---
title: 'TestingBot Tunnel Logging: HTTP Logs, JSON Output, Request IDs'
description: 'Control TestingBot Tunnel logging: per-request HTTP logs with --log-http,
  separate levels for browser traffic and the Selenium relay, JSON output, request-id
  correlation and credential redaction.'
source_url:
  html: https://testingbot.com/support/tunnel/logging
  md: https://testingbot.com/support/tunnel/logging.md
---

# Quiet when it works, detailed when it fails

By default the tunnel logs only requests that fail or return a 5xx, with their headers. That keeps the log readable in normal use and self-diagnosing when a test breaks. When you need more, turn up browser traffic and the Selenium relay independently.

- Since v5.0 

## Where logs go and how much

| Option | Effect |
| --- | --- |
| -l,--logfile \<FILE\> | Also write the log to a file. |
| --log-level \<LEVEL\> | `error`, `warn`, `info` (default), `debug` or `trace`. |
| -d,--debug | Alias for `--log-level debug`. |
| --log-http \<MODE\> | Per-request HTTP logging, see below. |
| --log-format \<text\|json\> | Plain text (default) or one JSON object per record. |
| --request-id-header \<NAME\> | Header carrying the correlation id. Default `X-Request-Id`. |

```bash
java -jar testingbot-tunnel.jar --logfile tunnel.log --log-level debug
```

## HTTP request logging

`--log-http` controls how much of each proxied request is written to the log.

| Mode | Logs |
| --- | --- |
| errors | **Default.** Request line and headers, only for failed or 5xx responses. |
| none | Nothing per request. |
| url | One line per request. This was the 4.x behaviour. |
| headers | Every request with its headers. |

```bash
java -jar testingbot-tunnel.jar --log-http url
```

## Browser traffic and the Selenium relay, separately

The tunnel carries two kinds of traffic: the **proxy** (requests the cloud browser makes to your sites) and the **forwarder** (the Selenium relay on port 4445 that your test talks to). Set a level for each with `proxy:` and `forwarder:`.

```bash
# debugging a WebDriver problem: silence page traffic, show every command
java -jar testingbot-tunnel.jar --log-http proxy:none,forwarder:headers

# debugging a page that will not load: the opposite
java -jar testingbot-tunnel.jar --log-http proxy:headers,forwarder:none
```

`forwarder:body` also logs the relay's request body. That body is WebDriver capabilities, which routinely carry your access key, so it is redacted before it is written (see [redaction](https://testingbot.com#redaction)). `proxy:body` is refused: browser traffic has to stream and cannot be buffered for logging.

## Request IDs

Every request carries a correlation id. It is printed in brackets on each log line and passed to your server in the `X-Request-Id` header.

If the incoming request already has that header, its value is reused. That lets you match a line in the tunnel log to a line in your application's access log. Use a different header name if your stack expects one:

```bash
java -jar testingbot-tunnel.jar --request-id-header X-Correlation-Id
```

## JSON output

`--log-format json` writes one JSON object per record, so a log collector does not have to guess where a multi-line message or a stack trace ends.

```bash
java -jar testingbot-tunnel.jar --log-format json --logfile tunnel.jsonl
```

Useful when the tunnel runs in Docker or Kubernetes and its output is shipped to Loki, Elasticsearch, Datadog or CloudWatch.

## What is redacted

Tunnel logs often end up attached to support tickets and CI artifacts, so credentials are removed before anything is written.

- Header values that carry credentials, such as `Authorization`, `Proxy-Authorization`, cookies and `TB-Credentials`.
- Credentials in URLs: the `user:password@` part and credential-shaped query values.
- In `forwarder:body`, values whose key names look like credentials. A body that cannot be parsed, because of an unknown content type or because it is too large, is described rather than printed.

Sharing a log with support? Include the output of `--doctor` as well, it usually saves a round trip. See [troubleshooting](https://testingbot.com/support/tunnel/troubleshooting).

## Looking for more help?

Have questions or need more information? Reach out via email or Slack.

[Email us](https://testingbot.com/contact/new) [Join our Slack](https://join.slack.com/t/testingb0t/shared_invite/zt-3bcw9xch-jk19~6XPs_xBrsAgAedkCw)