terraform-provider-dummy

Introduction

Simple Terraform provider for a tutorial. The provider is a directory, and the provider's resource is a file.

Generally follows Terraform documentation.

Additional References

• Terraform plugin SDK docs
• Terraform plugin SDK source
• Example open source providers
• Posts about writing custom providers. Note that these may be slightly out of date, but the concepts are still applicable.
• Provider for NetBox

Notes

This has all been developed on MacOS. There are not anticipated issues with other OSes.

Steps

• Create initial buildable version of provider
• Add resource to the provider
• Add functioning create and read methods
• Provider can be configured to specify directory
• File name and contents can be specified for a resource
• Unit and acceptance tests added

Step 1

We have a provider that can be built using $ go build -o terraform-provider-dummy

The binary can be invoked but does nothing. $ ./terraform-provider-dummy

Step 2

The provider now includes a resource, but still does nothing.

Step 3

We should now be able to actually use this provider in Terraform and see some results.

$ go build -o terraform-provider-dummy
$ cp terraform-provider-dummy ~/.terraform.d/plugins/darwin_amd64/

The above example is for Mac.

• For Linux use ~/.terraform.d/plugins/linux_amd64/
• For Windows use %APPDATA%\terraform.d\plugins\windows_amd64

Alternatively, we can specify the path to the provider on the command line when doing terraform init.

$ terraform init -plugin-dir=`pwd`
$ terraform validate
$ terraform plan
$ terraform apply

The output of the apply should have the path to the file we created as the ID.

dummy_file.my_file: Creating...
dummy_file.my_file: Creation complete after 0s [id=/var/folders/d9/0fpnfyr91k5_7pl5mqd5sjc80000gn/T/terraform-provider-dummy644603600/step3.txt]

We can verify the contents are as expected.

Step 4

We can configure the provider to use a specific directory.

We have also rearranged the source directory structure for better maintainability.

Try terraform validate, terraform plan, and terraform apply with different values for directory in main.tf. You can try a non-existent directory name or the name of a file to see what happens.

provider dummy {
  directory = "/tmp"
}

Step 5

The file name and contents can be specified as input variables to the resource. Changing contents in main.tf will only modify the existing file. Changing file_name will destroy an existing resource and create a new one.

resource dummy_file my_file {
  file_name = "file.tmp"
  contents  = "initial contents\n"
}

Step 6

Both unit tests and acceptance tests have been added.

All tests will be run via

$ go test -v ./dummy/...

but acceptance tests require TF_ACC environment variable to be set for them to run.

Acceptance tests can be run with

TF_ACC=1 go test -v ./dummy/... -run="TestAcc"

1The provider directory for unit tests is specified through the DUMMY_PROVIDER_DIRECTORY environment variable.

Unresolved Issues

• Versioning
• How to specify the go module for a non-Github repo
• Best way to build and distribute for all platforms