Terraform Questions | PrepOps.Dev

Terraform 101 9 questions

#1
What is Terraform?
#2
What are the advantages in using Terraform or IaC in general?
#3
What is one reason why manual processes can be helpful?
#4
Why is it advisable to avoid using manual processes when creating infrastructure at scale?
#5
What are some of Terraform features?
#6
What language does Terraform uses?
#7
What's a typical Terraform workflow?
#8
What are some use cases for using Terraform?
#9
What's the difference between Terraform and technologies such as Ansible, Puppet, Chef, etc.

Terraform Hands-On Basics 6 questions

#10
Explain the following block of Terraform code
```
resource "aws_instance" "some-instance" {
  ami           = "ami-201720221991yay"
  instance_type = "t2.micro
}
```
#11
What do you do next after writing the following in main.tf file?
```
resource "aws_instance" "some-instance" {
  ami           = "ami-201720221991yay"
  instance_type = "t2.micro
}
```
#12
You've executed terraform init and now you would like to move forward to creating the resources but you have concerns and would like to make be 100% sure on what you are going to execute. What should you be doing?
#13
You've downloaded the providers, seen the what Terraform will do (with terraform plan) and you are ready to actually apply the changes. What should you do next?
#14
Explain the meaning of the following strings that seen at the beginning of each line When you run terraform apply
- '+'
- '-'
- '-/+'
#15
How to cleanup Terraform resources? Why the user should be careful doing so?

Dependencies 3 questions

#16
Sometimes you need to reference some resources in the same or separate .tf file. Why and how it's done?
#17
Does it matter in which order Terraform creates resources?
#18
Is there a way to print/see the dependencies between the different resources?

Providers 11 questions

#19
Explain what is a "provider"
#20
Where can you find publicly available providers?

#21

What are the names of the providers in this case?

terraform {
    required_providers {
      aws = {
        source  = "hashicorp/aws"
      }
      azurerm = {
        source  = "hashicorp/azurerm"
        version = "~> 3.0.2"
      }
    }
  }

#22
How to install a provider?
#23
True or False? Applying the following Terraform configuration will fail since no source or version specific for 'aws' provider
```
terraform {
    required_providers {
      aws = {}
    }
  }
```
#24
Write a configuration of a Terraform provider (any type you would like)
#25
Where Terraform installs providers from by default?
#26
What is the Terraform Registry?
#27
Where providers are downloaded to? (when for example you run terraform init)
#28
Describe in high level what happens behind the scenes when you run terraform init on on the following Terraform configuration
```
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.0"
    }
  }
}
```
#29
True or False? You can install providers only from hashicorp

Variables 22 questions

#30
What are input variables good for in Terraform?
#31
What type of input variables are supported in Terraform?
#32
What's the default input variable type in Terraform?
#33
What ways are there to pass values for input variables?
#34
How to reference a variable?
#35
What is the effect of setting variable as "sensitive"?
#36
True or False? If an expression's result depends on a sensitive variable, it will be treated as sensitive as well
#37
The same variable is defined in the following places:
- The file terraform.tfvars
- Environment variable
- Using -var or -var-file
According to variable precedence, which source will be used first?
#38
Whenever you run terraform apply, it prompts to enter a value for a given variable. How to avoid being prompted?
#39
What are output variables? Why do we need them?
#40
Explain the "sensitive" parameter of output variable
#41
Explain the "depends" parameter of output variable
#42
What are locals?
#43
What's the use case for using locals?
#44
Demonstrate input variable definition with type, description and default parameters
#45
How to define an input variable which is an object with attributes "model" (string), "color" (string), year (number)?
#46
How to reference variables?
#47
How to reference variable from inside of string literal? (bonus question: how that type of expression is called?)
#48
How can list all outputs without applying Terraform changes?
#49
Can you see the output of specific variable without applying terrafom changes?
#50
Demonstrate how to define locals
#51
Demonstrate how to use a local

Data Sources 4 questions

#52
Explain data sources in Terraform
#53
Demonstrate how to use data sources
#54
How to get data out of a data source?
#55
Is there such a thing as combining data sources? What would be the use case?

Lifecycle 3 questions

#56
When you update a resource, how it works?
#57
Is it possible to modify the default lifecycle? How? Why?
#58
You've deployed a virtual machine with Terraform and you would like to pass data to it (or execute some commands). Which concept of Terraform would you use?

