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Mads Kiilerich

auth: only use X- headers instead of wsgi.url_scheme if explicitly told so in url_scheme_header - drop https_fixup setting

Before, several X- headers would be trusted to overrule the actual connection
protocol (http or https) seen by the Kallithea WSGI server. That was mainly
when https_fixup were set, but it incorrectly also kicked in if https_fixup or
use_htsts were configured. The ambiguity of which headers were used also made
it less reliable. The proxy server not only had to be configured to set one of
the headers correctly, it also had to make sure other headers were not passed
on from the client. It would thus in some cases be possible for clients to fake
the connection scheme, and thus potentially be possible to bypass restrictions
configured in Kallithea.

Fixed by making it configurable which WSGI environment variable to use for the
protocol. Users can configure url_scheme_header to for example
HTTP_X_FORWARDED_PROTO instead of using the default wsgi.url_scheme .

This change is a bit similar to what is going on in the https_fixup middleware,
but is doing a bit more of what for example is happening in similar code in
werkzeug/middleware/proxy_fix.py .

The semantics of the old https_fixup were unsafe, so it has been dropped.
Admins that are upgrading must change their configuration to use the new
url_scheme_header option.

=======================
Database schema changes
=======================

Kallithea uses Alembic for :ref:`database migrations <upgrade_db>`
(upgrades and downgrades).

If you are developing a Kallithea feature that requires database schema
changes, you should make a matching Alembic database migration script:

1. :ref:`Create a Kallithea configuration and database <setup>` for testing
   the migration script, or use existing ``development.ini`` setup.

   Ensure that this database is up to date with the latest database
   schema *before* the changes you're currently developing. (Do not
   create the database while your new schema changes are applied.)

2. Create a separate throwaway configuration for iterating on the actual
   database changes::

    kallithea-cli config-create temp.ini

   Edit the file to change database settings. SQLite is typically fine,
   but make sure to change the path to e.g. ``temp.db``, to avoid
   clobbering any existing database file.

3. Make your code changes (including database schema changes in ``db.py``).

4. After every database schema change, recreate the throwaway database
   to test the changes::

    rm temp.db
    kallithea-cli db-create -c temp.ini --repos=/var/repos --user=doe --email doe@example.com --password=123456 --no-public-access --force-yes
    kallithea-cli repo-scan -c temp.ini

5. Once satisfied with the schema changes, auto-generate a draft Alembic
   script using the development database that has *not* been upgraded.
   (The generated script will upgrade the database to match the code.)

   ::

    alembic -c development.ini revision -m "area: add cool feature" --autogenerate

6. Edit the script to clean it up and fix any problems.

   Note that for changes that simply add columns, it may be appropriate
   to not remove them in the downgrade script (and instead do nothing),
   to avoid the loss of data. Unknown columns will simply be ignored by
   Kallithea versions predating your changes.

7. Run ``alembic -c development.ini upgrade head`` to apply changes to
   the (non-throwaway) database, and test the upgrade script. Also test
   downgrades.

   The included ``development.ini`` has full SQL logging enabled. If
   you're using another configuration file, you may want to enable it
   by setting ``level = DEBUG`` in section ``[handler_console_sql]``.

The Alembic migration script should be committed in the same revision as
the database schema (``db.py``) changes.

See the `Alembic documentation`__ for more information, in particular
the tutorial and the section about auto-generating migration scripts.

.. __: http://alembic.zzzcomputing.com/en/latest/


Troubleshooting
---------------

* If ``alembic --autogenerate`` responds "Target database is not up to
  date", you need to either first use Alembic to upgrade the database
  to the most recent version (before your changes), or recreate the
  database from scratch (without your schema changes applied).