Cracking the Chef and Puppet Interview: Your Ultimate Guide with Answers

If you’re aspiring to become a DevOps engineer or seeking a role that involves configuration management, you’ll likely encounter questions about Chef and Puppet during your interviews. These powerful tools are essential in the DevOps world, and demonstrating your expertise in them can significantly boost your chances of landing your dream job. In this comprehensive guide, we’ll dive into the most frequently asked Chef and Puppet interview questions, providing you with clear and concise answers to help you ace your next interview.

Understanding Chef and Puppet

Before we delve into the interview questions, let’s briefly define Chef and Puppet:

• Chef: Chef is an Infrastructure as Code (IaC) tool used for configuration management and automation. It allows you to define and automate the desired state of your infrastructure, ensuring consistent and repeatable deployments across various environments.

• Puppet: Puppet is another popular configuration management tool that follows a declarative approach. It allows you to define the desired state of your system resources and automatically enforces that state across your infrastructure.

Both Chef and Puppet are widely adopted in the DevOps community and play a crucial role in automating and streamlining IT infrastructure management.

Commonly Asked Chef and Puppet Interview Questions

1. What are Chef and Puppet used for?

   • Chef and Puppet are configuration management tools used to automate and streamline the process of managing and configuring IT infrastructure, including servers, applications, and services.
   • They allow you to define the desired state of your infrastructure as code, making it easier to provision, configure, and manage resources consistently across different environments.

2. What is a resource in Puppet?

   • In Puppet, a resource represents a piece of infrastructure and its desired state, such as a package that should be installed, a service that should be running, or a file that should be generated.
   • Resources are the building blocks of Puppet, and they define the actions that Puppet should take to enforce the desired state.

3. What is a node definition in Puppet?

   • A node definition, or node statement, is a block of Puppet code that is included only in the catalogs of matching nodes.
   • It allows you to assign specific configurations to specific nodes, enabling you to manage different systems with varying requirements.

4. How can Puppet help manage unique servers?

   • Puppet can help manage both consistency and uniqueness across servers.
   • It allows you to express the desired consistency that should exist, even if that consistency spans arbitrary sets of servers based on criteria like operating system, data center, or physical location.
   • Puppet also enables you to handle unique configurations by allowing you to specify exceptions or special provisions for what makes a given host unique.

5. How do you manage passwords on Red Hat Enterprise Linux, CentOS, and Fedora Core with Puppet?

   • To manage passwords on these systems with Puppet, you need the Shadow Password Library, which is provided by the ruby-shadow package.
   • This library is available natively for Fedora Core 6 (and higher) and can be used on the corresponding RHEL and CentOS variants.

6. How do you test your Puppet manifest files?

   • You can run syntax checks on your Puppet manifest files using the puppet parser validate command.
   • If you’re using an editor like Vim, you can use plugins like Syntastic to check the code.
   • You can also use tools like puppet-lint for additional linting and validation.
   • Writing RSpec or Cucumber tests for your Puppet code is another way to ensure its correctness.

7. Which scripting language is most important for a DevOps engineer?

   • Bash is the most commonly used UNIX shell for automation and is often the first choice for scripting tasks.
   • Perl is also widely used for text manipulation and database operations.
   • If you’re using Puppet or Chef, learning Ruby is beneficial, as many automation tools are built using Ruby.
   • Depending on the backend systems, Java might also be relevant for some DevOps tasks.

8. How does data fit into a DevOps workflow?

   • In an ideal DevOps world, the database administrator (DBA) is an integral part of both the Development and Operations teams, and data changes should be as seamless as code changes.
   • You should be able to version control and modify your data scripts just like your application code.
   • Choosing the right data storage solution (RDBMS, NoSQL, etc.) and designing your data schema properly can facilitate efficient testing and service virtualization, enabling successful DevOps adoption.

9. Describe the most significant gain you made by automating a process through Puppet.

   • Provide a specific example of how you automated the configuration and deployment of Linux and Windows machines using Puppet, reducing the deployment time from one week to ten minutes.
   • Mention how you used the roles and profiles paradigm and documented the purpose of each module in the README to ensure others could update the module using version control.
   • Highlight how your modules are still in use but have been improved by your teammates and the community.

10. What is Puppet Kick?

    • By default, the Puppet Agent requests a configuration catalog from the Puppet Master periodically, based on a configured “run interval.”
    • Puppet Kick is a utility that allows you to trigger the Puppet Agent from the Puppet Master, initiating an immediate configuration run.

11. Why shouldn’t you use auto-sign for all your clients?

    • While using auto-sign for all nodes can be tempting as it streamlines the bootstrapping process, it is considered a security risk.
    • With auto-sign enabled, a node could potentially masquerade as another node and obtain the configuration intended for that node.
    • The Puppet Master uses the certificate common name (CN) to look up the node definition and serve the appropriate configuration, but it does not enforce a one-to-one mapping between a node and the first certificate it saw.
    • Without auto-sign, any attempt to obtain another node’s configuration would be evident in the certificate signing process.

12. What happens during the Chef bootstrap process?

    • During the bootstrap process, the node downloads and installs the chef-client, registers itself with the Chef server, and performs an initial run.
    • In this initial run, the node applies any cookbooks that are part of its run-list.

13. What kinds of testing are needed in a DevOps environment?

    • DevOps teams should adopt a defensive programming mindset, assuming that code can fail and designing for those failures.
    • Testing strategies should include unit tests, test harnesses, early load testing, network simulation, A/B testing, and penetration testing, among others.

