2 4 0 Custom Terraform Provider: Resource and CRUD (Go)

• This section walks through the Resource block and the logic flow of the CRUD functions in the main.go file in detail. As the code is quite long, each function is covered in its own subpage.

• Video 2 4 0

Code Notes

• Andrew finishes the development of the main.go file by flashing out the internal logic of Resource() and the CRUD functions. In this episode onwards, we'll be able to actually use the features we developed here in other terraform files.

• In this page, we will look into Resource() only.

• The source code: main.go

package main

import (
	"bytes"
	"encoding/json"
	"net/http"
	...
)

func main() {...}
type Config struct {...}
func provider() {...}
func validateUUID(...) {...}
func providerConfigure(...) {...}

func Resource() *schema.Resource {
	resource := &schema.Resource{
		CreateContext: resourceHouseCreate,
		ReadContext: resourceHouseRead,
		UpdateContext: resourceHouseUpdate,
		DeleteContext: resourceHouseDelete,
		Schema: map[string]*schema.Schema{
			"name": {
				Type: schema.TypeString,
				Required: true,
				Description: "Name of home",
			},
			"description": {
				Type: schema.TypeString,
				Required: true,
				Description: "Description of home",
			},
			"domain_name": {
				Type: schema.TypeString,
				Required: true,
				Description: "Domain name of home eg. *.cloudfront.net",
			},
			"town": {
				Type: schema.TypeString,
				Required: true,
				Description: "The town to which the home will belong to",
			},
			"content_version": {
				Type: schema.TypeInt,
				Required: true,
				Description: "The content version of the home",
			},
		},
	}
	return resource
}

Lines 23-50 Schema

• Line 16: The Resource() function returns a pointer (*) to the schema.Resource object.

  • The * operator is used to access the value stored at a particular address.

    • pointer argument: it points to the actual value. So if the value is updated, your functions are working with the updated value.

    • non-pointer argument: it is a copy of the argument. The copy’s value will stay the same even after the argument’s current value is updated.

    

• Line 22: inside the function, a variable resource is declared, which is schema.Resource object that has 4 CRUD functions and a map of Schema with 5 attributes.

  • These CRUD functions will allow us to make http requests to the API endpoints of the chosen cloud service. These requests contain instructions for provisioning cloud resources.

  • A map is a data type in Go which is equivalent to hash table, or a collection of key:value pairs.

    • Line 23-47: each key comes with 3 attributes (Type, Required, Description) which define the properties of the value that can be assigned to the key. All the attributes are the string type (schema.TypeString) except for the key content_version (schema.TypeInt).

Resources

• Development workflow documentation: 2.4.0 CRUD Resource