As the proxy's functionality has grown, the HTTP routing functionality
has become complex. Module boundaries have become ill-defined, which
leads to tight coupling--especially around the `ctx` metadata types and
`Service` type signatures.
This change introduces a `Stack` type (and subcrate) that is used as the
base building block for proxy functionality. The `proxy` module now
exposes generic components--stack layers--that are configured and
instantiated in the `app::main` module.
This change reorganizes the repo as follows:
- Several auxiliary crates have been split out from the `src/` directory
into `lib/fs-watch`, `lib/stack` and `lib/task`.
- All logic specific to configuring and running the linkerd2 sidecar
proxy has been moved into `src/app`. The `Main` type has been moved
from `src/lib.rs` to `src/app/main.rs`.
- The `src/proxy` has reusable, generic components useful for building
proxies in terms of `Stack`s.
The logic contained in `lib/bind.rs`, pertaining to per-endpoint service
behavior, has almost entirely been moved into `app::main`.
`control::destination` has changed so that it is not responsible for
building services. (It used to take a clone of `Bind` and use it to
create per-endpoint services). Instead, the destination service
implements the new `proxy::Resolve` trait, which produces an infinite
`Resolution` stream for each lookup. This allows the `proxy::balance`
module to be generic over the servie discovery source.
Furthermore, the `router::Recognize` API has changed to only expose a
`recgonize()` method and not a `bind_service()` method. The
`bind_service` logic is now modeled as a `Stack`.
The `telemetry::http` module has been replaced by a
`proxy::http::metrics` module that is generic over its metadata types
and does not rely on the old telemetry event system. These events are
now a local implementation detail of the `tap` module.
There are no user-facing changes in the proxy's behavior.
The `tcp_connect_err` tests do not pass on Linux.
I initially observed that the errno produced is ECONNREFUSED on Linux,
not EXFULL, but even changing this does not help the test to pass
reliably, as the socket teardown semantics appear to be slightly
different.
In order to prevent spurious test failures during development, this
change marks these two tests as macos-specific.
Both tcp_connect_err tests frequently fail, even during local
development. This seems to happen because the proxy doesn't necessarily
observe the socket closure.
Instead of shutting down the socket gracefully, we can just drop it!
This helps the test pass much more reliably.
The proxy's telemetry system is implemented with a channel: the proxy thread
generates events and the control thread consumes these events to record
metrics and satisfy Tap observations. This design was intended to minimize
latency overhead in the data path.
However, this design leads to substantial CPU overhead: the control thread's
work scales with the proxy thread's work, leading to resource contention in
busy, resource-limited deployments. This design also has other drawbacks in
terms of allocation & makes it difficult to implement planned features like
payload-aware Tapping.
This change removes the event channel so that all telemetry is recorded
instantaneously in the data path, setting up for further simplifications so
that, eventually, the metrics registry properly uses service lifetimes to
support eviction.
This change has a potentially negative side effect: metrics scrapes obtain
the same lock that the data path uses to write metrics so, if the metrics
server gets heavy traffic, it can directly impact proxy latency. These
effects will be ameliorated by future changes that reduce the need for the
Mutex in the proxy thread.
This branch adds a label displaying the Unix error code name (or the raw
error code, on other operating systems or if the error code was not
recognized) to the metrics generated for TCP connection failures.
It also adds a couple of tests for label formatting.
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
There are various comments, examples, and documentation that refers to
Conduit. This change replaces or removes these refernces.
CONTRIBUTING.md has been updated to refer to GOVERNANCE/MAINTAINERS.
Fixeslinkerd/linkerd2#1276.
Currently, metrics with the `tls="no_identity"` label are duplicated.
This is because that label is generated from the `tls_status` label on
the `TransportLabels` struct, which is either `Some(())` or a
`ReasonForNoTls`. `ReasonForNoTls` has a
variant`ReasonForNoTls::NoIdentity`, which contains a
`ReasonForNoIdentity`, but when we format that variant as a label, we
always just produce the string "no_identity", regardless of the value of
the `ReasonForNoIdentity`.
However, label types are _also_ used as hash map keys into the map that
stores the metrics scopes, so although two instances of
`ReasonForNoTls::NoIdentity` with different `ReasonForNoIdentity`s
produce the same formatted label output, they aren't _equal_, since that
field differs, so they correspond to different metrics.
This branch resolves this issue, by adding an additional label to these
metrics, based on the `ReasonForNoIdentity`. Now, the separate lines in
the metrics output that correspond to each `ReasonForNoIdentity` have a
label differentiating them from each other.
Note that the the `NotImplementedForTap` and `NotImplementedForMetrics`
reasons will never show up in metrics labels, currently, since we don't gather
metrics from the tap and metrics servers at the moment.
Signed-off-by: Eliza Weisman <eliza@buoyant.io>
Sean McArthur
Oliver Gould
Markus Jais
Eliza Weisman