101 lines
3.6 KiB
Markdown
101 lines
3.6 KiB
Markdown
---
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layout: "docs"
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page_title: "Plugin Basics"
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sidebar_current: "docs-plugins-basics"
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description: |-
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This page documents the basics of how the plugin system in Terraform works, and how to setup a basic development environment for plugin development if you're writing a Terraform plugin.
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---
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# Plugin Basics
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~> **Advanced topic!** Plugin development is a highly advanced
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topic in Terraform, and is not required knowledge for day-to-day usage.
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If you don't plan on writing any plugins, this section of the documentation is
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not necessary to read. For general use of Terraform, please see our
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[Intro to Terraform](/intro/index.html) and [Getting
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Started](/intro/getting-started/install.html) guides.
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This page documents the basics of how the plugin system in Terraform
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works, and how to setup a basic development environment for plugin development
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if you're writing a Terraform plugin.
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## How it Works
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Terraform providers and provisioners are provided via plugins. Each plugin
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exposes an implementation for a specific service, such as AWS, or provisioner,
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such as bash. Plugins are executed as a separate process and communicate with
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the main Terraform binary over an RPC interface.
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More details are available in
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[Internal Docs](/docs/internals/internal-plugins.html).
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The code within the binaries must adhere to certain interfaces.
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The network communication and RPC is handled automatically by higher-level
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Terraform libraries. The exact interface to implement is documented
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in its respective documentation section.
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## Installing a Plugin
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To install a plugin, put the binary somewhere on your filesystem, then
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configure Terraform to be able to find it. The configuration where plugins
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are defined is `~/.terraformrc` for Unix-like systems and
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`%APPDATA%/terraform.rc` for Windows.
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An example that configures a new provider is shown below:
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```hcl
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providers {
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privatecloud = "/path/to/privatecloud"
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}
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```
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The key `privatecloud` is the _prefix_ of the resources for that provider.
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For example, if there is `privatecloud_instance` resource, then the above
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configuration would work. The value is the name of the executable. This
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can be a full path. If it isn't a full path, the executable will be looked
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up on the `PATH`.
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## Developing a Plugin
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Developing a plugin is simple. The only knowledge necessary to write
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a plugin is basic command-line skills and basic knowledge of the
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[Go programming language](http://golang.org).
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-> **Note:** A common pitfall is not properly setting up a
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<code>$GOPATH</code>. This can lead to strange errors. You can read more about
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this [here](https://golang.org/doc/code.html) to familiarize
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yourself.
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Create a new Go project somewhere in your `$GOPATH`. If you're a
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GitHub user, we recommend creating the project in the directory
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`$GOPATH/src/github.com/USERNAME/terraform-NAME`, where `USERNAME`
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is your GitHub username and `NAME` is the name of the plugin you're
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developing. This structure is what Go expects and simplifies things down
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the road.
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With the directory made, create a `main.go` file. This project will
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be a binary so the package is "main":
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```golang
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package main
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import (
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"github.com/hashicorp/terraform/plugin"
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)
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func main() {
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plugin.Serve(new(MyPlugin))
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}
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```
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And that's basically it! You'll have to change the argument given to
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`plugin.Serve` to be your actual plugin, but that is the only change
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you'll have to make. The argument should be a structure implementing
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one of the plugin interfaces (depending on what sort of plugin
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you're creating).
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Terraform plugins must follow a very specific naming convention of
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`terraform-TYPE-NAME`. For example, `terraform-provider-aws`, which
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tells Terraform that the plugin is a provider that can be referenced
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as "aws".
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