Provisioners 11 questions

#59
What are "Provisioners"? What they are used for?
#60
Why is it often recommended to use provisioners as last resort?
#61
What is local-exec and remote-exec in the context of provisioners?
#62
What is a "tainted resource"?
#63
What terraform taint does?
#64
What is a data source? In what scenarios for example would need to use it?
#65
What are output variables and what terraform output does?
#66
Explain "Remote State". When would you use it and how?
#67
Explain "State Locking"
#68
Aside from .tfvars files or CLI arguments, how can you inject dependencies from other modules?
#69
How do you import existing resource using Terraform import?

State 28 questions

#70
Can you name three different things included in the state file?
#71
Why does Terraform keep state and how do local and remote state differ?
#72
Why does it matter where you store the tfstate file? In your answer make sure to address the following:
- Public vs. Private
- Git repository vs. Other locations
#73
True or False? it's common to edit terraform state file directly by hand and even recommended for many different use cases
#74
Why storing state file locally on your computer may be problematic?
#75
Mention some best practices related to tfstate
#76
How and why concurrent edits of the state file should be avoided?
#77
Describe how you manage state file(s) when you have multiple environments (e.g. development, staging and production)
#78
Why storing the state in versioned control repo is not a good idea?
#79
What's a Terraform backend? What is the default backend?
#80
How do you configure an AWS S3 backend with DynamoDB state locking?
#81
Which commands help you inspect, migrate, and safely manipulate Terraform state?
#82
What best practices keep Terraform state secure and reliable?
#83
How do you migrate from local state to a new remote backend?
#84
How terraform apply workflow is different when a remote backend is used?
#85
What would be the process of switching back from remote backend to local?
#86
True or False? it's NOT possible to use variable in a backend configuration
#87
Is there a way to obtain information from a remote backend/state using Terraform?
#88
How does a remote state backend improve collaboration for a Terraform project?
#89
Explain what is a Terraform workspace
#90
True or False? Each workspace has its own state file
#91
Why workspaces might not be the best solution for managing states for different environments? like staging and production
#92
Which command will produce a state file?
#93
How to inspect current state?
#94
How to list resources created with Terraform?
#95
How do you rename an existing resource?
#96
How to create a new workspace?
#97
How to identify which workspace are you using?

Terraform Structures and Syntax 33 questions

#98
How to define an input variable which is a list of numbers?
#99
How to create a number of resources based on the length of a list?
#100
You have a list variable called "users" with an object containing a name attribute like this:
```
variable "users" {
  type = list(object({
    name = string
    age  = number
  }))
}
```
How to access the name attribute of the second item in that list?
#101
Given the same list, how to access attribute "name" of all items?
#102
What loops are useful for in Terraform?
#103
Demonstrate how to define a simple Terraform loop
#104
How to create multiple AWS instances but each with a different name?
#105
You have the following variable defined in Terraform
```
variable "users" {
  type    = list(string)
  default = ["mario", "luigi", "peach"]
}
```
How to use it to create users on one of the public clouds (or any other platform, infra)?
#106
Is there any limitation to "count" meta-argument?
#107
What's a for_each loop? How is it different from "count"?
#108
Demonstrate how to use the for_each loop
#109
The following resource tries to use for_each loop on a list of strings but it fails, why?
```
resource “google_compute_instance” “instances” {

  for_each = var.names
  name = each.value
}
```
#110
How to use for_each loop for inline blocks?
#111
There is a list variable called "users". You would like to define an output variable with a value of all users in uppercase. How to achieve that?

#112

What's the result of the following code?

resource "random_integer" "num" {
  min = 20
  max = 17
}

resource "aws_instance" "instances" {
  count = random_integer.num.results
}

#113
There is a variable called "values" with the following value: ["mario", "luigi", "peach"]. How to create an output variable with the string value of the items in the list: "mario, luigi, peach," ?
#114
There is a list variable called "users". You would like to define an output variable with a value of all users in uppercase but only if the name is longer than 3 characters. How to achieve that?
#115
There is a map called "instances"
- How to extract only the values of that map?
- How to extract only the attribute "name" from each value?
#116
You have a map variable, called "users", with the keys "name" and "age". Define an output list variable with the following "my name is {name} and my age is {age}"
#117
You have a map variable, called "users", with the keys "name" (string) and "age" (number). Define an output map variable with the key being name in uppercase and value being age in the closest whole number
#118
How to use conditional expressions in Terraform?
#119
Explain the following condition: var.x ? 1 : 0
#120
Explain the following condition: var.x != "" ? var.x : "yay"
#121
Can conditionals be used with meta-arguments?
#122
Is it possible to combine conditionals and loop?
#123
What are meta-arguments in Terraform?
#124
What meta-arguments are you familiar with?
#125
What templatefile function does?
#126
You are trying to use templatefile as part of a module and you use a relative path to load a file but sometimes it fails, especially when others try to reuse the module. How can you deal with that?
#127
How do you test terraform syntax?
#128
True or False? Terraform console should be used carefully as it may modify your resources
#129
You need to render a template and get it as string. Which function would you use?
#130
Explain what depends_on used for and given an example

