This is in the context of mainlining the Tchap fork of Synapse. Currently in Tchap usernames are derived from the user's email address (extracted from the UIA results, more specifically the m.login.email.identity step).
This change also exports the check_username method from the registration handler as part of the module API, so that a module can check if the username it's trying to generate is correct and doesn't conflict with an existing one, and fallback gracefully if not.

Co-authored-by: David Robertson <davidr@element.io>

This is some odds and ends found during the review of #11791
and while continuing to work in this code:

* Return attrs classes instead of dictionaries from some methods
  to improve type safety.
* Call `get_bundled_aggregations` fewer times.
* Adds a missing assertion in the tests.
* Do not return empty bundled aggregations for an event (preferring
  to not include the bundle at all, as the docstring states).

* Don't print HTTPStatus.* in "Processed..." logs

Fixes #11812. See also #7118 and
https://github.com/matrix-org/synapse/pull/7188#r401719326

 in
particular.

Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

This is mostly motivated by the tchap use case, where usernames are automatically generated from the user's email address (in a way that allows figuring out the email address from the username). Therefore, it's an issue if we respond to requests on /register and /register/available with M_USER_IN_USE, because it can potentially leak email addresses (which include the user's real name and place of work).

This commit adds a flag to inhibit the M_USER_IN_USE errors that are raised both by /register/available, and when providing a username early into the registration process. This error will still be raised if the user completes the registration process but the username conflicts. This is particularly useful when using modules (https://github.com/matrix-org/synapse/pull/11790 adds a module callback to set the username of users at registration) or SSO, since they can ensure the username is unique.

More context is available in the PR that introduced this behaviour to synapse-dinsic: matrix-org/synapse-dinsic#48 - as well as the issue in the matrix-dinsic repo: matrix-org/matrix-dinsic#476

Similar to #11817.

In `_create_power_level_validator` we
- retrieve `validator`. This is a class implementing the
  `jsonschema.protocols.Validator` interface. In other words,
  `validator: Type[jsonschema.protocols.Validator]`.
- we then create an second validator class by modifying the original
  `validator`. We return that class, which is also of type
  `Type[jsonschema.protocols.Validator]`.

So the original annotation was incorrect: it claimed we were returning
an instance of jsonSchema.Draft7Validator, not the class (or a subclass)
itself. (Strictly speaking this is incorrect, because `POWER_LEVELS_SCHEMA`
isn't pinned to a particular version of JSON Schema. But there are other
complications with the type stubs if you try to fix this; I felt like
the change herein was a decent compromise that better expresses intent).

(I suspect/hope the typeshed project would welcome an effort to improve
the jsonschema stubs. Let's see if I get some spare time.)

* add check that gc.freeze is available before calling

* newsfragment

* lint

* Update comment

Co-authored-by: Dan Callahan <danc@element.io>

Co-authored-by: Dan Callahan <danc@element.io>

* CI: run Complement on the VM, not inside Docker

This requires https://github.com/matrix-org/complement/pull/289



We now run Complement on the VM instead of inside a Docker container.
This is to allow Complement to bind to any high-numbered port when it
starts up its own federation servers. We want to do this to allow for
more concurrency when running complement tests. Previously, Complement
only ever bound to `:8448` when running its own federation server. This
prevented multiple federation tests running at the same time as they would
fight each other on the port. This did however allow Complement to run
in Docker, as the host could just port forward `:8448` to allow homeserver
containers to communicate to Complement. Now that we are using random
ports however, we cannot use Docker to run Complement. This ends up
being a good thing because:
 - Running Complement tests locally is closer to how they run in CI.
 - Allows the `CI` env var to be removed in Complement.
 - Slightly speeds up runs as we don't need to pull down the Complement
   image prior to running tests. This assumes GHA caches actions sensibly.

* Changelog

* Full stop

* Update .github/workflows/tests.yml

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

* Review comments

* Update .github/workflows/tests.yml

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

* Make functions in python deltas optional

It's annoying to always have to write stubs for these.

