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in_http: add_remote_addr #2130

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90 changes: 79 additions & 11 deletions pipeline/inputs/http.md
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Original file line number Diff line number Diff line change
Expand Up @@ -5,17 +5,18 @@ The _HTTP_ input plugin lets Fluent Bit open an HTTP port that you can then rout

## Configuration parameters

| Key | Description | Default |
|----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------|-----------|
| `buffer_chunk_size` | This sets the chunk size for incoming JSON messages. These chunks are then stored and managed in the space available by `buffer_max_size`. | `512K` |
| `buffer_max_size` | Specify the maximum buffer size to receive a JSON message. | `4M` |
| `http2` | Enable HTTP/2 support. | `true` |
| `listen` | The address to listen on. | `0.0.0.0` |
| `port` | The port for Fluent Bit to listen on. | `9880` |
| `success_header` | Add an HTTP header key/value pair on success. Multiple headers can be set. For example, `X-Custom custom-answer`. | _none_ |
| `successful_response_code` | Allows setting successful response code. Supported values: `200`, `201`, and `204`. | `201` |
| `tag_key` | Specify the key name to overwrite a tag. If set, the tag will be overwritten by a value of the key. | _none_ |
| `threaded` | Indicates whether to run this input in its own [thread](../../administration/multithreading.md#inputs). | `false` |
| Key | Description | Default |
|----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------|-----------|
| `add_remote_addr` | Adds a `REMOTE_ADDR` field to the record. The value of `REMOTE_ADDR` is the client's address, which is extracted from the `X-Forwarded-For` header. | `false` |
| `buffer_chunk_size` | This sets the chunk size for incoming JSON messages. These chunks are then stored and managed in the space available by `buffer_max_size`. | `512K` |
| `buffer_max_size` | Specify the maximum buffer size to receive a JSON message. | `4M` |
| `http2` | Enable HTTP/2 support. | `true` |
| `listen` | The address to listen on. | `0.0.0.0` |
| `port` | The port for Fluent Bit to listen on. | `9880` |
| `success_header` | Add an HTTP header key/value pair on success. Multiple headers can be set. For example, `X-Custom custom-answer`. | _none_ |
| `successful_response_code` | Allows setting successful response code. Supported values: `200`, `201`, and `204`. | `201` |
| `tag_key` | Specify the key name to overwrite a tag. If set, the tag will be overwritten by a value of the key. | _none_ |
| `threaded` | Indicates whether to run this input in its own [thread](../../administration/multithreading.md#inputs). | `false` |

### TLS / SSL

Expand All @@ -41,6 +42,32 @@ For example, in the following curl message the tag set is `app.log` because the
curl -d '{"key1":"value1","key2":"value2"}' -XPOST -H "content-type: application/json" http://localhost:8888/app.log
```

### Add a remote address field

The `add_remote_addr` configuration parameter, when activated, adds a `REMOTE_ADDR` field to the records. The value of `REMOTE_ADDR` is the client's address, which is extracted from the `X-Forwarded-For` header.

In most cases, only a single `X-Forwarded-For` header is in the request, so the following curl would add a `REMOTE_ADDR` field which would be set to `host1`:

```shell
curl -d '{"key1":"value1"}' -XPOST -H 'Content-Type: application/json' -H 'X-Forwarded-For: host1, host2' http://localhost:8888
```

However, if your system sets multiple `X-Forwarded-For` headers in the request, the one used (first, or last) depends on the value of the `http2` parameter. For example:

Assuming the following X-Forwarded-For headers are in the request:

```text
X-Forwarded-For: host1, host2
X-Forwarded-For: host3, host4
```

The value of `REMOTE_ADDR` will be:

| http2 parameter | value of `REMOTE_ADDR` |
|------------------|------------------------|
| `true` (default) | host3 |
| `false` | host1 |
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@alexakreizinger alexakreizinger Jan 5, 2026

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| http2 parameter | value of `REMOTE_ADDR` |
|------------------|------------------------|
| `true` (default) | host3 |
| `false` | host1 |
| `http2` value | `REMOTE_ADDR` value |
| ------------- | ------------------- |
| `true` (default) | `host3` |
| `false` | `host1` |


### Configuration file

{% tabs %}
Expand Down Expand Up @@ -161,6 +188,47 @@ pipeline:
{% endtab %}
{% endtabs %}

#### Set `add_remote_addr`

The `add_remote_addr` configuration option lets you activate a feature that systematically adds the `REMOTE_ADDR` field to events, and set its value to the client's address. The address will be extracted from the `X-Forwarded-For` header of the request. The format is:

{% tabs %}
{% tab title="fluent-bit.yaml" %}

```yaml
pipeline:
inputs:
- name: http
listen: 0.0.0.0
port: 8888
add_remote_addr: true
outputs:
- name: stdout
```

{% endtab %}
{% tab title="fluent-bit.conf" %}

```text
[INPUT]
Name http
Listen 0.0.0.0
Port 8888
Add_remote_addr true

[OUTPUT]
Name stdout
```

{% endtab %}
{% endtabs %}

#### Example curl to test this feature

```shell
curl -d '{"key1":"value1"}' -XPOST -H 'Content-Type: application/json' -H 'X-Forwarded-For: host1, host2' http://localhost:8888
```

#### Set multiple custom HTTP headers on success

The `success_header` parameter lets you set multiple HTTP headers on success. The format is:
Expand Down