/utils/telemetryConsole

The telemetryConsole module exports the ConsoleTraceProcessor which logs one object per trace to the console.

The telemetry module registers the processor with the OTEL_TRACES_EXPORTER=console process environment variable.

A trace is logged once the root span of the trace ends. For a request the root span is the request span. The logged object has a summary of the count and total duration for each span name, and the span tree with nested children.

{
  name: 'GET /api/workspace{/:key}',
  start: 0,
  duration: 41.2,
  attributes: { 'faas.coldstart': true, 'xyz.workspace.key': 'locale', ... },
  summary: {
    'workspace.getLocale': { count: 1, duration: 38.6 },
    'workspace.composeObj': { count: 12, duration: 30.1 },
  },
  children: [ { name: 'workspace.getLocale', start: 1.8, duration: 38.6, children: [...] } ]
}

Start times and durations are in milliseconds. The start of each span is relative to the start of the root span. The summary duration of nested spans with the same name will be counted more than once, eg. a nested getLocale.

Traces whose root span is shorter than the minDuration option are not logged. The telemetry module assigns the minDuration from the OTEL_CONSOLE_MIN_DURATION process environment variable, eg. 500 to only log requests which take 500ms or longer.

The trace is logged as indented JSON if the process output is an interactive terminal. Otherwise, eg. in Vercel runtime logs, every trace is logged as a single line of JSON.

Spans which end after their root span, eg. a nonblocking query, are logged on their own if their trace was logged.

The resource attributes with the process metadata are only logged with the first trace of the process.

With the html option every logged trace is also written to an HTML report file with the most recent traces. The telemetry module assigns the html option from the OTEL_CONSOLE_HTML process environment variable in a local process. Keep the report open in a browser and reload the page after a request.

Traces are only written to the HTML report and not logged to the console with the log option set to false. The telemetry module assigns the log option false with the OTEL_TRACES_EXPORTER=html process environment variable. Spans which end after their root span are not written to the report and therefore not shown at all.