Arbitrary Expressions with Argument Syntax doesn't work

Terraform
1

According to the documentation for Arbitrary Expressions with Argument Syntax we should be able to specify blocks like this

# Not recommended, but valid: a constant list-of-objects expression
example = [
  {
    foo = "bar"
  },
  {
    foo = "baz"
  },
]

But this does not seem to work giving error for resource snowflake_warehouse

An argument named “tag” is not expected here. Did you mean to define a block of type “tag”?

resource "snowflake_warehouse" "foo" {
  name = "foo"

  tag = [
    {
      name = "foor"
      value = "bar"
    },
    {
      name = "env"
      value = "dev"
    },
  ]
}

Specifying as blocks works but I am unsure how to do so dynamically (using dynamic block doesn’t seem to work as it only specifies tag block once)

resource "snowflake_warehouse" "foo" {
  name = "foo"

  tag {
    name = "foor"
    value = "bar"
  }

  tag {
    name = "env"
    value = "dev"
  }
}

Any help is appreciated

2

The error is because there is no attribute called “tag”, as in this case it is a block. For static setups you just repeat the block as many times as you need (assuming the resource supports that) or for dynamic cases you use the dynamic block method.

3

Dynamic blocks work

locals {
  tags = [
    {
      name = "foo"
      value = "bar"
    },
    {
      name = "env"
      value = "dev"
    },
  ]
}

resource "snowflake_warehouse" "foo" {
  name = "foo"

  dynamic tag {
    for_each = local.tags

    content {
      name = tag.value.name
      value = tag.value.value
    }
  } 
}

I am still not sure why the documentation says we can assign though

4

That particular documentation page does say:

Rarely, some resource types also support an argument with the same name as a nested block type

and

The information on this page only applies to certain special arguments that were relying on this usage pattern prior to Terraform v0.12.

5

It depends on the resource. Some accepts a list/map attribute, others expect blocks.