/terraform-provider-fake

I created this fake provider just to test a Terraform bug

Primary LanguageGo

Fake provider

This almost empty provider has been created to test a Terraform bug.

Build and try

go build
terraform init
terrafom plan

Empty string bug?

It seems that default value (or Default or DefaultFunc) is applied for string fields (at least) when we provide an empty string but only when there's no existing state.

With the following main.tf file:

resource "fake" "test" {
  value = ""
}

Starting from scratch (with no state):

$ terraform plan
Terraform will perform the following actions:

  # fake.test will be created
  + resource "fake" "test" {
      + id = (known after apply)
    }

Plan: 1 to add, 0 to change, 0 to destroy.

$ terraform apply -auto-approve
[...]

$ terraform state show fake.test
# fake.test:
resource "fake" "test" {
    id    = "toto"
    value = "plop"
}

Updating main.tf with:

resource "fake" "test" {
  value = "tmp"
}

Then:

$ terraform plan
Terraform will perform the following actions:

  # fake.test will be updated in-place
  ~ resource "fake" "test" {
        id    = "toto"
      ~ value = "plop" -> "tmp"
    }

Plan: 0 to add, 1 to change, 0 to destroy.


$ terraform apply -auto-approve
[...]

$ terraform state show fake.test
# fake.test:
resource "fake" "test" {
    id    = "toto"
    value = "tmp"
}

Reverting main.tf to:

resource "fake" "test" {
  value = ""
}

Then:

$ terraform plan
Terraform will perform the following actions:

  # fake.test will be updated in-place
  ~ resource "fake" "test" {
        id    = "toto"
      - value = "tmp" -> null
    }

Plan: 0 to add, 1 to change, 0 to destroy.


$ terraform apply -auto-approve
[...]

$ terraform state show fake.test
# fake.test:
resource "fake" "test" {
    id    = "toto"
}

With null value it seems to work as expected

resource "fake" "test" {
  value = null
}
$ terraform plan
Terraform will perform the following actions:

  # fake.test will be created
  + resource "fake" "test" {
      + id    = (known after apply)
      + value = "plop"
    }

Plan: 1 to add, 0 to change, 0 to destroy.

$ terraform apply -auto-approve
[...]

$ terraform state show fake.test
# fake.test:
resource "fake" "test" {
    id    = "toto"
    value = "plop"
}
resource "fake" "test" {
  value = "tmp"
}
$ terraform plan
Terraform will perform the following actions:

  # fake.test will be updated in-place
  ~ resource "fake" "test" {
        id    = "toto"
      ~ value = "plop" -> "tmp"
    }

Plan: 0 to add, 1 to change, 0 to destroy.

$ terraform apply -auto-approve
[...]

$ terraform state show fake.test
# fake.test:
resource "fake" "test" {
    id    = "toto"
    value = "tmp"
}
resource "fake" "test" {
  value = null
}
$ terraform plan
Terraform will perform the following actions:

  # fake.test will be updated in-place
  ~ resource "fake" "test" {
        id    = "toto"
      ~ value = "tmp" -> "plop"
    }

Plan: 0 to add, 1 to change, 0 to destroy.

$ terraform apply -auto-approve
[...]

$ terraform state show fake.test
# fake.test:
resource "fake" "test" {
    id    = "toto"
    value = "plop"
}

In Terraform 0.11, default values are not applied for empty string

resource "fake" "test" {
  value = ""
}

$ terraform011 apply -auto-approve
[...]
$ terraform011 state show fake.test
id    = toto