* Documentation for delta files

* changelog

* Docs: add missing PR submission process how-tos

The documentation says that in order to submit a pull request you have to run the linter and links to [Run the linters](https://matrix-org.github.io/synapse/latest/development/contributing_guide.html#run-the-linters).  IMO "Run the linters" should explain that development dependencies are a pre-requisite.

I also included `pip install wheel`  which I had to run inside my virtual environment on ubuntu before I `pip install -e ".[all,dev]"` would succeed.

Synapse 1.51.0 (2022-01-25)
===========================

No significant changes since 1.51.0rc2.

Synapse 1.51.0 deprecates `webclient` listeners and non-HTTP(S) `web_client_location`s. Support for these will be removed in Synapse 1.53.0, at which point Synapse will not be capable of directly serving a web client for Matrix.

Synapse 1.51.0rc2 (2022-01-24)
==============================

Bugfixes
--------

- Fix a bug introduced in Synapse 1.40.0 that caused Synapse to fail to process incoming federation traffic after handling a large amount of events in a v1 room. ([\#11806](https://github.com/matrix-org/synapse/issues/11806))

Synapse 1.51.0rc1 (2022-01-21)
==============================

Features
--------

- Add `track_puppeted_user_ips` config flag to record client IP addresses against puppeted users, and include the puppeted users in monthly active user counts. ([\#11561](https://github.com/matrix-org/synapse/issues/11561), [\#11749](https://github.com/matrix-org/synapse/issues/11749), [\#11757](https://github.com/matrix-org/synapse/issues/11757))
- Include whether the requesting user has participated in a thread when generating a summary for [MSC3440](https://github.com/matrix-org/matrix-doc/pull/3440). ([\#11577](https://github.com/matrix-org/synapse/issues/11577))
- Return an `M_FORBIDDEN` error code instead of `M_UNKNOWN` when a spam checker module prevents a user from creating a room. ([\#11672](https://github.com/matrix-org/synapse/issues/11672))
- Add a flag to the `synapse_review_recent_signups` script to ignore and filter appservice users. ([\#11675](https://github.com/matrix-org/synapse/issues/11675), [\#11770](https://github.com/matrix-org/synapse/issues/11770))

Bugfixes
--------

- Fix a long-standing issue which could cause Synapse to incorrectly accept data in the unsigned field of events
  received over federation. ([\#11530](https://github.com/matrix-org/synapse/issues/11530))
- Fix a long-standing bug where Synapse wouldn't cache a response indicating that a remote user has no devices. ([\#11587](https://github.com/matrix-org/synapse/issues/11587))
- Fix an error that occurs whilst trying to get the federation status of a destination server that was working normally. This admin API was newly introduced in Synapse v1.49.0. ([\#11593](https://github.com/matrix-org/synapse/issues/11593))
- Fix bundled aggregations not being included in the `/sync` response, per [MSC2675](https://github.com/matrix-org/matrix-doc/pull/2675). ([\#11612](https://github.com/matrix-org/synapse/issues/11612), [\#11659](https://github.com/matrix-org/synapse/issues/11659), [\#11791](https://github.com/matrix-org/synapse/issues/11791))
- Fix the `/_matrix/client/v1/room/{roomId}/hierarchy` endpoint returning incorrect fields which have been present since Synapse 1.49.0. ([\#11667](https://github.com/matrix-org/synapse/issues/11667))
- Fix preview of some GIF URLs (like tenor.com). Contributed by Philippe Daouadi. ([\#11669](https://github.com/matrix-org/synapse/issues/11669))
- Fix a bug where only the first 50 rooms from a space were returned from the `/hierarchy` API. This has existed since the introduction of the API in Synapse v1.41.0. ([\#11695](https://github.com/matrix-org/synapse/issues/11695))
- Fix a bug introduced in Synapse v1.18.0 where password reset and address validation emails would not be sent if their subject was configured to use the 'app' template variable. Contributed by @br4nnigan. ([\#11710](https://github.com/matrix-org/synapse/issues/11710), [\#11745](https://github.com/matrix-org/synapse/issues/11745))
- Make the 'List Rooms' Admin API sort stable. Contributed by Daniël Sonck. ([\#11737](https://github.com/matrix-org/synapse/issues/11737))
- Fix a long-standing bug where space hierarchy over federation would only work correctly some of the time. ([\#11775](https://github.com/matrix-org/synapse/issues/11775))
- Fix a bug introduced in Synapse v1.46.0 that prevented `on_logged_out` module callbacks from being correctly awaited by Synapse. ([\#11786](https://github.com/matrix-org/synapse/issues/11786))

