20-Terraform-Exam-Cheat-Sheet

Terraform Certification Exam Cheat Sheet

Terraform

• Cloud-agnostic :

  • Manages infrastructure across different cloud providers
  • Example: AWS, Azure, Google Cloud and on-premises environments.

• Declarative :

  • Uses HashiCorp Configuration Language (HCL) to describe infrastructure's desired state.
  • Specifies resources, configurations, and relationships in code.
  • Terraform determines necessary actions to achieve desired state and executes them.

• Immutable :

  • Treats infrastructure as immutable.
  • Creates new resources or replaces existing ones to match desired state.
  • Does not modify existing resources; creates new version based on updated configuration.
  • Replaces old infrastructure with new one based on updated configuration.

• Idempotence:

  • Ensure that applying the same configuration multiple times has the same result as applying it once, reducing the risk of configuration drift.

• Version Control:

  • Store infrastructure configurations in version control systems (e.g., Git) to track changes, facilitate collaboration, and enable rollbacks.

• Self-describing infrastructure

  • Infrastructure can be described in a way that its purpose, configuration, and dependencies are clear and understandable without needing to inspect the actual infrastructure

• Terraform workflow

  1. Write a Terraform configuration (.tf) file
  2. terraform init : Initializing the Terraform working directory
  3. terraform plan : Planning the infrastructure changes
  4. terraform apply: Applying the changes with terraform apply to create the new infrastructure

• Terraform configuration can be written in

  • HashiCorp Configuration Language (HCL)
  • JSON

• List of All Supported OS

  • macOS
  • Windows
  • Linux
    • Ubuntu/Debian
    • CentOS/RHEL
    • Fedora
    • Amazon Linux
  • FreeBSD
  • OpenBSD
  • Solaris
  • More details : https://developer.hashicorp.com/terraform/install

provider block

• A provider is a plugin that allows Terraform to interact with a specific cloud provider or service
• A provider configuration block is NOT required in every Terraform configuration.
• provider is only required when you are using a specific provider to manage resources
• Providers can be written by individuals
• Providers can be maintained by a community of users
• Some providers are maintained by HashiCorp
• Major cloud vendors and non-cloud vendors can write, maintain, or collaborate on Terraform providers

provisioners

• remote-exec
  • Executes commands on a remote resource over SSH or WinRM after it has been created.
  • This can be used for initial configuration, software installation, or other tasks.
  • example run shell or PS commands on remote EC2
• local-exec
  • Executes commands on the machine running Terraform,
  • Used for tasks that cannot be performed on the remote resource.
  • example run aws cli commands from local machine running terraform
• file
  • Copies files or directories from the machine running Terraform to the newly created resource
  • file provisioner supports ssh and winrm connection types

state file terraform.tfstate

• Name of the state file is terraform.tfstate
• A file that stores the current state of infrastructure managed by Terraform
• "description" argument is NOT stored in the state file, its is used for providing human-readable descriptions
• terraform.tfstate does NOT always matches your currently built infrastructure. Its possible someone has made some manual changes on your infrastructure
• Usernames and passwords referenced in the Terraform code, even as variables, will end up in plain text in the state file
• default location for terraform.tfstate is the current working directory in which Terraform was run

Terraform Commands

• terraform init

• terraform plan

• terraform fmt

• terraform validate

• terraform apply

• terraform apply -replace=aws_instance.{INSTANCE_NAME}

  • recreate the resource during apply (replacement for terraform taint)

• terraform refresh

  • It updates the state file to reflect the current state of the infrastructure
  • It does not process the configuration file

• terraform plan -destroy

• terraform destroy

• terraform get

• terraform state list

• terraform force-unlock

  • use force-unlock only when automatic unlocking fails

remote workspace

• You can have single remote workspace and map multiple configurations( multiple state files)

Terraform Logging

• TF_LOG - Specify the logging level

• TF_LOG_PATH - Specify the path for log file

• TF_LOG available values

  • TRACE : Provides the most detailed logging, this is highest level
  • DEBUG : Provides debug-level logging
  • INFO : Provides informational logging
  • WARN : Provides warning messages
  • ERROR : Provides error messages only

