Task 4.3: Use variables and outputs

• Aus-east-2, because environment variables take precedence over files

  Incorrect

  Environment variables are near the bottom of the order, above only the default.

• Bus-west-2, since terraform.tfvars outranks environment variables

  Correct

  In the precedence order, terraform.tfvars is above environment variables, which are only above the variable's default.

• CNeither; Terraform stops with an error about two conflicting values

  Incorrect

  Multiple sources are allowed; the precedence order resolves them.

• Dus-east-2, because the variable is read from the shell before any file

  Incorrect

  Load order does not decide; the precedence order does.

Environment variables sit near the bottom of the precedence order, above only the variable's default.

• ATF_VAR_db_name

  Correct

  Terraform reads environment variables named TF_VAR_ followed by the variable name.

• BTERRAFORM_DB_NAME

  Incorrect

  Terraform does not read that naming pattern.

• CTF_CLI_ARGS_db_name

  Incorrect

  TF_CLI_ARGS variables add command-line arguments, not variable values by name.

• DVAR_db_name

  Incorrect

  The prefix is TF_VAR_.

TF_VAR_<name> sets root module variables from the environment.

• ATerraform uses an empty string

  Incorrect

  There is no implicit empty value.

• BTerraform skips every resource that uses the variable and plans the rest

  Incorrect

  Terraform does not skip resources for missing inputs.

• CTerraform prompts for a value

  Correct

  If a variable has no default and no value, Terraform prompts the user to supply one before planning.

• DTerraform reads the last value from state

  Incorrect

  Variables are not read from state.

Required variables are prompted for interactively; automation must supply them.

• AA comment above each block, which Terraform shows in plans

  Incorrect

  Comments are ignored by Terraform.

• BA locals block that repeats each name with an explanation

  Incorrect

  Locals are for expressions, not documentation.

• CA description argument on each variable and output block

  Correct

  Variable and output blocks accept a description that documents their purpose.

• DA sensitive argument on each block

  Incorrect

  sensitive hides values; it documents nothing.

description is the documented place to explain a module's interface.

• APass each list element as a separate -var option

  Incorrect

  Each -var sets a whole variable; repeated options override each other.

• BChange the variable's type to string and split it later

  Incorrect

  Changing types to avoid quoting makes the module harder to use.

• CUse PowerShell, which passes quotes to Terraform unchanged

  Incorrect

  The docs specifically advise against PowerShell for this.

• DPut the value in a .tfvars file and pass it with -var-file

  Correct

  For complex values the docs recommend variable definition files, which Terraform parses directly instead of relying on the shell.

Variable files avoid shell quoting problems entirely.

• AOnly in the cloud provider's web console, next to the load balancer

  Incorrect

  Outputs are a Terraform feature shown by the CLI.

• BAfter apply, and with terraform output

  Correct

  Root module outputs are displayed after apply and can be queried later with terraform output.

• COnly inside child modules

  Incorrect

  This is a root module output, shown by the CLI.

• DOnly in the plan file

  Incorrect

  Outputs are also stored in state and printed after apply.

Root outputs are how a configuration reports results to people and tools.