Terraform: Variables of type map are requiring defaults when they shouldn't

[abevoelker]

When I put this in variables.tf:

variable "foo" {
    type = "map"
}

and this in terraform.tfvars:

foo.bar = "baz"

Executing terraform plan errors out:

Errors:

  * 1 error(s) occurred:

* Required variable not set: foo

I can fix the error by adding a default value to my variable declaration:

variable "foo" {
    type = "map"
    default = {
        bar = "blah"
    }
}

Then an output declaration is displaying foo = baz in the plan/refresh execution as expected:

output "foo" {
    value = "${var.foo.bar}"
}

However, the documentation leads me to believe that a default value shouldn't be required. In the "VARIABLE CONFIGURATION" section of the documentation, it says this behind the "type" parameter:

this allows variables of type map to be set in the terraform.tfvars file without requiring a default value to be set.

then below that, it says

Default values can be either strings or maps, and if specified must match the declared type of the variable. If no value is supplied for a variable of type map, the values must be supplied in a terraform.tfvars file - they cannot be input via the console.

This issue makes it unusable for my intended use case, which is defining an "environment" variable map which I would define different environment variable keys/values (so staging and production would have different maps). There could be different map keys between environments, so I can't predefine them in a "default" block.

This is happening on Terraform v0.6.11.

[daveadams]

I just ran into this myself. I'm glad to hear there's a workaround.

[phinze]

Noting you should also be able to work around this w/ an empty map:

variable "foo" {
  type    = "map"
  default = {}
}

Paging @jen20 who was in this area of the code recently.

[Lifto]

using
variable "foo" {
type = "map"
default = {}
}
gives this kind of error:

Error running plan: 1 error(s) occurred:

• 1:3: unknown variable accessed: var.foo.bar in:

${var.foo.bar}

[bfgoodrich]

I am seeing this same issue, should be able to pull default for tfvars file or environment variable.

[mitchellh]

With the new 0.7 map features, this is sort of flipped on its head but works now.

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