Creating a custom provider Data Source that takes arguments

Terraform Providers Plugin Development
1

Hello!

New to Terraform/provider creation (using the plugin framework), and I have a very basic question that I hope someone can help me with!

Following the tutorial (which is great, by the way), I’m able to create a very simple data source that takes no parameters. So my main.tf with the following stanza works fine:

data "shepherd_projects" "test" {
}

So my provider (“shepherd”) has a data source called “project”. This works fine.

My problem comes when I want to be able to specify that this data source needs to take some arguments. So my stanza should/must look like:

data "shepherd_projects" "test" {
  department_id = "893eb7c8-6141-4ea5-92cb-5a84c463461f"
  region_id = "cnco1"
}

(My code needs to take that department_id and region_id and use it to call my own shepherd SDK in the data source Read() method)

How do I implement this?
Running “apply” immediately errors out with complaints that the two arguments are “Unsupported argument”

The tutorial doesn’t cover this (only shows how to create a data source with zero arguments) - and reading up on the core documentation for Data Sources - there is a discussion on how to pass provider configuration to the data source - but not how to get config data from the data source stanza itself.

Googling around the internet, I see examples on how to do this using the SDKV2, but I don’t see any for the plugin framework. This seems like a pretty basic functionality that would be useful in many custom providers, so I’m going nuts thinking I’m missing some big picture.

Any help - or pointers to code samples - would be greatly appreciated. Thank you!

2

Start thinking in terms of “attributes” rather than “arguments”.

Your “no arguments” data source should have a bunch of attributes which are marked Computed: true in the schema.

Add some additional attributes to your model struct, and mark them with either Required: true or Optional: true in the schema.

3

Thanks for the reply - while I actually did have attributes defined in my schema - I had nested them incorrectly. Fixing up the schema to allow for proper nesting, I was then able to get the attributes I needed in the Read method and was able to proceed.

So, fixing the schema method was indeed the solution here. Thank you!

4

Cool. Glad you figured it out.

5

can you please share what helped you?
because looks like I’m stuck there.

I don’t see how to read/access passed arguments inside Read method.

Maybe you can show example of how to access them? (I can pass arguments but don’t see how to read them properly)

Thanks.

6

The first things your Read() method should do are:

  • Instantiate a variable of the type which matches your schema (a struct with tfsdk tags)
  • Unpack the configuration supplied by the user onto that struct using req.Config.Get()

Like this.