Struct ECSLayerBuilder

pub struct ECSLayerBuilder { /* private fields */ }

Builder for a subscriber Layer writing ECS compatible json lines to a writer.

Example:

use tracing_ecs::ECSLayerBuilder;

// creates a minimal layer logging to stdout, and install it
ECSLayerBuilder::default()
    .stdout()
    .install()
    .unwrap();

Implementations

impl ECSLayerBuilder

pub fn with_extra_fields<F: Serialize>( self, extra_fields: F, ) -> Result<Self, Error>

pub fn with_attribute_mapper<M>(self, attribute_mapper: M) -> Self

where M: AttributeMapper,

pub fn with_span_events(self, span_events: FmtSpan) -> Self

Setup span events logging. Events supported: NEW, ENTER, EXIT, CLOSE.

Each configured span event (eg. enter span) will output a new log event line with an event object having the following attributes:

• kind: span
• action: either new, enter, exit or close

Example:

use tracing_ecs::ECSLayerBuilder;
use tracing_subscriber::fmt::format::FmtSpan;

ECSLayerBuilder::default()
    .with_span_events(FmtSpan::ENTER | FmtSpan::EXIT)
    .stdout()
    .install()
    .unwrap();

Event log line example:

{
    "@timestamp": "2025-07-24T08:24:19.733176000Z",
    "event": {
        "action": "enter",
        "kind": "span"
    },
    "span": {
        "id": "1",
        "name": "span_name"
    }
}

pub fn normalize_json(self, normalize_json: bool) -> Self

Control the normalization (keys de-dotting) of the generated json in the sense of https://www.elastic.co/guide/en/ecs/current/ecs-guidelines.html.

By default, normalization is enabled, thus logging host.hostname="localhost" will output:

{"host":{"hostname": "localhost"}}

With normalization disabled:

{"host.hostname": "localhost"}

Depending on your use case you may want to disable normalization if it’s done elsewhere in your log processing pipeline.

Benchmarks suggests a 30% speed up on log generation. (benches run on an Apple M2 Pro) it will also allocate less because, normalization recursively recreates a brand new json Value (not measured).

pub fn stderr(self) -> ECSLayer<fn() -> Stderr>

pub fn stdout(self) -> ECSLayer<fn() -> Stdout>

pub fn build_with_writer<W>(self, writer: W) -> ECSLayer<W>

where W: for<'writer> MakeWriter<'writer> + 'static,

Trait Implementations

impl Default for ECSLayerBuilder

fn default() -> Self

Returns the “default value” for a type.