OpenTelemetry JSON stdout profile

otel-json emits one JSON object per line. This is an application stdout profile of the OpenTelemetry Logs Data Model; it is not OTLP/JSON. A log collector must apply the mapping below before exporting OTLP.

Record contract

JSON field	Type	OpenTelemetry field
timestamp	RFC 3339 UTC string	Timestamp
severity_text	string	SeverityText
severity_number	integer	SeverityNumber
body	string	Body
service.name	string	Resource.Attributes["service.name"]
logger	string	InstrumentationScope.Name
trace_id	optional 32-character lowercase hex string	TraceId
span_id	optional 16-character lowercase hex string	SpanId
all other fields	any JSON value	Attributes

Collectors must parse timestamp, move service.name to the resource, move logger to the instrumentation scope, decode valid trace and span identifiers, and retain every other application field as a log attribute.

Severity numbers use the OpenTelemetry bands: TRACE=1, DEBUG=5, INFO=9, WARN=13, ERROR=17, and FATAL=21. Zap DPANIC and PANIC retain their defined intermediate values, 18 and 19. severity_text uses these uppercase names; DPANIC and PANIC are retained where the source runtime exposes them.

Example:

{"timestamp":"2026-09-11T11:34:56.123Z","severity_text":"INFO","severity_number":9,"body":"request complete","logger":"maas-api","service.name":"maas-api","trace_id":"4bf92f3577b34da6a3ce929d0e0e4736","span_id":"00f067aa0ba902b7"}

Trace fields are omitted when no valid span is active.