Span processor for json logs

processor.js

export const processor = {
     /**
     * Forces to export all finished spans
     */
    forceFlush() { return Promise.resolve() },
    /**
     * Called when a {@link Span} is started, if the `span.isRecording()`
     * returns true.
     * @param span the Span that just started.
     */
    onStart() {},
    /**
     * Called when a {@link ReadableSpan} is ended, if the `span.isRecording()`
     * returns true.
     * @param {import('@opentelemetry/sdk-trace-base').ReadableSpan} span the Span that just ended.
     */
    onEnd(span) {
      const duration_ms = span.duration[0] * 1000 + span.duration[1] / 1000000;
      const startTime = new Date(span.startTime[0] * 1000 + Math.round(span.startTime[1] / 1000000));
      let kind = 'internal'
      switch (span.kind) {
        case SpanKind.CLIENT: kind = 'client'; break;
        case SpanKind.SERVER: kind = 'server'; break;
        case SpanKind.CONSUMER: kind = 'consumer'; break;
        case SpanKind.PRODUCER: kind = 'producer'; break;
      }
      const context = span.spanContext()
      console.log(JSON.stringify({
        'name': span.name,
        'duration_ms': duration_ms,
        'start_time': startTime.toISOString(),
        ...span.attributes,
        ...span.resource.attributes,
        'span.kind': kind,
        'library.name': span.instrumentationLibrary.name,
        'library.version': span.instrumentationLibrary.version,
        'trace.trace_id': context.traceId,
        'trace.span_id': context.spanId,
        'trace.parent_id': span.parentSpanId,
        'error': span.status.code !== 0,
        'status_message': span.status.message,
      }))
    }