14. What other tools are you familiar with that can assist you in a DevOps role?

    • DevOps encompasses a wide range of tools and technologies, including data platforms (SQL, NoSQL), caching servers (Redis), issue tracking systems (Redmine), web servers (IIS, Apache), and more.
    • Familiarity with Agile application lifecycle management techniques and tools is also beneficial.

15. What is version control, and why should a version control system (VCS) be used?

    • Version control is a system that records changes made to one or more files and saves them in a centralized repository.
    • VCS tools allow developers to review changes over time, revert to previous versions, examine issues related to specific modifications, and collaborate simultaneously on the same file.
    • Using a VCS provides flexibility and enables better collaboration and change management.

16. How is Infrastructure as Code (IaC) implemented using AWS?

    • Explain how IaC replaces the traditional approach of writing commands into script files and testing them in a separate environment before deployment.
    • With AWS, IaC allows developers to write, test, and maintain infrastructure entities in a descriptive manner using formats like JSON or YAML, enabling easier development and faster deployment of infrastructure changes.

17. How can you provision systems with Puppet?

    • You can provision systems with Puppet using either a client/server architecture, utilizing the Puppet Agent and Puppet Master applications, or in a stand-alone mode, using the puppet apply application.

18. In Puppet, where is the code base configured?

    • The location of the code base is configured in puppet.conf with the codedir setting.
    • However, note that Puppet Server does not use that setting; instead, it uses its own jruby-puppet.master-code-dir setting in puppet-server.conf.
    • If you’re using a non-default code base location, you need to modify both settings.

19. What is the module layout in Puppet?

    • On disk, a Puppet module is a directory tree with a specific structure:
    Copy

    manifests/files/templates/lib/facts/examples/spec/functions/types/

20. Explain the process of installing modules from the Puppet Forge.

    • To install a module from the Puppet Forge, use the puppet module install command with the full name of the module you need.
    • For example, to install the puppetlabs-apache module: puppet module install puppetlabs-apache

21. What’s special about Puppet’s model-driven design?

    • Traditionally, managing the configurations of a large group of computers involved a series of imperative steps, such as SSH and a for loop.
    • Puppet takes a different approach by modeling everything – the system state, desired configuration state, and actions taken during configuration management – as data.
    • Each node receives a catalog of resources and relationships, compares it to the system state, and makes changes as necessary to bring the system into compliance.
    • Modeling systems as data allows Puppet to simulate configuration changes, track system history over its lifecycle, and prove that refactored manifest code still produces the same system state, among other benefits.

22. What size organizations should use Puppet?

    • There is no minimum or maximum organization size that can benefit from Puppet, but organizations with many servers are more likely to find value in using Puppet to eliminate manual management tasks.
    • Organizations with only a few servers may not consider server maintenance a real problem.

23. How do you document your Puppet manifests?

    • The Puppet language includes a simple documentation syntax, which is documented on the Puppet Manifest Documentation wiki page.
    • The puppet doc command uses this inline documentation to automatically generate RDoc or HTML documents for your manifests and modules.

24. What if you haven’t signed a Contributor License Agreement (CLA)?

    • If you haven’t signed a CLA, your code contributions cannot be accepted into Puppet or its issue tracker.
    • Signing a CLA is a simple process: log into your GitHub account and visit the CLA page to sign the agreement.
    • If you have any concerns or questions about past contributions and the CLA, contact the Puppet team for assistance.

25. How would you make a software deployable?

    • Discuss your understanding of concepts like Inversion of Control (IoC), Dependency Injection, scripted installations, test harnesses, separation of concerns, command-line tools, and Infrastructure as Code.
    • Explain how you would approach making software deployable and configurable in an automated and controlled manner.

26. How do you expect to multitask as a DevOps professional?

    • As a DevOps professional, you may be expected to:
    • Bridge communication gaps between Development and Operations teams.
    • Understand system design from an architect’s perspective, software development from a developer’s perspective, and operations and infrastructure from a sysadmin’s perspective.
    • Be able to execute tasks and get things done.

27. Describe two-factor authentication.

    • Two-factor authentication is a security process in which the user provides two means of identification from separate categories of credentials.
    • One factor is typically a physical token, such as a card, and the other is usually something memorized, like a security code.

28. What is your experience with cloud-based software development?

    • Discuss your experience with cloud platforms, provisioning instances, writing software iterations using cloud provider APIs or SDKs, configuring clusters for scalability, managing workflows, and handling big data workloads.
    • Mention your familiarity with container-based cloud instances and event-based cloud computing (e.g., AWS Lambda).
    • Highlight your experience with highly scalable cloud infrastructures for complex computing tasks, such as big data processing.

29. What was your greatest accomplishment on a recent project?

    • Choose an example that demonstrates your understanding of both development and operations aspects.
    • Avoid leaning too heavily towards one skillset while ignoring the other.
    • Ensure that your answer showcases your agility and ability to adapt to the organization’s needs.

30. What special training or education did it take for you to become a DevOps engineer?

    • Explain that DevOps is more of an attitude or philosophy than a specific skillset.
    • Highlight the importance of having a diverse skill set, including Linux systems administration, scripting, continuous integration/configuration management tools (Jenkins, Chef, etc.), structured programming, object-oriented design, and API development.
    • Emphasize your ability to learn new skills quickly to meet the requirements and your pattern recognition and experience-merging capabilities.

By thoroughly preparing for these Chef and Puppet interview questions, you’ll be well-equipped to demonstrate your expertise and stand out as a strong candidate for DevOps and configuration management roles. Remember, the key is to provide clear, concise, and well-structured answers that showcase your practical experience and problem-solving abilities.