fly-logs

Fly logs

Fetch

fly apps list                              # find the app name
fly logs -a <app>                          # live tail
fly logs -a <app> --no-tail | tail -200    # recent burst, non-blocking
fly logs -a <app> -i <machine-id>          # one machine only

fly logs tails by default; for analysis prefer --no-tail piped through grep so the command terminates.

Filter

fly logs -a <app> --no-tail | grep -iE 'error|traceback|exception' | tail -50
fly logs -a <app> --no-tail | grep ' 500 '       # server errors on requests
fly logs -a <app> --no-tail | grep '<endpoint>'  # one route's traffic

Read the result properly

• A traceback's LAST frame in app code (not library code) is where to look.
• Repeated identical errors every N seconds = a crash-looping background job or health check, not user traffic.
• Shape-mismatch / feature-names errors on prediction routes = FEATURE_COLS drift between serving and training repos; fix the sync, don't restart.
• For deeper analysis hand the evidence to the debugger subagent.