Terraform

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Theory
Quiz

    Resource Count Dependencies & Graph

    • Can you use count and for_each on module blocks, and how does that change how you call modules?

      Mid

    • How does Terraform determine the order in which resources are created? Explain the difference between implicit and explicit dependencies.

      Mid

    • How does Terraform handle the dependency graph, and what happens if there is a circular dependency?

      Senior

    • How does Terraform's resource graph allow it to perform parallel operations?

      Senior

    • What does the -parallelism flag control, and why might you lower it during an apply?

      Senior

    • What is a dynamic block, and when would you use one instead of simply defining multiple standard resource blocks?

      Mid

    • What is the fundamental difference between using count and for_each to create multiple resources, and which one is safer for resources that might be removed from the middle of a list, and why?

      Mid

    Modules & Composition

    • Explain the concept of 'Module Composition.' How do you pass data from one module to another?

      Senior

    • How do you balance the DRY principle with the need for infrastructure code to be explicit and easy to audit?

      Senior

    • What constitutes a 'Terraform Module,' and what are the benefits of using them in a large-scale project?

      Junior

    • What is the difference between a 'Root Module' and a 'Child Module'?

      Junior

    • What is the flat module versus nested module debate, and why is deep nesting of modules generally discouraged in large-scale environments?

      Senior

    • What is the Terraform Registry, and what is the difference between the public and private versions?

      Junior

    • What makes a good module? Explain the trade-offs between creating highly generic modules versus specialized, small modules.

      Mid

    • Why is it critical to pin module versions in a production environment, and what are the pros and cons of using a Git URL versus a Terraform Registry source?

      Mid

    Drift Import & Refresh

    • Explain the concept of infrastructure drift. How does Terraform detect it, and what are the strategies for reconciling it?

      Mid

    • Explain the difference between terraform plan -refresh-only and a standard terraform plan.

      Senior

    • How do you handle importing existing infrastructure into Terraform, and what are the limitations of terraform import vs the new import blocks?

      Senior

    • What is the difference between terraform refresh and the newer terraform plan -refresh-only, and when would you use the latter?

      Mid

    • When should you use a data source to fetch information about an existing resource versus using the terraform_remote_state data source?

      Mid

    • When would you use terraform import, and what are its limitations regarding the configuration file?

      Mid

    Validation Policy & Targeted Operations

    • Explain the concept of Policy as Code (Sentinel or OPA) within the Terraform workflow. At what stage of the plan/apply cycle are these policies enforced?

      Senior

    • Explain the purpose of the check block. How does it differ from a standard resource validation or a precondition?

      Senior

    • How do precondition and postcondition blocks work, and how do they differ from variable validation?

      Senior

    • What is a variable validation block, and how do you use it to enforce constraints on input variables?

      Mid

    • When should you use terraform destroy, and how can you target a specific resource for destruction without affecting the whole stack?

      Mid

    • When would you use the -target flag, and what are the primary risks of using it in a production environment?

      Mid

    Remote Operations & Collaboration

    • Explain the concept of Terraform workspaces. How do they differ from using a separate directory structure for different environments?

      Mid

    • How does a VCS-driven workflow work in Terraform Cloud, and how does it differ from CLI-driven runs?

      Senior

    • What does the terraform login command do, and how does it relate to authenticating with Terraform Cloud?

      Junior

    • What is the difference between a local execution and a remote execution in Terraform Cloud, and how does this affect secrets management?

      Senior

    Core Concepts & Philosophy

    • Explain the difference between a declarative tool like Terraform and an imperative tool like Ansible or shell scripts.

      Junior

    • Explain the difference between the 'Desired State' and the 'Current State' in the context of a Terraform run.

      Junior

    • From a software engineer's perspective, what are the trade-offs of using HCL (Terraform) versus a real programming language like TypeScript or Python (Pulumi/AWS CDK)?

      Senior

    • How does Terraform's provider plugin architecture work, and how does it let Terraform remain provider-agnostic?

      Mid

    • What are the trade-offs of using a 'Cloud-Agnostic' tool like Terraform versus a 'Cloud-Native' tool like AWS CloudFormation or Azure Bicep?

      Senior

    • What is the Terraform state file, and why is it considered the source of truth even if the cloud provider has its own API?

      Junior

    Variables Outputs & Locals

    • Explain the difference between output values and variable inputs.

      Junior

    • How do you handle sensitive data like passwords or API keys that ends up in the plain-text state file?

      Mid

    • How does Terraform determine variable precedence if a value is defined in a .tfvars file, an environment variable, and a default value?

      Mid

    • What does marking a variable or output as 'sensitive' actually do, and what are its limitations?

      Mid

    • What is the conceptual difference between an input variable and a local value, and when is it a best practice to use a local?

      Junior

    • What is the purpose of the terraform output command, and how do you consume outputs programmatically?

      Junior

    State Management & Backends

    • Explain the process of migrating state from a local backend to a remote backend such as S3 or Terraform Cloud.

