if it fails, the user is told about the failure and told to email root@tilde.town for guidance; us admins get a local mail about the problem.

upon successful creation, welcome prints a message on STDOUT suggesting how to log in then quits.

It is risky to let welcome create users but no riskier at a high level than the Django admin we had. I can re-use the sudoers trick I did there for the welcome user.

an invite token

an invite token consists of two pieces that are then base64 encoded. the first piece is a random string of 30 characters (alphanumeric and symbols except space) and the second is an email address the invite was sent to; they are separated by a space.

sudoers config

something like:

welcome ALL=(ALL)NOPASSWD:/usr/sbin/adduser,/usr/sbin/usermod,/bin/mkdir,/town/bin/generate_welcome_present.sh

though I will likely move welcome_present generation inline to welcome itself.

user creation flow

once we accept what we need from the user accepting an invite, the flow looks like:

1. create user account a. run adduser, set shell and displayname b. add user to town group
2. write authorized keys a. create ~/.ssh b. write ~/.ssh/authorized_keys2 and put their key in there c. write blank ~/.ssh/authorized_keys with note about adding custom keys
3. generate welcome gift
4. alert hooks (more of a future idea; but it would be nice to have a "WELCOME NEW USER!" in the mailing list / IRC / etc)