File functions (file, templatefile) in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Terraform file() function do?

The file() function reads the contents of a file from the local filesystem and returns it as a string. It's useful for including file content directly in Terraform configurations.

beginner

How does templatefile() differ from file() in Terraform?

templatefile() reads a file and processes it as a template, replacing placeholders with provided variables. file() just reads the file content as-is without substitutions.

intermediate

What is the correct way to pass variables to templatefile()?

You pass a map of variable names and values as the second argument to templatefile(). The template file uses ${varname} syntax to insert these values.

beginner

Give an example use case for file() in Terraform.

Use file() to read a script file (like a shell script) and pass its content to a resource's user_data field to run on a virtual machine at startup.

intermediate

What happens if the file path given to file() or templatefile() does not exist?

Terraform will return an error and stop the plan or apply process because it cannot read the required file.

What does the Terraform file() function return?

A A map of variables

B The file content as a string

C A list of file names

D A boolean indicating file existence

file() reads the entire file content and returns it as a string.

Which function allows variable substitution inside a file's content?

A templatefile()

B file()

C jsondecode()

D join()

templatefile() processes templates and replaces placeholders with variables.

How do you provide variables to templatefile()?

A As a map of key-value pairs

B No variables can be passed

C As a single string

D As a list of strings

Variables are passed as a map to templatefile() for substitution.

What syntax is used inside a template file for variable placeholders?

A #varname#

B <varname>

C {{varname}}

D ${varname}

Terraform templates use ${varname} syntax for variables.

What happens if the file path in file() is incorrect?

A Terraform ignores the error

B Terraform creates an empty file

C Terraform returns an error and stops

D Terraform retries reading the file

Terraform fails with an error if the file cannot be found or read.

Explain how file() and templatefile() functions work in Terraform and when to use each.

Think about reading plain files versus files with placeholders.

Describe the process of passing variables to a template file in Terraform and how they are used inside the template.

Focus on the map argument and placeholder syntax.