docs: Add documentation for LANGFUSE_WEBHOOK_WHITELISTED_* environment variables

Author: csicar

pages/docs/prompt-management/features/webhooks-slack-integrations.mdx

@@ -218,3 +218,15 @@ export function verifyLangfuseSignature(
 </Tab>
 
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+
+
+# Troubleshooting
+
+For security reasons, langfuse will by default not allow users to make webhook requests to local ips oder internal hostnames.
+If you try, you might get one of these error messages:
+
+- `Blocked hostname detected`
+- `Blocked IP address detected: <some ip>`
+- `DNS lookup failed for <some hostname>`
+
+To resolve this problem set one of the corresponding `LANGFUSE_WEBHOOK_WHITELISTED_*` environment variables for the langfuse server. See [Configuration](/self-hosting/configuration) for details.

pages/self-hosting/configuration/index.mdx

@@ -70,6 +70,9 @@ Langfuse (self-hosted) has extensive configuration options via environment varia
 | `LANGFUSE_LOG_LEVEL`                            | `info`             | Set the log level for the application. Possible values are `trace`, `debug`, `info`, `warn`, `error`, `fatal`.                                                                                                                                                                                                                                                                                        |
 | `LANGFUSE_LOG_FORMAT`                           | `text`             | Set the log format for the application. Possible values are `text`, `json`.                                                                                                                                                                                                                                                                                                                           |
 | `LANGFUSE_LOG_PROPAGATED_HEADERS`               |                    | Comma-separated list of HTTP header names to propagate through logs via OpenTelemetry baggage. Header names are case-insensitive and will be normalized to lowercase. Useful for debugging and observability. Example: `x-request-id,x-user-id`.                                                                                                                                                      |
+| `LANGFUSE_WEBHOOK_WHITELISTED_HOST`             | `""`               | Comma-separated list of webhook hosts, that will not be validated. Use this for accessing local webhook servers.
+| `LANGFUSE_WEBHOOK_WHITELISTED_IPS`              | `""`               | Comma-separated list of webhook resolved ips, that will not be validated. Use this for accessing local webhook servers.
+| `LANGFUSE_WEBHOOK_WHITELISTED_IP_SEGMENTS`      | `""`               | Comma-separated list of local ip ranges, that are allowed to be used as webhook destinations, eventhough they would normally be forbidden by the security policy. Use CIDR syntax for specifying the ranges.
 
 ### Additional Features