tracing-flat-json

A simple tracing_subscriber::Layer emitting newline-delimited JSON, with all event and span fields flattened onto the top level JSON object. Similar to combining the json-subscriber options with_flattened_event and with_top_level_flattened_span_list, without the caveats about duplicate fields noted in the documentation for those options.

Usage

use tracing_subscriber::prelude::*;

tracing_subscriber::Registry::default()
    .with(tracing_flat_json::FlatJsonLayer::new(std::io::stdout))
    .init();

Feature Flags

• tracing-log: Handle log events emitted by tracing-log. Enabled by default.
• tracing-opentelemetry: Outputs the trace_id added to spans by tracing-opentelemetry. May not work when compiled with multiple versions of tracing-opentelemetry in the same executable.

Output Format

Included:

• timestamp (RFC3339 UTC)
• level
• trace_id (with feature tracing-opentelemetry)
• code.file.path
• code.line.number
• event message
• event fields, source code order
• parent span fields, source code order, latest span first, root span last

Excluded:

• span names
• target
• span_id
• duplicate fields (only latest value for each field name)