* 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

This is a follow-up to #10565.

Preparation for dropping this table altogether. Part of #6574.

This is more efficient, since we only have to look up `state_key` in the event
dict once, rather than three (!) times.

Make the `get_global_account_data_by_type_for_user` cache be a tree-cache whose key is prefixed with the user ID (#11788)

To not change the behaviour during the deprecation period.

Follow-up to #11774.

#11595 dropped support for python 3.6, but forgot to update this doc.

This changes the behaviour of the root endpoint to redirect
directly to the configuration of `web_client_location` if it is
given an HTTP(S) URL.

Debug for #8631.

I'm having a hard time tracking down what's going wrong in that issue.
In the reported example, I could see server A sending federation traffic
to server B and all was well. Yet B reports out-of-sync device updates
from A.

I couldn't see what was _in_ the events being sent from A to B. So I
have added some crude logging to track

- when we have updates to send to a remote HS
- the edus we actually accumulate to send
- when a federation transaction includes a device list update edu
- when such an EDU is received

This is a bit of a sledgehammer.

Updates complement.sh to read the ref from an environment
variable (defaulting to master) when downloading a complement
bundle for testing.

`FederationClient.get_room_hierarchy()` caches its return values, so
refactor the code to avoid modifying the returned room summary.

A couple of surprises for me here, so thought I'd document them

By scraping Open Graph information from the HTML even
when an autodiscovery endpoint is found. The results are
then combined to capture as much information as possible
from the page.