## Problem
Some PrivateLink customers are unable to use Private DNS. As such they
use an invalid domain name to address Neon. We currently are rejecting
those connections because we cannot resolve the correct certificate.
## Summary of changes
1. Ensure a certificate is always returned.
2. If there is an SNI field, use endpoint fallback if it doesn't match.
I suggest reviewing each commit separately.
Both crates seem well maintained. x509-cert is part of the high quality
RustCrypto project that we already make heavy use of, and I think it
makes sense to reduce the dependencies where possible.
Closes: https://github.com/neondatabase/cloud/issues/22998
If control-plane reports that TLS should be used, load the certificates
(and watch for updates), make sure postgres use them, and detects
updates.
Procedure:
1. Load certificates
2. Reconfigure postgres/pgbouncer
3. Loop on a timer until certificates have loaded
4. Go to 1
Notes:
1. We only run this procedure if requested on startup by control plane.
2. We needed to compile pgbouncer with openssl enabled
3. Postgres doesn't allow tls keys to be globally accessible - must be
read only to the postgres user. I couldn't convince the autoscaling team
to let me put this logic into the VM settings, so instead compute_ctl
will copy the keys to be read-only by postgres.
4. To mitigate a race condition, we also verify that the key matches the
cert.
This upgrades the `proxy/` crate as well as the forked libraries in
`libs/proxy/` to edition 2024.
Also reformats the imports of those forked libraries via:
```
cargo +nightly fmt -p proxy -p postgres-protocol2 -p postgres-types2 -p tokio-postgres2 -- -l --config imports_granularity=Module,group_imports=StdExternalCrate,reorder_imports=true
```
It can be read commit-by-commit: the first commit has no formatting
changes, only changes to accomodate the new edition.
Part of #10918
Now that we construct the TLS client config for cancellation as well as
connect, it feels appropriate to construct the same config once and
re-use it elsewhere. It might also help should #7500 require any extra
setup, so we can easily add it to all the appropriate call sites.
