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Log retention is time based (APP_LOGS_RETENTION), so one chatty app can fill the disk or push everyone else’s history out. A budget caps the stored log bytes per app. When an app goes over, its oldest lines are trimmed. Other apps are never touched.

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Set a budget

Every app can have its own override, and a fleet default applies to apps without one.
In the dashboard, open Settings, Observability, Log volume and click the pencil on an app’s budget. The app’s Logs page shows the same field. A per-app value of 0, or clear, falls back to the fleet default. Changing a budget needs the same ability as enabling tracing.

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How trimming works

The hourly log retention sweep checks each app against its budget. An app over budget loses its oldest lines, in batches, until it is under. Each app drains a bounded amount per sweep (20,000 lines), so a very large backlog is worked down over several sweeps instead of blocking the database. Search stays consistent because trimmed lines leave the full text index at the same time. The running total of trimmed lines per app is kept and shown as Trimmed in the table.

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See the noisiest apps

The table lists apps noisiest first with stored size, line count, ingest rate (bytes per minute averaged over the last 24 hours), budget, percent used, forecast and trimmed lines. The forecast is days until the budget is reached at the current rate. It is empty when the app has no budget or is idle, and “Reached” when it is already at the limit. The same data is available at GET /api/v1/logs/usage, limited to apps the caller can read.

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Cost of the numbers

Usage is a pair of grouped aggregates over the log table (all rows, and the last 24 hours), computed once and cached for 30 seconds. Sizes count the message plus structured fields, not index overhead, so the on-disk footprint is somewhat larger than the budget.
Last modified on October 16, 2026