# RPC

HTTP RPC enables you to manage your Fluentd instance through HTTP endpoints. You can use this feature as a replacement of [Unix signals](https://docs.fluentd.org/deployment/signals).

It is especially useful for environments where signals are not supported well e.g. Windows. This requires Fluentd to start not with `--no-supervisor` command-line option.

## Configuration

By default, HTTP RPC is not enabled. To use this feature, set the `rpc_endpoint` option:

```
<system>
  rpc_endpoint 127.0.0.1:24444
</system>
```

Now, you can manage your Fluentd instance using an HTTP client:

```
$ curl http://127.0.0.1:24444/api/plugins.flushBuffers
{"ok":true}
```

As evident from the output above, each endpoint returns a JSON object as its response.

## HTTP Endpoints

| Endpoint                                    |                                                     Replacement of                                                    |                           Description                           | Version |
| ------------------------------------------- | :-------------------------------------------------------------------------------------------------------------------: | :-------------------------------------------------------------: | :-----: |
| `/api/processes.interruptWorkers`           |                              [SIGINT](https://docs.fluentd.org/signals#sigint-or-sigterm)                             |                        Stops the daemon.                        |   v1.0  |
| `/api/processes.killWorkers`                |                             [SIGTERM](https://docs.fluentd.org/signals#sigint-or-sigterm)                             |                        Stops the daemon.                        |   v1.0  |
| `/api/processes.zeroDowntimeRestart`        |                                  [SIGUSR2](https://docs.fluentd.org/signals#sigusr2)                                  | Restarts Fluentd with zero-downtime. (Not supported on Windows) |  v1.18  |
| `/api/processes.flushBuffersAndKillWorkers` | [SIGUSR1](https://docs.fluentd.org/signals#sigusr1) and [SIGTERM](https://docs.fluentd.org/signals#sigint-or-sigterm) |               Flushes buffer and stops the daemon.              |   v1.0  |
| `/api/plugins.flushBuffers`                 |                                  [SIGUSR1](https://docs.fluentd.org/signals#sigusr1)                                  |                  Flushes the buffered messages.                 |   v1.0  |
| `/api/config.reload`                        |                                   [SIGHUP](https://docs.fluentd.org/signals#sighup)                                   |                      Reloads configuration.                     |   v1.0  |
| `/api/config.gracefulReload`                |                                                          ---                                                          |                      Reloads configuration.                     |   v1.9  |

Appendix:

* `/api/config.gracefulReload`: This is the replacement of `SIGUSR2` before v1.18. Please use `/api/processes.zeroDowntimeRestart` or `/api/config.reload` unless there is a special reason. See [SIGUSR2](https://docs.fluentd.org/signals#sigusr2) for details.

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.