Top 50 Pulumi Interview Question and Answers

15 Oct 2024 - Shyam Mohan

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1. What is Pulumi?
   • Pulumi is an open-source infrastructure-as-code (IaC) tool that allows developers to define cloud resources and infrastructure using programming languages like TypeScript, JavaScript, Python, Go, and .NET.
2. What are the benefits of using Pulumi over other IaC tools?
   • Pulumi allows you to use general-purpose languages, integrates with modern CI/CD, has multi-cloud support, and supports cloud-native technologies like Kubernetes.
3. What programming languages does Pulumi support?
   • Pulumi supports TypeScript, JavaScript, Python, Go, and C#.
4. How does Pulumi handle state management?
   • Pulumi can manage state in the Pulumi Cloud or in a self-hosted backend like AWS S3, Google Cloud Storage, or an on-premise file system.
5. What is the Pulumi CLI used for?
   • The Pulumi CLI is used to create, update, and destroy infrastructure, manage state, configure stacks, and interact with cloud providers.
6. What is a stack in Pulumi?
   • A stack is an isolated instance of Pulumi’s cloud infrastructure, typically representing a particular environment, such as development, staging, or production.
7. How do you manage stack configurations?
   • Stack configurations in Pulumi can be managed using the pulumi config command or directly in Pulumi.<stack-name>.yaml files.
8. Can you explain how Pulumi’s state is stored?
   • Pulumi’s state is stored as a JSON document containing information about each resource managed by Pulumi. This state is saved either in the Pulumi Cloud, a custom backend, or locally.
9. How does Pulumi handle secrets and sensitive data in configurations?
   • Pulumi supports secret configuration using pulumi config set --secret to encrypt sensitive data, which is encrypted in the state file and only decrypted during runtime.
10. How do you manage stack secrets in Pulumi?
    • Pulumi uses a passphrase or cloud-based encryption services (e.g., AWS KMS, Azure Key Vault) to encrypt and manage stack secrets.
11. What are Pulumi resource components?
    • Resource components are reusable abstractions built from underlying resources, allowing developers to group and manage resources together in a modular way.
12. What are the core classes in Pulumi?
    • Core classes include pulumi.ComponentResource, pulumi.CustomResource, and resource providers specific to cloud resources.
13. How does Pulumi’s support for languages benefit infrastructure-as-code?
    • With general-purpose languages, Pulumi allows for complex logic, conditions, loops, and functions that aren’t possible in traditional IaC DSLs like HCL or YAML.
14. What is the purpose of the ComponentResource class?
    • ComponentResource is used to define custom, reusable components, grouping multiple resources into a single, logical resource.
15. How can you test Pulumi code?
    • Pulumi code can be tested using unit tests (e.g., with pytest for Python or mocha for JavaScript) and integration tests by mocking resource providers.
16. What are Pulumi providers?
    • Providers are plugins that Pulumi uses to interact with specific cloud platforms or services, such as AWS, Azure, GCP, and Kubernetes.
17. How does Pulumi support multi-cloud environments?
    • Pulumi allows defining resources from different providers in the same stack, enabling the management of multiple cloud platforms within a single project.
18. What is a CustomResource in Pulumi?
    • CustomResource represents a cloud resource that can be created, updated, or deleted by Pulumi. It’s the base type for defining cloud resources.
19. Can Pulumi deploy Kubernetes resources?
    • Yes, Pulumi has first-class support for Kubernetes, allowing developers to define, deploy, and manage Kubernetes resources in their preferred programming language.
20. How do you configure multiple providers in a single Pulumi project?
    • By creating provider instances with different configurations, multiple providers can be used within the same Pulumi project.
21. How do you create a new Pulumi project?
    • Run pulumi new <template> to create a new project. Pulumi offers templates for different languages and cloud providers.
22. What are Pulumi templates?
    • Templates are predefined project configurations for different languages and providers, serving as starter templates for Pulumi projects.
23. How can you import existing cloud resources into Pulumi?
    • Pulumi provides an import option using the pulumi import command, which allows users to bring existing resources under Pulumi management.
24. What does pulumi up do?
    • pulumi up previews and applies changes to the stack, creating, updating, or deleting resources as defined in the code.
25. What does pulumi destroy do?
    • pulumi destroy removes all resources in the stack, effectively tearing down the infrastructure.
26. What is a dynamic provider in Pulumi?
    • Dynamic providers enable you to create custom resources with unique lifecycle management and logic, typically implemented in a programming language rather than relying on a provider.
27. How does Pulumi handle drift detection?
    • Pulumi compares the state file with the actual infrastructure configuration and alerts users about detected drift during preview or update commands.
28. What are resource options in Pulumi?
    • Resource options, like dependsOn, protect, and ignoreChanges, allow you to control resource behaviors and dependencies.
29. What is the use of dependsOn in Pulumi?
    • dependsOn specifies explicit dependencies between resources, ensuring they are created or modified in the correct order.
