Terraform Professional flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

for expression

A Terraform expression that builds a list or map by iterating a collection; an optional if clause filters elements, and grouping mode builds maps of lists.

dynamic block

Generates repeated nested blocks from a collection using for_each; the iterator argument renames the temporary variable and content defines the block body.

variable validation block

Adds condition and error_message to an input variable; condition must be a bool expression and can reference only that variable in current Terraform versions.

create_before_destroy

A lifecycle setting that creates the replacement resource before destroying the existing object, useful when zero-downtime replacement or unique names require it.

moved block

Declares that a resource or module changed address, so Terraform treats the old address as the same object instead of planning destroy and create.

try function

Returns the first argument that evaluates without error; commonly used for safe attribute access when a value may be null or missing.

state locking

A backend feature that prevents concurrent operations from corrupting state; supported by backends such as S3 with DynamoDB or lockfile, and HCP Terraform.

terraform state mv

Moves a resource or module address within state without changing infrastructure; used to match refactored configuration or reorganize modules.

import block

Configuration block that imports an existing object into state; with -generate-config-out Terraform can generate matching HCL for review.

refresh-only apply

An apply mode that updates state to match remote objects without changing infrastructure; invoked by terraform apply -refresh-only or plan -refresh-only.

terraform_remote_state

Data source that reads outputs from another state file or workspace; it requires backend configuration and exposes only declared outputs, not resource attributes.

module version constraint

The version argument on a registry module source; accepts constraints like ~> 1.2 and selects an installable version during terraform init.

configuration_aliases

A required_providers setting that declares additional provider configurations a module expects; callers pass them through the module's providers map.

module for_each

Meta-argument that instantiates a module once per map or set key; keys must be known at plan time and addresses use module.name["key"].

child module provider blocks

Provider blocks inside reusable child modules are discouraged; modules should declare required_providers and receive configurations from the root module.

registry module address

A source formatted as namespace/name/provider, optionally with hostname; Terraform resolves it through the public or private module registry.

cloud block

A top-level Terraform block that configures HCP Terraform or Terraform Enterprise integration, specifying organization and workspaces for remote runs and state.

VCS-driven run

A run queued automatically when a connected repository changes; HCP Terraform plans and applies in its environment using workspace variables and settings.

run trigger

A workspace setting that queues a run in a dependent workspace after a source workspace applies successfully; used to chain infrastructure layers.

variable set

A reusable collection of Terraform and environment variables applied to workspaces or projects in HCP Terraform; workspace-specific variables can override values.

remote run apply

In HCP Terraform, a run moves through plan, policy check, and apply stages; auto-apply or manual confirmation is controlled by workspace settings.

dependency lock file

The .terraform.lock.hcl file records selected provider versions and checksums; commit it so installs are reproducible across machines and CI.

terraform providers lock

Command that writes lock file entries and checksums for specified platforms, useful when CI runs on a different OS than developers.

pessimistic constraint

The ~> operator allows patch updates within a minor version when two segments are given, or minor updates within a major version with one segment.

provider source address

An address like registry.terraform.io/hashicorp/aws identifying a provider's registry host, namespace, and type in required_providers.

terraform init -upgrade

Re-installs modules and providers while ignoring existing lock file selections where possible, allowing newer versions that satisfy constraints.

sensitive variable

Marks an input variable as sensitive so Terraform redacts it in plan and apply output; the value is still stored in plaintext in state.

ephemeral resource

A Terraform 1.10+ resource whose data is not persisted to state or plan; useful for short-lived credentials and secrets.

terraform test file

A .tftest.hcl file containing run blocks; each run can plan or apply configuration and assert conditions against variables, outputs, or resources.

mock provider in tests

Terraform test feature that supplies fake provider responses for resources and data sources, enabling tests without real cloud credentials.

policy as code

Automated rules evaluated against plan or state data; Terraform Enterprise uses Sentinel, while OPA or Conftest can consume terraform show -json output.

check block

A configuration block that validates conditions during plan and apply and reports warnings without blocking operations; useful for continuous assertions.