Struct CanaryLayer 

pub struct CanaryLayer { /* private fields */ }

Available on non-WebAssembly only.

Weighted traffic-splitting proxy middleware.

Clone is cheap and shares state — all clones distribute traffic against the same underlying [CanaryState], so a CanaryLayer::update on one clone is immediately visible to a clone already wrapped into a running Application (see the module docs for the clone-before-wrapping pattern).

Implementations

impl CanaryLayer

pub fn new(backends: Vec<WeightedBackend>) -> CanaryLayer

Build a CanaryLayer from the given weighted backends.

Backends with weight == 0 are ignored. Equivalent to CanaryLayer::from_parts(backends, vec![]).

pub fn with_pools(pools: Vec<WeightedPool>) -> CanaryLayer

Build a CanaryLayer whose groups are all dynamically-discovered BackendPools rather than fixed URLs. Equivalent to CanaryLayer::from_parts(vec![], pools).

pub fn from_parts( backends: Vec<WeightedBackend>, pools: Vec<WeightedPool>, ) -> CanaryLayer

Build a CanaryLayer from a mix of fixed backends and dynamic pools.

pub fn add_pool(self, pool: BackendPool, weight: u32) -> CanaryLayer

Append one more dynamically-discovered group to an already-built layer (e.g. adding a canary BackendPool alongside stable backends passed to CanaryLayer::new). A weight of 0 is a no-op.

This is a builder method for use before .wrap(...) — for changing an already-wrapped, already-running layer’s configuration, use CanaryLayer::update instead.

pub fn update(&self, backends: Vec<WeightedBackend>, pools: Vec<WeightedPool>)

Replace the entire backend/pool configuration in place — the runtime equivalent of building a fresh layer with CanaryLayer::from_parts, except every existing clone of this layer (including one already wrapped into a running Application) picks up the change on its very next request. No restart required.

pub fn path_prefix(self, prefix: impl Into<String>) -> CanaryLayer

Only proxy requests whose URI starts with prefix; pass others through.

pub fn connect_timeout_ms(self, ms: u64) -> CanaryLayer

Override the TCP connect timeout (default: 5 000 ms).

pub fn read_timeout_ms(self, ms: u64) -> CanaryLayer

Override the response read timeout (default: 30 000 ms).

Trait Implementations

impl Clone for CanaryLayer

fn clone(&self) -> CanaryLayer

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Middleware for CanaryLayer

fn handle( &self, request: &Request, connection: &ConnectionInfo, next: &dyn Application, ) -> Result<Response, String>

fn runs_inline(&self, _request: &Request, _connection: &ConnectionInfo) -> bool

true when this layer’s own work for request never blocks (in-memory state, atomics, short mutexes) — see Application::runs_inline. A WithMiddleware stack runs inline only if every layer and the inner application agree. Default false.

fn is_passthrough( &self, _request: &Request, _connection: &ConnectionInfo, ) -> bool

true when handle would do nothing for request but call next (e.g. a rate limit that isn’t configured). A WithMiddleware stack offers the inner application’s execute_async only if every layer passes the request through. Default false.

fn accepts_streamed_body( &self, _request: &Request, _connection: &ConnectionInfo, ) -> bool

true when this layer never reads request.body, so the inner application may receive it as a stream (Application::streams_body). A layer that inspects the body (CSRF tokens in a form, request signatures, rewriting) must keep the default false: it would see an empty body.

fn answers_streamed_body( &self, _request: &Request, _connection: &ConnectionInfo, ) -> bool

true when this layer answers request itself — it doesn’t call next — and reads its body as a stream (a proxy forwarding it as it arrives). The body is then streamed whatever the layers after it and the application would say. Requires accepts_streamed_body. Since 18.3.0.

fn layer_name(&self) -> &'static str

A short name for this layer, as tools that describe an app list it (Application::middleware_names): by default the type’s name without its module path or generic parameters (CacheLayer). Since 18.28.0.