Enum DiscoverySource 

pub enum DiscoverySource {
    Static(Vec<String>),
    EnvPrefix(String),
    File(String),
    Dns {
        hostname: String,
        port: u16,
    },
    DnsSrv {
        record: String,
    },
    Consul {
        addr: String,
        service: String,
    },
    Docker {
        label: String,
        socket_path: String,
    },
    EtcdWatch {
        endpoints: Vec<String>,
        prefix: String,
    },
}

Available on non-WebAssembly only.

Controls how BackendPool discovers backend addresses.

Variants

Static(Vec<String>)

Fixed list of "host:port" addresses — never refreshed.

EnvPrefix(String)

Scan environment variables PREFIX_0, PREFIX_1, … until one is absent.

File(String)

Read one host:port per line from a file. Blank lines and lines starting with # are ignored.

Dns

Resolve hostname via A-record DNS lookup; format each IP as ip:port.

Fields

hostname: String

port: u16

DnsSrv

Resolve record (e.g. _http._tcp.example.com) via SRV lookup. Only the lowest-priority tier of records is used; within that tier each target:port is repeated weight.clamp(1, 20) times in the returned list so a plain round-robin consumer still sees proportional selection frequency — see [dns_srv] module docs for the exact algorithm and its bound.

Fields

record: String

Consul

Query a Consul agent’s /v1/health/service/:name endpoint. addr is host:port of the agent (e.g. 127.0.0.1:8500); only instances passing all health checks are returned.

Fields

addr: String

service: String

Docker

Query the Docker Engine API (over a Unix domain socket) for running containers carrying label, using each container’s value for that label as the backend address directly (e.g. rws.backend=10.0.0.5:8080) — see [docker] module docs for why the label value, not a published port guess, is the address. Unix-only; a no-op elsewhere.

Fields

label: String

socket_path: String

EtcdWatch

Watch an etcd v3 key prefix via its gRPC-gateway JSON/HTTP /v3/watch endpoint. Unlike every other source, this is not driven by the generic poll loop — BackendPool::start spawns a dedicated long-lived connection instead, applying PUT/DELETE events incrementally as they arrive rather than re-listing on each one. resolve() (and therefore plain refresh()) still performs a one-shot /v3/kv/range listing, so a pool built with this source is usable without ever calling start(), just without live updates. Plain HTTP only — no TLS support yet.

Fields

endpoints: Vec<String>

prefix: String