> For the complete documentation index, see [llms.txt](https://docs.fluentbit.io/manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/upstream-servers-section.md).

# Upstream Servers

The `Upstream Servers` section defines a group of endpoints, referred to as nodes, which are used by output plugins to distribute data in a round-robin fashion. This is particularly useful for plugins that require load balancing when sending data. Examples of plugins that support this capability include [Forward](https://docs.fluentbit.io/manual/pipeline/outputs/forward) and [Elasticsearch](https://docs.fluentbit.io/manual/pipeline/outputs/elasticsearch).

In YAML, this section is named `upstream_servers` and requires specifying a `name` for the group and a list of `nodes`. Below is an example that defines two upstream server groups: `forward-balancing` and `forward-balancing-2`:

```yaml
upstream_servers:
  - name: forward-balancing
    nodes:
      - name: node-1
        host: 127.0.0.1
        port: 43000

      - name: node-2
        host: 127.0.0.1
        port: 44000

      - name: node-3
        host: 127.0.0.1
        port: 45000
        tls: true
        tls_verify: false
        shared_key: secret

  - name: forward-balancing-2
    nodes:
      - name: node-A
        host: 192.168.1.10
        port: 50000

      - name: node-B
        host: 192.168.1.11
        port: 51000
```

### Key Concepts

* Nodes: Each node in the upstream\_servers group must specify a name, host, and port. Additional settings like tls, tls\_verify, and shared\_key can be configured as needed for secure communication.

### Usage Note

While the `upstream_servers` section can be defined globally, some output plugins may require the configuration to be specified in a separate YAML file. Be sure to consult the documentation for each specific output plugin to understand its requirements.

For more details, refer to the documentation of the respective output plugins.


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