> For the complete documentation index, see [llms.txt](https://v2.dataos.info/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://v2.dataos.info/concepts/resources/nilus/troubleshooting/checking-logs.md).

# Checking Logs

Logs are the fastest way to find the exact failure after metrics tell you which resource needs attention.

## What to capture

| Field                           | Why it matters                                                      |
| ------------------------------- | ------------------------------------------------------------------- |
| Resource name and `resource_id` | Connects logs, metrics, run history, and destination output.        |
| Tenant and owner                | Helps route follow-up and permissions checks.                       |
| Pipeline mode                   | Changes which source, sink, and state checks apply.                 |
| First error line                | Usually closer to the cause than later retries or cleanup messages. |
| Final status line               | Confirms whether the runtime failed before or after metrics push.   |

## Log level

Set Nilus runtime logging with `spec.logLevel` in the resource and the `LOG_LEVEL` environment variable inside the runtime. Use `INFO` for normal operation and raise to `DEBUG` only during focused investigation.

```yaml
spec:
  logLevel: INFO
```

## Useful patterns

Search for these patterns in the resource logs:

| Pattern                         | Meaning                                                                |
| ------------------------------- | ---------------------------------------------------------------------- |
| `Nilus app execution failed`    | The runtime raised an exception during pipeline execution.             |
| `Source not supported.`         | The source URI or pipeline mode did not resolve to a supported source. |
| `Sink not supported.`           | The destination URI did not resolve to a supported destination.        |
| `metrics push failed`           | Runtime metrics could not be pushed to Pushgateway.                    |
| `Final metrics push successful` | The runtime reached final metrics push after pipeline execution.       |
| `Final metrics push failed`     | The run completed or failed, but final metrics push also failed.       |

## Reading order

1. Start at the first error, not the final stack trace frame.
2. Look upward for the source or destination operation that triggered it.
3. Match the message to the source connector page, destination connector page, or common error catalog.
4. Check whether the same resource had a recent successful run.
5. Only change config after the failed stage is clear.

## Related docs

* [Troubleshooting](/concepts/resources/nilus/troubleshooting.md)
* [Common Errors](/concepts/resources/nilus/troubleshooting/common-errors.md)
* [Observability](/concepts/resources/nilus/observability.md)
* [Grafana Dashboards](/concepts/resources/nilus/observability/grafana-dashboard.md)


---

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