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* Update for search engine optimization * Update descriptions and add intro body summary paragraph * Apply suggestions from code review Co-authored-by: Jeff Boruszak <104028618+boruszak@users.noreply.github.com> --------- Co-authored-by: Jeff Boruszak <104028618+boruszak@users.noreply.github.com>
82 lines
2.5 KiB
Plaintext
82 lines
2.5 KiB
Plaintext
---
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layout: docs
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page_title: Nomad Base Plugin
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description: |-
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Learn how to create a Nomad plugin so you can extend Nomad's task and device driver features. Review device plugin API functions that you must implement in your device plugin.
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---
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# Nomad Base Plugin
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This page provides conceptual information on Nomad's base plugin, which is a
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special plugin type implemented by all plugins. The base plugin allows for
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common plugin operations such as defining a configuration schema and version
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information.
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## Plugin API
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#### `PluginInfo() (*PluginInfoResponse, error)`
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A `PluginInfoResponse` contains meta data about the plugin.
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```go
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PluginInfoResponse{
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// Type is the plugin type which is implemented
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Type: PluginTypeDriver,
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// Plugin API versions supported by the plugin
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PluginApiVersions: []string{drivers.ApiVersion010},
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// Version of the plugin
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PluginVersion: "0.1.0",
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// Name of the plugin
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Name: "foodriver",
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}
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```
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#### `ConfigSchema() (*hclspec.Spec, error)`
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The `ConfigSchema` function allows a plugin to tell Nomad the schema for its
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configuration. This configuration is given in a [plugin block][pluginblock] of
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the client configuration. The schema is defined with the [hclspec][hclspec]
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package.
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#### `SetConfig(config *Config) error`
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The `SetConfig` function is called when starting the plugin for the first
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time. The `Config` given has two different configuration fields. The first
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`PluginConfig`, is an encoded configuration from the `plugin` block of the
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client config. The second, `AgentConfig`, is the Nomad agent's configuration
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which is given to all plugins.
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## HCL Specifications
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`*hclspec.Spec` is a struct that defines the schema to validate an HCL entity
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against. The full documentation of the different hcl attribute types can be
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found on the [hclspec godoc][hclspec].
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For a basic example, lets look at the driver configuration for the raw_exec
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driver:
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```hcl
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job "example" {
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...
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driver = "raw_exec"
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config {
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command = "/bin/sleep"
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args = ["100"]
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}
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}
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```
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The `config` block is what is validated against the `hclspec.Spec`. It has two
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keys, command which takes a string attribute and args which takes an array
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attribute. The corresponding `*hclspec.Spec` would be:
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```go
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spec := hclspec.NewObject(map[string]*hclspec.Spec{
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"command": hclspec.NewAttr("command", "string", true),
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"args": hclspec.NewAttr("args", "list(string)", false),
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})
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```
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[hclspec]: https://godoc.org/github.com/hashicorp/nomad/plugins/shared/hclspec
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[pluginblock]: /nomad/docs/configuration/plugin
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