Modules 20 questions

#131
Explain Modules
#132
What makes a Terraform code module? In other words, what a module is from practical perspective?
#133
When should you use a module instead of inline resources?
#134
What is a recommended layout for a reusable module?
#135
How do you consume a versioned module from a VCS or the Terraform Registry?
#136
How do modules handle inputs, outputs, locals and validation effectively?
#137
Which module anti-patterns should you avoid?
#138
How do you test and lint modules during development?
#139
How do you test a Terraform module?
#140
When creating a module, do you prefer to use inline blocks, separate resources or both? why?
#141
True or False? Module source can be only local path
#142
Where can you obtain Terraform modules?
#143
You noticed there are relative paths in some of your modules and you would like to change that. What can you do and why is that a problem in the first place?
#144
How to use a module?
#145
Demonstrate using a module called "amazing_modle" in the path "../modules/amazing-module"
#146
What should be done every time you modify the source parameter of a module?
#147
How to access module output variables?
#148
You would like to load and render a file from module directory. How to do that?
#149
There is a module to create a compute instance. How would you use the module to create three separate instances?
#150
How to use a module with for_each to create networks per availability zone?

Import 2 questions

#151
Explain Terraform's import functionality
#152
State two use cases where you would use terraform import

Version Control 1 question

#153
You have a Git repository with Terraform files but no .gitignore. What would you add to a .gitignore file in Terraform repository?

AWS 5 questions

#154
What happens if you update user_data in the following case and apply the changes?
```
resource "aws_instance" "example" {
 ami = "..."
 instance_type = "t2.micro"

 user_data =  index.xhtml
 EOF
}
```
#155
You manage ASG with Terraform which means you also have "aws_launch_configuration" resources. The problem is that launch configurations are immutable and sometimes you need to change them. This creates a problem where Terraform isn't able to delete ASG because they reference old launch configuration. How to do deal with it?
#156
How to manage multiple regions in AWS provider configuration?
#157
Assuming you have multiple regions configured and you would like to use a module in one of them. How to achieve that?
#158
How to manage multiple AWS accounts?

Validations 1 question

#159
How would you enforce users that use your variables to provide values with certain constraints? For example, a number greater than 1

Secrets 6 questions

#160
What's the issue with the following provider configuration?
```
provider "aws" {
  region = "us-west-1"

  access_key = "blipblopblap"
  secret_key = "bipbopbipbop"
}
```
#161
What can you do to NOT store provider credentials in Terraform configuration files in plain text?
#162
How can you manage secrets/credentials in CI/CD?
#163
What are the pros and cons of using environment variables for managing secrets in Terraform configurations?
#164
True or False? If you pass secrets with environment variables, they are not visible in your state file
#165
True or False? If you pass secrets from a centralized secrets store (like Hashicorp Vault) they are not visible in plan files (terraform plan)

Production 10 questions

#166
What structure layout do you use for your projects?
#167
What files do you have you have in your Terraform projects?
#168
An engineer in your team complains about having to copy-paste quite a lot of code between different folders and files of Terraform. What would you do?
#169
When working with nested layout of many directories, it can make it cumbresome to run terraform commands in many different folders. How to deal with it?
#170
One of the engineers in your team complains the inline shell scripts are quite big and maintaining them in Terraform files seems like a bad idea. What would you do?
#171
You noticed a lot of your Terraform code/configuration is duplicated, between repositories and also within the same repository between different directories. What one way you may adopt that will help handling with that?
#172
You noticed your Terraform code includes quite a lot of hardcoded values (like ports, subnets, ...) and they are duplicated in many locations. How'd you deal with it?
#173
Every time there is a change in tags standards (for example your team decided to change one of the tags' name) you find yourself changing tags in multiple files and you find the process quite tedious. What can be done about it?
#174
You would like to change the name of a resource but afraid to cause downtime. What can be done?
#175
You try to deploy a cluster and an app on that cluster, but the app resource was created before the cluster. How to manage such situation?