      Mid

    • How does the terraform_remote_state data source work, and what are the security considerations of exposing another state's outputs?

      Senior

    • If you inherited a monolith Terraform state file with thousands of resources in one state, what is your conceptual strategy for breaking it into smaller, isolated states?

      Senior

    • What do terraform state list and terraform state show do, and when would you reach for them?

      Junior

    • What happens if the state file is accidentally deleted? How would you attempt to recover or rebuild it?

      Senior

    • What happens to the state file and the infrastructure if your network connection drops or the CLI process is killed in the middle of a terraform apply, and how does state locking protect against this?

      Senior

    • What is a 'Remote Backend,' and what are the advantages of using one like S3 or Terraform Cloud over a local backend?

      Junior

    • What is partial backend configuration, and why would you supply backend settings at init time rather than hard-coding them?

      Senior

    • What is state locking, and why is it required in a team environment? Which backends support it, and what happens if a lock is not released?

      Mid

    • What is the difference between terraform state mv and terraform state rm? When would you use each?

      Mid

    • What is the difference between terraform state pull and terraform state push, and why are they risky?

      Senior

    • What is the difference between terraform state rm and terraform destroy?

      Mid

    Settings Providers & Versioning

    • Explain the purpose of the .terraform.lock.hcl file and why it should be committed to version control.

      Mid

    • How can you keep provider credentials out of your configuration, and what are the common ways Terraform authenticates to a cloud provider?

      Mid

    • How do provider version constraints work, and what does an operator like ~> mean in a version constraint?

      Mid

    • How do you manage multiple instances of the same provider (e.g., deploying to two different AWS regions) using 'Aliases'?

      Mid

    • What is the purpose of the terraform {} settings block, and what do required_version and required_providers control?

      Junior

    • What is the terraform replace-provider command used for, and when would you need it?

      Senior

    Workflow & Cli Lifecycle

    • Explain the Terraform lifecycle (Init, Plan, Apply, Destroy). What happens under the hood during each step?

      Mid

    • In a CI/CD pipeline, why is it important to run terraform plan and terraform apply in separate stages with a manual approval step?

      Mid

    • What does a terraform plan actually represent, and does a successful plan guarantee a successful apply: why or why not?

      Mid

    • What does the terraform console command do, and how is it useful during development?

      Junior

    • What does the terraform graph command produce, and how can it help you understand your configuration?

      Mid

    • What exactly happens during terraform init, and if you add a new provider to your configuration why do you have to run init again?

      Junior

    • What is the difference between terraform apply and terraform apply with a planfile?

      Mid

    • What is the difference between terraform plan and terraform apply, and why is it a best practice to save a plan file?

      Junior

    • What is the difference between terraform validate and terraform fmt?

      Junior

    • What is the risk of using -auto-approve, and in what contexts is it acceptable?

      Junior

    Resources Data Sources & Provisioners

    • Explain the terraform_data resource (formerly null_resource). When would you use it?

      Mid

    • What are data sources, and how do they allow Terraform to interact with infrastructure it does not manage?

      Junior

    • What does the templatefile function do, and when would you use it instead of inline strings or heredocs?

      Mid

    • What is the difference between a creation-time and a destroy-time provisioner?

      Mid

    • What is the difference between a provider and a provisioner, and why are provisioners like local-exec considered a last resort?

      Mid

    • What is the difference between a resource block and a data source block?

      Junior

    • Why are provisioners like local-exec and remote-exec considered a last resort in Terraform? What are the recommended alternatives?

      Mid

    Lifecycle & Resource Management

    • Explain the use cases for create_before_destroy, prevent_destroy, and ignore_changes. How does create_before_destroy help with zero-downtime updates?

      Mid

    • How do you rename a resource or move it into a module without Terraform attempting to destroy and recreate it, and why is a moved block preferred over terraform state mv?

      Mid

    • What is the difference between the deprecated terraform taint command and the -replace flag in terraform apply?

      Mid

    • What is the replace_triggered_by argument in the lifecycle block, and what scenario does it address?

      Senior

    Hcl Expressions & Types

    • How does the ternary conditional expression work in HCL, and when would you use it?

      Junior

    • How does type conversion work in Terraform, and what functions help convert between types?

      Mid

    • What are for-expressions in HCL, and how do you use them to transform a list or map into another collection?

      Mid

    • What are the different type constraints in Terraform (string, number, bool, list, map, set, object, tuple), and why do complex types matter?

      Mid

    • What are the major categories of Terraform's built-in functions, and can you give examples of when you'd use string, collection, or numeric functions?

      Junior

    • What do the try() and can() functions do, and when are they useful for handling dynamic or uncertain values?

      Senior

    • What is a heredoc in HCL, and when would you use one over normal string interpolation?

      Junior

    • What is a splat expression in Terraform, and what problem does it solve when working with lists of resources?

      Mid

    • What is the optional() modifier in object type definitions, and how does it help with variable defaults?

      Senior