View logs correlated to traces.

A trace tells you where time went. A log line tells you what the code thought was happening. They are usually in two places. Praytel joins them, so each log line sits under the span that emitted it.

Run it

praytel -- ./server           # append-only stream
praytel --tui -- ./server     # logs nested in the span tree

Example 1 shows the same app’s logs raw and then joined.

How a line gets joined

Praytel reads the child’s stdout and stderr line by line and accepts logs exported over OTLP. A line is attached to a span when it names one:

{"msg":"charge declined","trace_id":"e36345b5...","span_id":"afba9044..."}
level=warn msg="charge declined" trace_id=e36345b5... span_id=afba9044...

So the one change to make in your app is to put the active trace and span IDs on every log line. Most logging libraries have an OpenTelemetry hook that does this. Colour codes from pretty console writers are stripped before parsing.

Lines that cannot be joined

Unstructured lines are not an error; they are still shown. Praytel never guesses which span an untagged line belongs to. Instead:

• a line with no IDs goes to a global orphan group;
• a line with only a trace_id goes to that trace’s own orphan group;
• a line naming a span praytel has not seen yet waits for that span, or for the end of the run.

If the same message arrives on stdout and over OTLP, both copies are kept.

Reading the stream

stdout orphan          78db31e8... 7fa53bec... plain line
stdout checkout.Charge e36345b5... afba9044... {"msg":"grpc-span", ...}

The columns are the source (stdout, stderr or otlp), the span the line belongs to, the trace and span IDs, and the line itself. The stream only ever appends. A line that arrives before its span can be printed again once it has been joined.

Searching logs in the TUI

Press Tab to switch the search from traces to log bodies. Press Tab again to go back.

Limits

--max-log-lines caps retained lines (one million by default), with the same evict-then-shed behaviour as spans.

Next

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