Improved Documentation
----------------------

- Warn against using a Let's Encrypt certificate for TLS/DTLS TURN server client connections, and suggest using ZeroSSL certificate instead. This works around client-side connectivity errors caused by WebRTC libraries that reject Let's Encrypt certificates. Contibuted by @AndrewFerr. ([\#11686](https://github.com/matrix-org/synapse/issues/11686))
- Document the new `SYNAPSE_TEST_PERSIST_SQLITE_DB` environment variable in the contributing guide. ([\#11715](https://github.com/matrix-org/synapse/issues/11715))
- Document that the minimum supported PostgreSQL version is now 10. ([\#11725](https://github.com/matrix-org/synapse/issues/11725))
- Fix typo in demo docs: differnt. ([\#11735](https://github.com/matrix-org/synapse/issues/11735))
- Update room spec URL in config files. ([\#11739](https://github.com/matrix-org/synapse/issues/11739))
- Mention `python3-venv` and `libpq-dev` dependencies in the contribution guide. ([\#11740](https://github.com/matrix-org/synapse/issues/11740))
- Update documentation for configuring login with Facebook. ([\#11755](https://github.com/matrix-org/synapse/issues/11755))
- Update installation instructions to note that Python 3.6 is no longer supported. ([\#11781](https://github.com/matrix-org/synapse/issues/11781))

Deprecations and Removals
-------------------------

- Remove the unstable `/send_relation` endpoint. ([\#11682](https://github.com/matrix-org/synapse/issues/11682))
- Remove `python_twisted_reactor_pending_calls` Prometheus metric. ([\#11724](https://github.com/matrix-org/synapse/issues/11724))
- Remove the `password_hash` field from the response dictionaries of the [Users Admin API](https://matrix-org.github.io/synapse/latest/admin_api/user_admin_api.html). ([\#11576](https://github.com/matrix-org/synapse/issues/11576))
- **Deprecate support for `webclient` listeners and non-HTTP(S) `web_client_location` configuration. ([\#11774](https://github.com/matrix-org/synapse/issues/11774), [\#11783](https://github.com/matrix-org/synapse/issues/11783))**

