req2schema

Generate a terraform provider resource Schema from an AWS request schema.

This tool is intended to supplement the Terraform AWS provider's skaff tool, focusing specifically on a resource's Schema. skaff does not use any external data to generate its source files, and instead populates a placeholder Schema. req2schema uses AWS HTTP request schemas to provide a stubbed out terraform resource schema with the appropriate key names and data types (including nested objects). This can be helpful for large resources which are time consuming to write by hand.

Installation

$ go install github.com/jar-b/req2schema@latest

Usage

Usage: req2schema [flags] [filename]

Flags:
  -out string
        output file (optional, prints to stdout if omitted)

Examples

The following is an example of the AWS request schema syntax:

{
   "thing": "string",
   "second": number,
   "another": boolean,
   "nested": [
      {
         "value": "string"
      }
   ]
}

req2schema will infer data types from the field values and generate go source code with a terraform resource schema definition:

$ req2schema testdata/simple.json

package someservice

import (
        "github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
        tftags "github.com/hashicorp/terraform-provider-aws/internal/tags"
)

func ResourceSomeThing() *schema.Resource {
        return &schema.Resource{
                Schema: map[string]*schema.Schema{
                        "another": {
                                Type: schema.TypeBool,
                        },
                        "nested": {
                                Type: schema.TypeList,
                                Elems: &schema.Resource{
                                        Schema: map[string]*schema.Schema{
                                                "value": {
                                                        Type: schema.TypeString,
                                                },
                                        },
                                },
                        },
                        "second": {
                                Type: schema.TypeFloat,
                        },
                        "thing": {
                                Type: schema.TypeString,
                        },
                        "tags":     tftags.TagsSchema(),
                        "tags_all": tftags.TagsSchemaComputed(),
                },
        }
}

The testdata subfolder contains additional requests directly from the AWS documentation.

Additional Considerations

• The resulting source code will be framed out, but incomplete.
  • All items will need one of Required, Optional, or Computed set (this cannot be inferred from the HTTP request schema alone).
  • enum types will need validation added.
  • If unable to determine the type from the incoming request, a TODO comment is added after the type definition as a reminder to determine the appropriate type.
• Not all AWS services include JSON request schemas in the documentation. Some services use XML examples, which this tool does not support.