What is a Terraform Provider

A Terraform provider is a plugin that extends Terraform, allowing it to manage external resources such as cloud services. It serves as a mediator between Terraform and external APIs, using the Terraform Plugin Protocol (opens in a new tab) for communication.

Terraform providers, built with the terraform-plugin-framework (opens in a new tab), include:

Resources and Data Sources: described using a Terraform Type Schema, which is a map[string]Attribute, where an Attribute could be Primitive, Composite, or List.
Create, Read, Update and Delete methods: the interface through which the provider interacts with an external resource (usually an API) to reconcile a desired terraform specification with the actual state of the resource.
Plan Validators: defined to enable the validation of a desired specification at Plan-time, without making API calls to the external resource.
Plan Modifiers: defined to enable custom semantics around the Terraform Type Schema, and how it is reconciled with the external state to make a Plan.
Resource imports: defined to enable Terraform Specifications to be generated from existing resources.

A simple CRUD example

Let’s explore how to define a resource and map API operations to Terraform methods using annotations for CRUD actions.

Defining a Resource

Use x-speakeasy-entity to define a resource that you want to use terraform to manage.

Mapping API Operations to Resources Methods

An OpenAPI specification tracks a large list of Operation objects (opens in a new tab).

For a Terraform Provider generated by Speakeasy, the key element is the the x-speakeasy-entity-operation annotation. This annotation clarifies the purpose of each operation in terms of how it affects the associated remote entity.

openapi.yaml

  /drinks:
    post:
      x-speakeasy-entity-operation: Drink#create
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/Drink"
      responses:
        "200":
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Drink"
  /drinks/{id}:
    parameters:
      - name: id
        in: path
        required: true
        schema:
          type: string
    get:
      x-speakeasy-entity-operation: Drink#read
      responses:
        "200":
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Drink"
    post:
      x-speakeasy-entity-operation: Drink#update
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/Drink"
      responses:
        "200":
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Drink"
    delete:
      x-speakeasy-entity-operation: Drink#delete
      responses:
        "202":
          description: OK
components:
  schemas:
    Drink:
      x-speakeasy-entity: Drink
      type: object
      properties:
        name:
          description: The name of the drink.
          type: string
          examples:
            - Old Fashioned
            - Manhattan
            - Negroni
        type:
          $ref: "#/components/schemas/DrinkType"
        price:
          description: The price of one unit of the drink in US cents.
          type: number
          examples:
            - 1000 # $10.00
            - 1200 # $12.00
            - 1500 # $15.00
      required:
        - name
        - price

Managing Complex API Semantics with Speakeasy

APIs can have unique semantics not fully described by OpenAPI specs. To address this we have:

Inference Rules: Automatically derive most API semantics from the OpenAPI spec, with the exception of the x-speakeasy-entity-operation annotation.
OpenAPI Extensions: For more complex cases, use extensions to provide detailed configurations. These extensions are documented in the Terraform Extensions section of this documentation.
Support: Our engineering team continually updates inference rules and extensions to accommodate new API patterns.

Read more in our documentation here, or view more examples here.