Internal Changes
----------------

- Run `pyupgrade --py37-plus --keep-percent-format` on Synapse. ([\#11685](https://github.com/matrix-org/synapse/issues/11685))
- Use buildkit's cache feature to speed up docker builds. ([\#11691](https://github.com/matrix-org/synapse/issues/11691))
- Use `auto_attribs` and native type hints for attrs classes. ([\#11692](https://github.com/matrix-org/synapse/issues/11692), [\#11768](https://github.com/matrix-org/synapse/issues/11768))
- Remove debug logging for #4422, which has been closed since Synapse 0.99. ([\#11693](https://github.com/matrix-org/synapse/issues/11693))
- Remove fallback code for Python 2. ([\#11699](https://github.com/matrix-org/synapse/issues/11699))
- Add a test for [an edge case](https://github.com/matrix-org/synapse/pull/11532#discussion_r769104461) in the `/sync` logic. ([\#11701](https://github.com/matrix-org/synapse/issues/11701))
- Add the option to write SQLite test dbs to disk when running tests. ([\#11702](https://github.com/matrix-org/synapse/issues/11702))
- Improve Complement test output for Gitub Actions. ([\#11707](https://github.com/matrix-org/synapse/issues/11707))
- Fix docstring on `add_account_data_for_user`. ([\#11716](https://github.com/matrix-org/synapse/issues/11716))
- Complement environment variable name change and update `.gitignore`. ([\#11718](https://github.com/matrix-org/synapse/issues/11718))
- Simplify calculation of Prometheus metrics for garbage collection. ([\#11723](https://github.com/matrix-org/synapse/issues/11723))
- Improve accuracy of `python_twisted_reactor_tick_time` Prometheus metric. ([\#11724](https://github.com/matrix-org/synapse/issues/11724), [\#11771](https://github.com/matrix-org/synapse/issues/11771))
- Minor efficiency improvements when inserting many values into the database. ([\#11742](https://github.com/matrix-org/synapse/issues/11742))
- Invite PR authors to give themselves credit in the changelog. ([\#11744](https://github.com/matrix-org/synapse/issues/11744))
- Add optional debugging to investigate [issue 8631](https://github.com/matrix-org/synapse/issues/8631). ([\#11760](https://github.com/matrix-org/synapse/issues/11760))
- Remove `log_function` utility function and its uses. ([\#11761](https://github.com/matrix-org/synapse/issues/11761))
- Add a unit test that checks both `client` and `webclient` resources will function when simultaneously enabled. ([\#11765](https://github.com/matrix-org/synapse/issues/11765))
- Allow overriding complement commit using `COMPLEMENT_REF`. ([\#11766](https://github.com/matrix-org/synapse/issues/11766))
- Add some comments and type annotations for `_update_outliers_txn`. ([\#11776](https://github.com/matrix-org/synapse/issues/11776))

* Fix get federation status of destination if no error occured

PyNaCl's recent 1.5.0 release on PyPi includes arm64 wheels, which means our
arm64 docker images now build in a sensible amount of time, so we can skip the
amd64-only build.

This prevents the URL preview code from reading
a stream forever.

Images which are data URLs will no longer break URL
previews and will properly be "downloaded" and
thumbnailed.

Synapse 1.51.0rc2 (2022-01-24)
==============================

Bugfixes
--------

- Fix a bug introduced in Synapse 1.40.0 that caused Synapse to fail to process incoming federation traffic after handling a large amount of events in a v1 room. ([\#11806](https://github.com/matrix-org/synapse/issues/11806))

Remove account data (including client config, push rules and ignored users) upon user deactivation. (#11621)

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

Co-authored-by: Brendan Abolivier <babolivier@matrix.org>
Co-authored-by: Richard van der Hoff <richard@matrix.org>

Co-authored-by: Brendan Abolivier <babolivier@matrix.org>
Co-authored-by: Richard van der Hoff <richard@matrix.org>

* remove reference in comments to python3.6

* upgrade tox python env in script

* bump python version in example for completeness

* upgrade python version requirement in setup doc

* upgrade necessary python version in __init__.py

* upgrade python version in setup.py

* newsfragment

* drops refs to bionic and replace with focal

* bump refs to postgres 9.6 to 10

* fix hanging ci

* try installing tzdata first

* revert change made in b979f336

* ignore new random mypy error while debugging other error

* fix lint error for temporary workaround

* revert change to install list

* try passing env var

* export debian frontend var?

* move line and add comment

* bump pillow dependency

* bump lxml depenency

* install libjpeg-dev for pillow

* bump automat version to one compatible with py3.8

* add libwebp for pillow

* bump twisted trunk python version

* change suffix of newsfragment

* remove redundant python 3.7 checks

* lint

The PR was cherrypicked into v1.51.0rc1.