• more details : Terraform-Debug

Terraform workspaces

Terraform modules

• A collection of resources that make up a specific piece of infrastructure
• A group of related resources
• terraform modules are used for
  • Organize configuration
  • Encapsulate configuration
  • Re-use configuration

Terraform sentinel

• policy as code
• can be used to enforce compliance and governance policies before any infrastructure changes are made

Terraform Cloud Free Tier

• Following are available

  • Private Module Registry
  • VCS Connection
  • Single Sign-On (SSO)
  • Remote Terraform execution

• Following are NOT available

  • Team Management
  • Application-level Logging
  • Audit Logging
  • No-code provisioning

• Terraform Version Constraints

  Constraint	Description	Example
  >= 1.0.0 (Greater Than or Equal To)	Allows any version greater than or equal to 1.0.0, such as 1.0.0, 1.0.1, 1.1.0, etc.	>= 1.0.0
  <= 1.0.0 (Less Than or Equal To)	Allows any version less than or equal to 1.0.0, such as 1.0.0, 0.9.9, etc.	<= 1.0.0
  ~> 1.0.0 (Pessimistic Version Constraint)	Allows any version equal to 1.0.0, or greater, but only up to the next significant release, such as 1.0.0, 1.0.1, but not 1.1.0.	~> 1.0.0
  = 1.0.0 (Exact Version)	Allows only the exact version 1.0.0.	= 1.0.0
  != 1.0.0 (Not Equal To)	Excludes version 1.0.0 but allows any other version.	!= 1.0.0

• Terraform Types

  Type	Description	Example
  string	Represents a text string.	"hello", "world"
  number	Represents a numerical value.	5, 10.5
  list	Represents a list of values.	[1, 2, 3], ["a", "b", "c"]
  map	Represents a collection of key-value pairs.	{key1 = "value1", key2 = "value2"}

• Terraform Functions

  Function	Description	Example
  element(list, index)	Returns the element at the specified index in a list.	element([1, 2, 3], 1) returns 2
  format(format_string, arguments)	Formats a string using placeholders and values.	format("Hello, %s!", "world") returns "Hello, world!"
  join(separator, list)	Joins together elements of a list into a single string using a separator.	join(", ", ["a", "b", "c"]) returns "a, b, c"
  lookup(map, key, default)	Looks up a value in a map based on a key, with an optional default value.	lookup({a = "apple", b = "banana"}, "a", "default") returns "apple"

• Structural Types:

  Type	Description	Example
  string	Represents text, such as words or sentences.	"hello", "world"
  number	Represents numerical values, integers or decimals.	5, 10.5
  bool	Represents boolean values, true or false.	true, false
  list	Represents a list of values of the same type.	[1, 2, 3], ["a", "b"]

• Complex Types:

  Type	Description	Example
  map	Represents a collection of key-value pairs, similar to a dictionary.	{key1 = "value1", key2 = "value2"}
  object	Represents a complex structure with multiple attributes, each with its own type.	{name = "John", age = 30, is_active = true}
  tuple	Represents a fixed-size collection of elements, where each element can have a different type.	["apple", 1, true]
  set	Represents a collection of unique elements.	["apple", "banana", "cherry"]

