A quoted type name
Correct in 0.11 and an error since 0.12
variable "region" {
type = "string"
}Terraform Deprecated Syntax Checker
Find the syntax that changed in 0.12, 0.13 and since. Some of it still works and will not forever; some of it a current Terraform refuses outright, with an error that does not mention the rename.
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Examples
Real input you can load into the tool above. Each one shows a different thing going wrong, because that is what the tool is for.
The template_file data source
The provider has no Apple Silicon build, so init fails on a recent Mac
data "template_file" "init" {
template = file("init.sh")
}An interpolation-only string
Still works, and converts the result to a string on the way through
bucket = "${var.bucket_name}"Common mistakes
These are the ones that fail silently. The config is accepted, nothing raises an error, and the consequence arrives later.
Treating an unknown function error as a provider problem
list() and map() were removed in 0.12, and the error names an unknown function. People go looking for a provider that supplies it.
Instead:Use the literal syntax: ["a", "b"] and { a = "b" }.
Wrapping every expression in quotes and ${ }
It works and it converts the result to a string, so a number or a list becomes text and the type error appears far from the cause.
Instead:Write the expression bare: region = var.region.
Keeping template_file because it still works
The template provider has no darwin_arm64 build, so the configuration cannot init at all on a recent Mac. The failure arrives with a new laptop, not with a change to the code.
Instead:Use the built-in templatefile(path, vars) function. No provider needed.
The errors for old syntax rarely mention what replaced it
That is what makes this category expensive: the message describes the symptom accurately and says nothing about the version the syntax came from.
A quoted primitive type is an error now
type = "string" was correct in 0.11. From 0.12 the type is a keyword, and the quoted form has been rejected for several majors. It survives in modules nobody has needed to touch, and the fix is to remove the quotes and, for a collection, say what it holds: list(string).
list() and map() were removed in 0.12
They are still all over copied snippets. The error names an unknown function, which reads like a missing provider rather than a removed builtin. The literal forms are ["a", "b"] and { a = "b" }.
An interpolation-only string converts its result
region = "${var.region}" still works, and it turns whatever the expression produced into a string. A number or a list silently becomes text and the type error appears somewhere else entirely. Write the expression bare.
template_file cannot init on Apple Silicon
The template provider is deprecated and has no darwin_arm64 build, so a configuration using it fails at init on any recent Mac. That is usually how a team discovers the deprecation. The built-in templatefile(path, vars) function needs no provider at all.
version inside a provider block is ignored when required_providers exists
Deprecated since 0.13, and still accepted. When both are present the required_providers entry wins, so the line you are reading is not necessarily the one in force, and the two can disagree indefinitely.
null_resource has a built-in replacement
terraform_data arrived in 1.4 and does the same job with no provider to download, lock or hash. null_resource still works; it is one more thing in your lock file for no benefit.
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