Synapse 1.51.0rc1 (2022-01-21)
==============================

Features
--------

- Add `track_puppeted_user_ips` config flag to record client IP addresses against puppeted users, and include the puppeted users in monthly active user counts. ([\#11561](https://github.com/matrix-org/synapse/issues/11561), [\#11749](https://github.com/matrix-org/synapse/issues/11749), [\#11757](https://github.com/matrix-org/synapse/issues/11757))
- Include whether the requesting user has participated in a thread when generating a summary for [MSC3440](https://github.com/matrix-org/matrix-doc/pull/3440). ([\#11577](https://github.com/matrix-org/synapse/issues/11577))
- Return an `M_FORBIDDEN` error code instead of `M_UNKNOWN` when a spam checker module prevents a user from creating a room. ([\#11672](https://github.com/matrix-org/synapse/issues/11672))
- Add a flag to the `synapse_review_recent_signups` script to ignore and filter appservice users. ([\#11675](https://github.com/matrix-org/synapse/issues/11675), [\#11770](https://github.com/matrix-org/synapse/issues/11770))

Bugfixes
--------

- Fix a long-standing issue which could cause Synapse to incorrectly accept data in the unsigned field of events
  received over federation. ([\#11530](https://github.com/matrix-org/synapse/issues/11530))
- Fix a long-standing bug where Synapse wouldn't cache a response indicating that a remote user has no devices. ([\#11587](https://github.com/matrix-org/synapse/issues/11587))
- Fix an error that occurs whilst trying to get the federation status of a destination server that was working normally. This admin API was newly introduced in Synapse v1.49.0. ([\#11593](https://github.com/matrix-org/synapse/issues/11593))
- Fix bundled aggregations not being included in the `/sync` response, per [MSC2675](https://github.com/matrix-org/matrix-doc/pull/2675). ([\#11612](https://github.com/matrix-org/synapse/issues/11612), [\#11659](https://github.com/matrix-org/synapse/issues/11659), [\#11791](https://github.com/matrix-org/synapse/issues/11791))
- Fix the `/_matrix/client/v1/room/{roomId}/hierarchy` endpoint returning incorrect fields which have been present since Synapse 1.49.0. ([\#11667](https://github.com/matrix-org/synapse/issues/11667))
- Fix preview of some GIF URLs (like tenor.com). Contributed by Philippe Daouadi. ([\#11669](https://github.com/matrix-org/synapse/issues/11669))
- Fix a bug where only the first 50 rooms from a space were returned from the `/hierarchy` API. This has existed since the introduction of the API in Synapse v1.41.0. ([\#11695](https://github.com/matrix-org/synapse/issues/11695))
- Fix a bug introduced in Synapse v1.18.0 where password reset and address validation emails would not be sent if their subject was configured to use the 'app' template variable. Contributed by @br4nnigan. ([\#11710](https://github.com/matrix-org/synapse/issues/11710), [\#11745](https://github.com/matrix-org/synapse/issues/11745))
- Make the 'List Rooms' Admin API sort stable. Contributed by Daniël Sonck. ([\#11737](https://github.com/matrix-org/synapse/issues/11737))
- Fix a long-standing bug where space hierarchy over federation would only work correctly some of the time. ([\#11775](https://github.com/matrix-org/synapse/issues/11775))
- Fix a bug introduced in Synapse v1.46.0 that prevented `on_logged_out` module callbacks from being correctly awaited by Synapse. ([\#11786](https://github.com/matrix-org/synapse/issues/11786))

Improved Documentation
----------------------

- Warn against using a Let's Encrypt certificate for TLS/DTLS TURN server client connections, and suggest using ZeroSSL certificate instead. This works around client-side connectivity errors caused by WebRTC libraries that reject Let's Encrypt certificates. Contibuted by @AndrewFerr. ([\#11686](https://github.com/matrix-org/synapse/issues/11686))
- Document the new `SYNAPSE_TEST_PERSIST_SQLITE_DB` environment variable in the contributing guide. ([\#11715](https://github.com/matrix-org/synapse/issues/11715))
- Document that the minimum supported PostgreSQL version is now 10. ([\#11725](https://github.com/matrix-org/synapse/issues/11725))
- Fix typo in demo docs: differnt. ([\#11735](https://github.com/matrix-org/synapse/issues/11735))
- Update room spec URL in config files. ([\#11739](https://github.com/matrix-org/synapse/issues/11739))
- Mention `python3-venv` and `libpq-dev` dependencies in the contribution guide. ([\#11740](https://github.com/matrix-org/synapse/issues/11740))
- Update documentation for configuring login with Facebook. ([\#11755](https://github.com/matrix-org/synapse/issues/11755))
- Update installation instructions to note that Python 3.6 is no longer supported. ([\#11781](https://github.com/matrix-org/synapse/issues/11781))