• Terraform Cloud different tiers

  Feature	HCP Free	HCP Standard	HCP Plus	HCP Enterprise
  Infrastructure as code (HCL, CDKTF)	Yes	Yes	Yes	Yes
  Workspaces	Yes	Yes	Yes	Yes
  Variables	Yes	Yes	Yes	Yes
  Runs (separate plan and apply)	Yes	Yes	Yes	Yes
  Providers	Yes	Yes	Yes	Yes
  Modules	Yes	Yes	Yes	Yes
  Public registry	Yes	Yes	Yes	Yes
  Config-driven import	Yes	Yes	Yes	Yes
  Remote state storage	Yes	Yes	Yes	Yes
  VCS connection	Yes	Yes	Yes	Yes
  Projects	Yes	Yes	Yes	Yes
  Secure variable storage	Yes	Yes	Yes	Yes
  Remote runs (plan & apply)	Yes	Yes	Yes	Yes
  Private registry	Yes	Yes	Yes	Yes
  Test-integrated module publishing	5 modules	10 modules	Unlimited	Yes
  Team management	No	Yes	Yes	Yes
  No-code provisioning	No	No	Yes	Yes
  Generated module tests	No	No	Beta	No
  Cross-organization registry sharing	No	No	No	Yes
  Workspace management	Yes	Yes	Yes	Yes
  Workspace explorer	Yes	Yes	Yes	No
  Audit logging	No	No	Yes	Yes
  Drift detection	No	No	Yes	Yes
  Continuous validation	No	No	Yes	Yes
  Ephemeral workspaces	No	No	Yes	Yes
  Runtime metrics (Prometheus)	No	No	No	Yes
  Dynamic provider credentials	Yes	Yes	Yes	Yes
  Policy as code (Sentinel and OPA)	1 Policy set, 5 Policies	1 Policy set, 5 Policies	Unlimited	Yes
  Versioned policy sets	No	No	Yes	Yes
  Policy enforcement level: Advisory	Unlimited	Unlimited	Unlimited	Yes
  Policy enforcement level: mandatory	1 Mandatory	1 Mandatory	Unlimited	Yes
  Run tasks	1 Run task integration, 10 Workspaces attached	1 Run task integration, 10 Workspaces attached	Unlimited	Yes
  Run tasks: advisory enforcement	Unlimited	Unlimited	Unlimited	Yes
  Run tasks: mandatory enforcement	1 Mandatory	1 Mandatory	Unlimited	Yes
  Self-hosted installation	No	No	No	Yes
  Air gap network deployment	No	No	No	Yes
  Application-level logging	No	No	No	Yes
  Log forwarding	No	No	No	Yes
  Audit trails API	No	No	Yes	No
  Single sign-on	Yes	Yes	Yes	Yes
  Support for ServiceNow integrations	No	No	Yes	Yes
  Run triggers	Yes	Yes	Yes	Yes
  Concurrency	1	3	10	Uncapped
  Self-hosted agents	1	1	10	Uncapped
  Active/active scale-out	No	No	No	Yes
  Community	Yes	Yes	Yes	Yes
  Premium support and services	No	Yes	Yes	Yes

Terraform types and functions

Terraform Types

Type	Description	Example
string	Represents a text string.	"hello", "world"
number	Represents a numerical value.	5, 10.5
list	Represents a list of values.	[1, 2, 3], ["a", "b", "c"]
map	Represents a collection of key-value pairs.	{key1 = "value1", key2 = "value2"}

Terraform Functions

Function	Description	Example
element(list, index)	Returns the element at the specified index in a list.	element([1, 2, 3], 1) returns 2
format(format_string, arguments)	Formats a string using placeholders and values.	format("Hello, %s!", "world") returns "Hello, world!"
join(separator, list)	Joins together elements of a list into a single string using a separator.	join(", ", ["a", "b", "c"]) returns "a, b, c"
lookup(map, key, default)	Looks up a value in a map based on a key, with an optional default value.	lookup({a = "apple", b = "banana"}, "a", "default") returns "apple"

Structural Types:

Type	Description	Example
string	Represents text, such as words or sentences.	"hello", "world"
number	Represents numerical values, integers or decimals.	5, 10.5
bool	Represents boolean values, true or false.	true, false
list	Represents a list of values of the same type.	[1, 2, 3], ["a", "b"]

Complex Types:

Type	Description	Example
map	Represents a collection of key-value pairs, similar to a dictionary.	{key1 = "value1", key2 = "value2"}
object	Represents a complex structure with multiple attributes, each with its own type.	{name = "John", age = 30, is_active = true}
tuple	Represents a fixed-size collection of elements, where each element can have a different type.	["apple", 1, true]
set	Represents a collection of unique elements.	["apple", "banana", "cherry"]