30. What are Pulumi plugins, and how are they managed?
    • Pulumi plugins extend the functionality of the Pulumi CLI, allowing it to interact with various providers. Plugins are managed automatically but can also be manually installed using pulumi plugin install.
31. How do you debug issues in Pulumi deployments?
    • Use pulumi up --debug for detailed logging and review stack outputs, configurations, and dependencies to troubleshoot issues.
32. What is the Pulumi preview mode, and how is it useful?
    • Preview mode (pulumi preview) simulates changes without applying them, allowing users to validate and review changes before deployment.
33. What common issues can occur with Pulumi state files, and how do you resolve them?
    • Corrupted or inconsistent state files may lead to deployment errors, resolvable by refreshing state (pulumi refresh) or fixing the state file manually if needed.
34. How do you update or upgrade Pulumi’s CLI or plugins?
    • Update the CLI with brew upgrade pulumi (if using Homebrew) and plugins with pulumi plugin upgrade.
35. What is the purpose of ignoreChanges?
    • ignoreChanges tells Pulumi to skip updates on specified properties of a resource, which is useful for settings managed outside of Pulumi.
36. How can Pulumi be integrated into CI/CD pipelines?
    • Pulumi can be integrated into CI/CD pipelines using the CLI commands in workflows such as GitHub Actions, GitLab CI, or Jenkins.
37. What are Pulumi GitHub Actions?
    • Pulumi GitHub Actions are reusable workflows to automate Pulumi deployments directly from GitHub repositories.
38. How does Pulumi handle rollbacks?
    • Pulumi does not have an automatic rollback feature, but you can re-deploy previous configurations to restore infrastructure to a desired state.
39. What is the Pulumi Automation API?
    • The Automation API is a way to programmatically interact with Pulumi, allowing you to create, update, or destroy infrastructure as part of custom applications or scripts.
40. What is Policy as Code (PaC) in Pulumi?
    • Policy as Code in Pulumi enforces rules and policies for infrastructure configurations, ensuring compliance and security best practices.
41. How do you handle version control for Pulumi projects?
    • Pulumi projects can be managed in Git or other version control systems. This includes storing the Pulumi code, configuration files (Pulumi.<stack>.yaml), and state (if not stored in the Pulumi Cloud or a remote backend). It’s also beneficial to use Git branches to separate changes for different environments or stacks.
42. What is the role of the protect option in resource management?
    • The protect option in Pulumi ensures that a resource cannot be deleted or replaced accidentally. When protect is enabled on a resource, it requires an explicit command to override the protection during deletion or replacement, adding an extra layer of safety for critical infrastructure.
43. Can you explain how pulumi refresh works?
    • pulumi refresh synchronizes Pulumi’s state with the real-world state of your infrastructure. This command detects drift (changes made outside of Pulumi) and updates the Pulumi state to reflect these changes, ensuring Pulumi’s internal state is consistent with actual resources.
44. What is the retention policy in Pulumi, and how do you set it up?
    • Pulumi allows specifying a retention policy for resources, especially useful in Kubernetes. For instance, by setting a retain policy, Pulumi ensures that a resource is not deleted when it’s removed from the code. It’s applied by specifying the pulumi.ResourceOptions.retention flag on a resource.
45. How do you share and collaborate on Pulumi projects?
    • Pulumi projects can be shared and collaborated on by using version control and sharing access to the Pulumi state backend. In team settings, the Pulumi Cloud or a shared backend (e.g., S3 or GCS) ensures everyone has access to the latest stack states and can work on infrastructure changes collaboratively.
46. How would you deploy multi-region infrastructure with Pulumi?
    • Multi-region deployments can be achieved by configuring different providers within Pulumi for each region. By setting the region property on cloud provider configurations, you can create resources in multiple regions, often managed in separate stacks or grouped logically within a single stack.
47. What is the purpose of the additionalSecretOutputs setting?
    • additionalSecretOutputs is used in Pulumi to automatically mark specific resource outputs as secrets, even if they aren’t natively marked as sensitive. This setting ensures sensitive information in outputs (like keys or tokens) is encrypted and only decrypted at runtime.
48. How do you handle large Pulumi projects?
    • Large Pulumi projects can be managed by breaking them into reusable components using ComponentResource. Components allow complex infrastructure to be modular, enabling easier testing, reuse, and maintenance. Additionally, using multiple stacks and defining dependencies carefully improves project scalability.
49. What are the common security considerations in Pulumi?
    • Key security considerations include encrypting secrets in the configuration, setting up role-based access control, using additionalSecretOutputs for sensitive outputs, and auditing Pulumi’s state file and dependencies for vulnerabilities. Also, adopting Policy as Code (PaC) enforces compliance and security standards.
50. How do you ensure your Pulumi code is modular and maintainable?
    • By defining reusable components with ComponentResource, organizing code into separate files and modules, and following coding best practices like clear naming conventions and comments, Pulumi code can remain modular. Keeping configurations DRY (Don’t Repeat Yourself) and using common patterns like factory functions for resources also promotes maintainability.