Map lookup still throws missing key error when it is never called.

[MaxFlanders]

Terraform Version

Terraform v0.11.7
+ provider.aws v1.14.0
+ provider.null v1.0.0

Terraform Configuration Files

local_variable = ${ contains( keys(var.constants), "some_key" ) == "true" ? var.constants["some_key"] : "other_default_value" }

Expected Behavior

Terraform does not throw a "key does not exist error" unless the key is actually going to be used, especially when the wrapping conditional checks for the existence of the key.

Actual Behavior

An error is thrown:

* module.mod.local.: local.local_variable: key "some_key" does not exist in map var.constants in:
${ contains( keys(var.constants), "some_key" ) == "true" ? var.constants["some_key"] : "other_default_value" }

Steps to Reproduce

Create a conditional local variable like above, which checks the map for a key before using the key, and run terraform.

[jbardin]

Hi @MaxFlanders,

Sorry this is causing you an issue. The index operation does happen in that expression, because conditionals themselves are not short-circuiting.

This is an enhancement we have planned, and there is an open issue at #15605

[ghost]

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