Free TF-Associate-004 flashcards

Why can a list not be used directly with for_each, and what conversion makes it work?

for_each keys each instance by a stable string, which a map or a set of strings provides but a list does not. Converting the list to set(string) supplies acceptable keys and lets the iteration proceed.

Changing a variable to tuple([string, string]) satisfies for_each, because a fixed-length tuple is the collection it expects.

A tuple looks like an ordered pair that might suit two zones, but for_each rejects tuples just as it rejects lists; it needs a map or a set.

Why does a plain 'terraform apply' pause after printing the proposed plan?

By default apply computes a plan, displays it, and blocks on an interactive confirmation. Only after the operator types 'yes' does it call the providers to create, update, or destroy real resources.

Because apply already generated its own plan during the same command, it applies the changes immediately.

Apply does generate its own plan, but without a saved plan file or -auto-approve it still stops and asks for confirmation first.

If a resource type is declared but no required_providers entry exists, how does terraform init handle the provider?

A resource type such as aws_s3_bucket carries the provider local name as its prefix. Terraform resolves that to the default hashicorp/aws source address and installs the plugin during init, which is the phase responsible for provider installation.

Every provider must be pinned in a required_providers block before any plugin can be installed.

Pinning in required_providers is best practice for version control, but its absence does not stop init. Terraform can still infer and install the provider, so requiring the pin overstates the rule.

When a module's source is a relative path like ./ or ../, how does init retrieve it?

A source prefixed with ./ or ../ denotes a local module, so init resolves it against the working directory on disk and reads the files in place, never contacting the registry or a remote host.

A module block pointing at a subdirectory makes init query the public registry and download the newest matching version.

Registry retrieval is tempting because init does fetch registry modules, but a registry source must be a namespaced address such as 'namespace/name/provider', not a relative path.