---
layout: docs
page_title: Autoscaling Plugins
description: Plugins are used to architect the Nomad Autoscaler into distinct areas.
---

# Nomad Autoscaler Plugins

Plugins are an essential part of the Nomad Autoscaler architecture. The Autoscaler
uses the [go-plugin][go_plugin_github] library to implement an ecosystem of
different types of plugins. Each plugin type is responsible for a specific task:
APM plugins retrieve metrics about the workloads being monitored; strategy
plugins decide the scaling action to satisfy the scaling policy; and target
plugins perform the scaling action. The flexibility of plugins allows the Nomad
Autoscaler to be extended to meet specific business requirements or technology
use cases.

The Nomad Autoscaler currently ships with a number of built-in plugins to ease
the learning curve. Details of these can be found in the side menu, under the
specific plugin type sections. The autoscaler also supports external plugins; see
this list of [community-supported plugins][community_plugins].

# General Options

All plugins which require Nomad API connectivity support the parameters detailed
below. These plugins include Nomad APM, Nomad Target and all cluster scaling
targets.

- `nomad_config_inherit` `(bool: true)` - A boolean flag which indicates whether
  the plugin should inherit the agents Nomad configuration parameters. Plugins
  can override individual parameters and have their Nomad configuration merged
  with that of the agent.

- `nomad_address` `(string: "")` - The address of the Nomad server in the form
  of `protocol://addr:port`.

- `nomad_region` `(string: "")` - The region of the Nomad servers to connect with.

- `nomad_namespace` `(string: "")` - The target namespace for queries and actions
  bound to a namespace.

- `nomad_token` `(string: "")` - The SecretID of an ACL token to use to authenticate
  API requests with.

- `nomad_http-auth` `(string: "")` - The authentication information to use when
  connecting to a Nomad API which is using HTTP authentication.

- `nomad_ca-cert` `(string: "")` - Path to a PEM encoded CA cert file to use to
  verify the Nomad server SSL certificate.

- `nomad_ca-path` `(string: "")` - Path to a directory of PEM encoded CA cert
  files to verify the Nomad server SSL certificate.

- `nomad_client-cert` `(string: "")` - Path to a PEM encoded client certificate
  for TLS authentication to the Nomad server.

- `nomad-client-key` `(string: "")` - Path to an unencrypted PEM encoded private
  key matching the client certificate.

- `nomad_tls-server-name` `(string: "")` - The server name to use as the SNI
  host when connecting via TLS.

- `nomad_skip-verify` `(string: "")` - Do not verify TLS certificates. This is
  strongly discouraged.

# Loading External Plugins

In order to utilise external plugins, the plugin binary must be downloaded to a
directory on the same host that the Nomad Autoscaler will run. This directory
should be referenced by the [plugin_dir][plugin_dir_config] config parameter along
with an appropriate [APM][apm], [Strategy][strategy] or [Target][target] block
entry.

[go_plugin_github]: https://github.com/hashicorp/go-plugin
[community_plugins]: /tools/autoscaling/plugins/external
[plugin_dir_config]: /tools/autoscaling/agent#plugin_dir
[apm]: /tools/autoscaling/agent/apm#apm-block
[strategy]: /tools/autoscaling/agent/strategy#strategy-block
[target]: /tools/autoscaling/agent/target#target-block
