ws.nginxdbauth 1.1.1

Authenticate an nginx request against an SQL database

This packages answers an nginx auth subrequest by looking up the user/password in a database (mysql, postgresql, whatever sqlalchemy supports).

Usage

Configure database access

You’ll need to provide the DSN and the query using a configuration file:

[default]
dsn = postgresql://localhost/myusers
query = SELECT password FROM users WHERE username = :username AND role = :x_required_role
password_hash = bcrypt

See the sqlalchemy documentation for supported DSNs. Note that you have to install the respective driver python package (mysql-python, psycopg2, etc.) yourself.

Settings beginning with sqlalchemy. are stripped of that prefix and passed through to sqlalchemy.create_engine().

The query gets passed as SQL parameters the basic auth username and password as well as any request headers (lowercase, and - replaced with _). (If that is not flexible enough for your usecase, you’ll have to run separate instances with specialized queries, for the time being).

The query must return the hashed password of the user. Since for simple cases you might get away with using the SQL functions provided by your database to hash the password (e.g. mysql WHERE password=encrypt(:password, password)), but you can also specify any hash supported by passlib as the password_hash to perform the comparison in Python (that’s why we need the stored password hash from the database). You need to pip install passlib to use this feature.

Set up HTTP service

Then you need to set up an HTTP server, either with a dedicated process:

$ nginx-db-auth-serve --host localhost --port 8899 --config /path/to/config

or as a CGI script, if you have infrastructure for that set up anyway. Here’s an example apache configuration snippet to do this:

ScriptAlias /nginx-auth /path/to/nginxdbauth/nginx-db-auth-cgi
<Location /nginx-auth>
  SetEnv NGINXDBAUTH_CONFIG /path/to/config
  CGIPassAuth On  # apache >= 2.4.13
  # SetEnv NGINXDBAUTH_LOGFILE /path/to/log  # optional, for debugging
</Location>

Configure nginx

Now you can set up a protected nginx location like this:

location /private/ {
    auth_request /auth;
    # ... define rest of location ...
}

location = /auth {
    proxy_pass http://localhost:8899;  # or http://mycgi/nginx-auth
    proxy_pass_request_body off;
    proxy_set_header Content-Length "";
    proxy_set_header X-Required-Role "superuser";
    proxy_set_header WWW-Authenticate "Basic realm=\"my realm\"";
}

The WWW-Authenticate header sent by nginx will simply be echoed back on 401 requests (since as far as I can tell, nginx does not provide another way to set the realm string in the auth_request case).

CHANGES

1.1.1 (2024-06-10)

Changes

• Work around passlib/bcrypt bug (passlib)

1.1.0 (2023-03-19)

Changes

• Make sqlalchemy options configurable (dbconfig)

• Connect to database once on startup, not for each request (dbconnect)

• Drop Python-2 support (py2)

1.0.4 (2023-02-07)

• Update to sqlalchemy-2

1.0.3 (2022-05-04)

• Fix passlib import error

1.0.2 (2018-03-28)

• Echo back the WWW-Authenticate header for 401 responses.

1.0.1 (2018-03-28)

• Enable logging errors to a file for debugging the CGI script.

1.0.0 (2018-03-27)

• First release.