### Background
As part of Element's plan to support a light form of vhosting (virtual
host) (multiple instances of Synapse in the same Python process), we're
currently diving into the details and implications of running multiple
instances of Synapse in the same Python process.
"Per-tenant logging" tracked internally by
https://github.com/element-hq/synapse-small-hosts/issues/48
### Prior art
Previously, we exposed `server_name` by providing a static logging
`MetadataFilter` that injected the values:
https://github.com/element-hq/synapse/blob/205d9e4fc4774850f34971469ae500e70119d17a/synapse/config/logger.py#L216
While this can work fine for the normal case of one Synapse instance per
Python process, this configures things globally and isn't compatible
when we try to start multiple Synapse instances because each subsequent
tenant will overwrite the previous tenant.
### What does this PR do?
We remove the `MetadataFilter` and replace it by tracking the
`server_name` in the `LoggingContext` and expose it with our existing
[`LoggingContextFilter`](https://github.com/element-hq/synapse/blob/205d9e4fc4774850f34971469ae500e70119d17a/synapse/logging/context.py#L584-L622)
that we already use to expose information about the `request`.
This means that the `server_name` value follows wherever we log as
expected even when we have multiple Synapse instances running in the
same process.
### A note on logcontext
Anywhere, Synapse mistakenly uses the `sentinel` logcontext to log
something, we won't know which server sent the log. We've been fixing up
`sentinel` logcontext usage as tracked by
https://github.com/element-hq/synapse/issues/18905
Any further `sentinel` logcontext usage we find in the future can be
fixed piecemeal as normal.
https://github.com/element-hq/synapse/blob/d2a966f922fdc95bc86f7fe55b7b54a9ab3f25c1/docs/log_contexts.md#L71-L81
### Testing strategy
1. Adjust your logging config to include `%(server_name)s` in the format
```yaml
formatters:
precise:
format: '%(asctime)s - %(server_name)s - %(name)s - %(lineno)d -
%(levelname)s - %(request)s - %(message)s'
```
1. Start Synapse: `poetry run synapse_homeserver --config-path
homeserver.yaml`
1. Make some requests (`curl
http://localhost:8008/_matrix/client/versions`, etc)
1. Open the homeserver logs and notice the `server_name` in the logs as
expected. `unknown_server_from_sentinel_context` is expected for the
`sentinel` logcontext (things outside of Synapse).
Fix a couple type annotations in the `RootConfig`/`Config`. Discovered
while cribbing this code for another project.
It's really sucks that `mypy` type checking doesn't catch this. I assume
this is because we also have a `synapse/config/_base.pyi` that overrides
all of this. Still unclear to me why the `Iterable[str]` vs
`StrSequence` issue wasn't caught as that's what `ConfigError` expects.
During the migration the automated script to update the copyright
headers accidentally got rid of some of the existing copyright lines.
Reinstate them.
This reverts #11019 and structures the code a bit more like it was before #10985.
The global cache state must be reset before running the tests since other test
cases might have configured caching (and thus touched the global state).
This removes the magic allowing accessing configurable
variables directly from the config object. It is now required
that a specific configuration class is used (e.g. `config.foo`
must be replaced with `config.server.foo`).
Part of #9744
Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.
`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>`
Devon Hudson