Deprecations and Removals
-------------------------

- Remove the unstable `/send_relation` endpoint. ([\#11682](https://github.com/matrix-org/synapse/issues/11682))
- Remove `python_twisted_reactor_pending_calls` Prometheus metric. ([\#11724](https://github.com/matrix-org/synapse/issues/11724))
- Remove the `password_hash` field from the response dictionaries of the [Users Admin API](https://matrix-org.github.io/synapse/latest/admin_api/user_admin_api.html). ([\#11576](https://github.com/matrix-org/synapse/issues/11576))
- Deprecate support for `webclient` listeners and non-HTTP(S) `web_client_location` configuration. ([\#11774](https://github.com/matrix-org/synapse/issues/11774), [\#11783](https://github.com/matrix-org/synapse/issues/11783))

Internal Changes
----------------

- Run `pyupgrade --py37-plus --keep-percent-format` on Synapse. ([\#11685](https://github.com/matrix-org/synapse/issues/11685))
- Use buildkit's cache feature to speed up docker builds. ([\#11691](https://github.com/matrix-org/synapse/issues/11691))
- Use `auto_attribs` and native type hints for attrs classes. ([\#11692](https://github.com/matrix-org/synapse/issues/11692), [\#11768](https://github.com/matrix-org/synapse/issues/11768))
- Remove debug logging for #4422, which has been closed since Synapse 0.99. ([\#11693](https://github.com/matrix-org/synapse/issues/11693))
- Remove fallback code for Python 2. ([\#11699](https://github.com/matrix-org/synapse/issues/11699))
- Add a test for [an edge case](https://github.com/matrix-org/synapse/pull/11532#discussion_r769104461) in the `/sync` logic. ([\#11701](https://github.com/matrix-org/synapse/issues/11701))
- Add the option to write SQLite test dbs to disk when running tests. ([\#11702](https://github.com/matrix-org/synapse/issues/11702))
- Improve Complement test output for Gitub Actions. ([\#11707](https://github.com/matrix-org/synapse/issues/11707))
- Fix docstring on `add_account_data_for_user`. ([\#11716](https://github.com/matrix-org/synapse/issues/11716))
- Complement environment variable name change and update `.gitignore`. ([\#11718](https://github.com/matrix-org/synapse/issues/11718))
- Simplify calculation of Prometheus metrics for garbage collection. ([\#11723](https://github.com/matrix-org/synapse/issues/11723))
- Improve accuracy of `python_twisted_reactor_tick_time` Prometheus metric. ([\#11724](https://github.com/matrix-org/synapse/issues/11724), [\#11771](https://github.com/matrix-org/synapse/issues/11771))
- Minor efficiency improvements when inserting many values into the database. ([\#11742](https://github.com/matrix-org/synapse/issues/11742))
- Invite PR authors to give themselves credit in the changelog. ([\#11744](https://github.com/matrix-org/synapse/issues/11744))
- Add optional debugging to investigate [issue 8631](https://github.com/matrix-org/synapse/issues/8631). ([\#11760](https://github.com/matrix-org/synapse/issues/11760))
- Remove `log_function` utility function and its uses. ([\#11761](https://github.com/matrix-org/synapse/issues/11761))
- Add a unit test that checks both `client` and `webclient` resources will function when simultaneously enabled. ([\#11765](https://github.com/matrix-org/synapse/issues/11765))
- Allow overriding complement commit using `COMPLEMENT_REF`. ([\#11766](https://github.com/matrix-org/synapse/issues/11766))
- Add some comments and type annotations for `_update_outliers_txn`. ([\#11776](https://github.com/matrix-org/synapse/issues/11776))

... and start populating them for new events