> ## Documentation Index
> Fetch the complete documentation index at: https://ngrok.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Log Action
> The Log action enables you to log metadata to ngrok's eventing system.
export const ConfigField = ({title, type, cel = false, defaultValue = false, required = false, children}) => {
const id = `config-${title.replace(/\.|\s|\*/g, "_")}`;
return
{title}
{type &&
{type}
}
{defaultValue &&
default:
{defaultValue}
}
{required &&
Required
}
{cel &&
Supports CEL
}
{children}
;
};
The **Log** Traffic Policy action enables you to leverage ngrok's
[eventing system](/obs) to introduce observability into your Traffic Policy
documents.
## Configuration reference
The [Traffic Policy](/traffic-policy/) configuration
reference for this action.
### Supported phases
* `on_tcp_connect`
* `on_http_request`
* `on_http_response`
### Action type
`log`
### Configuration fields
A key-value map of metadata that you would like to include in your events
for this action.
## Behavior
### Event logs
When this action is executed, the specified metadata will be collected on the
[tcp\_connection\_closed.v0](/obs/events/reference/#tcp-connection-closedv0) event
under the `traffic_policy.logs` key.
### Event logs
When this action is executed, the specified metadata will be collected on the
[http\_request\_complete.v0](/obs/events/reference/#http-request-completev0) event
under `traffic_policy.logs` key.
### Non-terminating action
This is a **Non-terminating action**. It does not return a response, and will allow Traffic Policy processing to continue to the next Action in the chain. All **Cloud Endpoint** Traffic Policies must end with a terminating action. This requirement does not apply to **Agent Endpoints**.
## Examples
### Logging with CEL interpolation
The following [Traffic Policy](/traffic-policy/)
configuration will log a message with the endpoint identifier for every request.
#### Example Traffic Policy document
```yaml policy.yml theme={null}
on_http_request:
- actions:
- type: log
config:
metadata:
message: Log action executed.
endpoint_id: ${endpoint.id}
```
```json policy.json theme={null}
{
"on_http_request": [
{
"actions": [
{
"type": "log",
"config": {
"metadata": {
"message": "Log action executed.",
"endpoint_id": "${endpoint.id}"
}
}
}
]
}
]
}
```
#### Example request
```bash theme={null}
$ curl https://example.ngrok.app
```
Once the request has completed, and you have properly configured an
event destination, you should see an event appear with the following payload:
```jsx theme={null}
{
"event_id": "ev_25X3yFS6TDkig1KDJWIc4nnJO0c",
"event_type": "http_request_complete.v0",
"event_timestamp": "2024-06-23T23:44:16Z",
"account_id": "ac_2OtNvAlhso10Gx6a7eupzX3F98q",
"object": {
"traffic_policy": {
"logs": [
{
"metadata": {
"message": "Log action executed.",
"endpoint_id": "ep_2bhsN2VP8W4pTkaMSrhyj0SRf8J"
}
}
]
}
}
}
```
## Action result variables
The following variables are made available for use in subsequent expressions and
CEL interpolations after the action has run. Variable values will only apply
to the last action execution, results are not concatenated.
A key-value map containing metadata that was logged during the action.
Each key represents a metadata attribute, and the value provides its
corresponding details.