A set of changes to enable neon to work in IPv6 environments. The
changes are backward-compatible but allow to deploy neon even to
IPv6-only environments:
- bind to both IPv4 and IPv6 interfaces
- allow connections to Postgres from IPv6 interface
- parse the address from control plane that could also be IPv6
## Problem
wake_compute can fail sometimes but is eligible for retries. We retry
during the main connect, but not during auth.
## Summary of changes
retry wake_compute during auth flow if there was an error talking to
control plane, or if there was a temporary error in waking the compute
node
## Problem
Half of #4699.
TCP/WS have one implementation of `connect_to_compute`, HTTP has another
implementation of `connect_to_compute`.
Having both is annoying to deal with.
## Summary of changes
Creates a set of traits `ConnectMechanism` and `ShouldError` that allows
the `connect_to_compute` to be generic over raw TCP stream or
tokio_postgres based connections.
I'm not super happy with this. I think it would be nice to
remove tokio_postgres entirely but that will need a lot more thought to
be put into it.
I have also slightly refactored the caching to use fewer references.
Instead using ownership to ensure the state of retrying is encoded in
the type system.
## Problem
`cargo +nightly doc` is giving a lot of warnings: broken links, naked
URLs, etc.
## Summary of changes
* update the `proc-macro2` dependency so that it can compile on latest
Rust nightly, see https://github.com/dtolnay/proc-macro2/pull/391 and
https://github.com/dtolnay/proc-macro2/issues/398
* allow the `private_intra_doc_links` lint, as linking to something
that's private is always more useful than just mentioning it without a
link: if the link breaks in the future, at least there is a warning due
to that. Also, one might enable
[`--document-private-items`](https://doc.rust-lang.org/cargo/commands/cargo-doc.html#documentation-options)
in the future and make these links work in general.
* fix all the remaining warnings given by `cargo +nightly doc`
* make it possible to run `cargo doc` on stable Rust by updating
`opentelemetry` and associated crates to version 0.19, pulling in a fix
that previously broke `cargo doc` on stable:
https://github.com/open-telemetry/opentelemetry-rust/pull/904
* Add `cargo doc` to CI to ensure that it won't get broken in the
future.
Fixes#2557
## Future work
* Potentially, it might make sense, for development purposes, to publish
the generated rustdocs somewhere, like for example [how the rust
compiler does
it](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/index.html).
I will file an issue for discussion.
## Problem
It took me a while to understand the purpose of all the tasks spawned in
the main functions.
## Summary of changes
Utilising the type system and less macros, plus much more comments,
document the shutdown procedure of each task in detail
Prod logs have deep accidential span nesting. Introduced in #3759 and
has been untouched since, maybe no one watches proxy logs? :) I found it
by accident when looking to see if proxy logs have ansi colors with
`{neon_service="proxy"}`.
The solution is to mostly stop using `Span::enter` or `Span::entered` in
async code. Kept on `Span::entered` in cancel on shutdown related path.
- Add support for splitting async postgres_backend into read and write halfes.
Safekeeper needs this for bidirectional streams. To this end, encapsulate
reading-writing postgres messages to framed.rs with split support without any
additional changes (relying on BufRead for reading and BytesMut out buffer for
writing).
- Use async postgres_backend throughout safekeeper (and in proxy auth link
part).
- In both safekeeper COPY streams, do read-write from the same thread/task with
select! for easier error handling.
- Tidy up finishing CopyBoth streams in safekeeper sending and receiving WAL
-- join split parts back catching errors from them before returning.
Initially I hoped to do that read-write without split at all, through polling
IO:
https://github.com/neondatabase/neon/pull/3522
However that turned out to be more complicated than I initially expected
due to 1) borrow checking and 2) anon Future types. 1) required Rc<Refcell<...>>
which is Send construct just to satisfy the checker; 2) can be workaround with
transmute. But this is so messy that I decided to leave split.
To untie cyclic dependency between sync and async versions of postgres_backend,
copy QueryError and some logging/error routines to postgres_backend.rs. This is
temporal glue to make commits smaller, sync version will be dropped by the
upcoming commit completely.
On the surface, this doesn't add much, but there are some benefits:
* We can do graceful shutdowns and thus record more code coverage data.
* We now have a foundation for the more interesting behaviors, e.g. "stop
accepting new connections after SIGTERM but keep serving the existing ones".
* We give the otel machinery a chance to flush trace events before
finally shutting down.
This commit sets up OpenTelemetry tracing and exporter, so that they
can be exported as OpenTelemetry traces as well.
All outgoing HTTP requests will be traced. A separate (child)
span is created for each outgoing HTTP request, and the tracing
context is also propagated to the server in the HTTP headers.
If tracing is enabled in the control plane and compute node too, you
can now get an end-to-end distributed trace of what happens when a new
connection is established, starting from the handshake with the
client, creating the 'start_compute' operation in the control plane,
starting the compute node, all the way to down to fetching the base
backup and the availability checks in compute_ctl.
Co-authored-by: Dmitry Ivanov <dima@neon.tech>
Upstream proxy erroneously stores user & dbname in compute node info
cache entries, thus causing "funny" connection problems if such an entry
is reused while connecting to e.g. a different DB on the same compute node.
This PR fixes the problem but doesn't eliminate the root cause just yet.
I'll revisit this code and make it more type-safe in the upcoming PR.
This patch adds a timed LRU cache implementation and a compute node info cache on top of that.
Cache entries might expire on their own (default ttl=5mins) or become invalid due to real-world events,
e.g. compute node scale-to-zero event, so we add a connection retry loop with a wake-up call.
Solved problems:
- [x] Find a decent LRU implementation.
- [x] Implement timed LRU on top of that.
- [x] Cache results of `proxy_wake_compute` API call.
- [x] Don't invalidate newer cache entries for the same key.
- [x] Add cmdline configuration knobs (requires some refactoring).
- [x] Add failed connection estab metric.
- [x] Refactor auth backends to make things simpler (retries, cache
placement, etc).
- [x] Address review comments (add code comments + cleanup).
- [x] Retry `/proxy_wake_compute` if we couldn't connect to a compute
(e.g. stalled cache entry).
- [x] Add high-level description for `TimedLru`.
TODOs (will be addressed later):
- [ ] Add cache metrics (hit, spurious hit, miss).
- [ ] Synchronize http requests across concurrent per-client tasks
(https://github.com/neondatabase/neon/pull/3331#issuecomment-1399216069).
- [ ] Cache results of `proxy_get_role_secret` API call.
