DevOps Chef Interview Questions & Answers

1. What is a chef in devops?
Answer: Chef is a configuration management tool for dealing with machine setup on physical servers, virtual machines and in the cloud. (chef interview questions)

2. What is a Node in Chef?
Answer: This will be probably the easiest question you can encounter answer this by saying: A Node represents a server and is typically a virtual machine, container instance, or physical server – basically, any computer resource in your infrastructure that is managed by Chef.

3. What is a chef server?
Answer: The Chef server acts as a hub for configuration data. The Chef server stores cookbooks, the policies that are applied to nodes, and metadata that describes each registered node that is being managed by Chef. Nodes use the Chef client to ask the Chef server for configuration details, such as recipes, templates, and file distribution.

4. What is metadata.rb in chef?
Answer: Every cookbook requires a small amount of metadata. A file named metadata.rb is located at the top of every cookbook directory structure. The contents of the metadata.rb file provides hints to the Chef server to help ensure that cookbooks are deployed to each node correctly.

5. What Is A Resource?
Answer: 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.

6. What is the one most important thing DevOps helps do?
Answer: The most important thing DevOps helps do is to get the changes into production as quickly as possible while minimizing risks in software quality assurance and compliance. That is the primary objective of DevOps. However, there are many other positive side-effects to DevOps. For example, clearer communication and better working relationships between teams which creates a less stressful working environment.

7. What are the advantages of NoSQL database over RDBMS?

The advantages are:

1. Less need for ETL
2. Support for unstructured text
3. Ability to handle change over time
4. Breadth of functionality
5. Ability to scale horizontally
6. Support for multiple data structures
7. Choice of vendors

8. How is Chef used as a CM tool?
Answer: The chef is considered to be one of the preferred industry-wide CM tools. Facebook migrated its infrastructure and backend IT to the Chef platform, for example. Explain how Chef helps you to avoid delays by automating processes. The scripts are written in Ruby. It can integrate with cloud-based platforms and configure new systems. It provides many libraries for infrastructure development that can later be deployed within a software. Thanks to its centralized management system, one Chef server is enough to be used as the center for deploying various policies.

9. What is Vagrant in chef?
Answer: Vagrant helps Test Kitchen communicate with Virtual Box and configures things like available memory and network settings.

10. How Does A Cookbook Differ From A Recipe?
Answer: A recipe is a collection of resources, and typically configures a software package or some piece of infrastructure. A cookbook groups together recipes and other information in a way that is more manageable than having just recipes alone.

For example, in this lesson, you used a template resource to manage your HTML home page from an external file. The recipe stated the configuration policy for your web site, and the template file contained the data. You used a cookbook to package both parts up into a single unit that you can later deploy.

11. What Is A Node?
Answer: A Node represents a server and is typically a virtual machine, container instance, or physical server – basically any compute resource in your infrastructure that’s managed by Chef.

12. What types of testing are needed?
Answer: Software teams will often look for the “fair weather” path to system completion; that is, they start from an assumption that software will usually work and only occasionally fail. I believe to practice defensive programming in a pragmatic way, which often means assuming that the code will fail and planning for those failures. I try to incorporate unit test strategy, use of test harnesses, early load testing; network simulation, A/B and multivariate testing, etc.

13. What’s your career objective in your role as a DevOps engineer?
Answer: My passion is breaking down the barriers and building and improving processes so that the engineering and operations teams work better and smarter. That’s why I love DevOps. It’s an opportunity to be involved in the entire delivery system from start to finish. (Online Training Institute)

14. What is the difference between RAID 0 and RAID 1?
Answer: RAID 1 offers redundancy through mirroring, i.e., data is written identically to two drives. RAID 0 offers no redundancy and instead uses striping, i.e., data is split across all the drives. This means RAID 0 offers no fault tolerance; if any of the constituent drives fails, the RAID unit fails.

15. What DevOps tools have you worked with?
Answer: Software configuration management and build/release (version control) tools, including Apache Subversion, Mercurial, Fossil and others, help document change requests. Developers can more easily follow the company’s best practices and policies while software changes.

Continuous integration (CI) tools such as Rational Build Forge, Jenkins and Semaphore merge all developer copies of the working code into a central version. These tools are important for larger groups where teams of developers work on the same codebase simultaneously. QA experts use code analyzers to test software for bugs, security, and performance. If you’ve used HP’s Fortify Static Code Analyzer, talk about how it identified security vulnerabilities in coding languages. Also speak about tools like Gramma Tech’s Code Sonar that you used to identify memory leaks, buffer underruns and other defects for C/C++ and Java code. It is essential that you have an adequate command of the principal languages like Ruby, C#, .NET, Perl, Python, Java, PHP, Windows Power Shell, and are comfortable with the associated OS environments Windows, Linux, and Unix.

16. What are Chef Resources and its functions?
Answer: When you group resources, it gets converted into a Recipe and this describes the working configuration and the policy. Using the Recipe, you can get all that is necessary for configuring a specific system.

So here we list some of the important functions of a Recipe:

With the Chef Recipe, you can install the software components
You can manage the files and apps deployment
You can execute the other recipes using one recipe.
17. Is there a difference between Agile and DevOps? If yes, please explain?
Answer: As a DevOps engineer, interview questions like this are quite expected. Start by describing the obvious overlap between DevOps and Agile. Although the implementation of DevOps is always in sync with Agile methodologies, there is a clear difference between the two. The principles of Agile are associated with seamless production or development of a piece of software. On the other hand, DevOps deals with the development, followed by deployment of the software, ensuring faster turnaround time, minimum errors, and reliability.

If you are preparing for senior DevOps roles, prepare for these specific Chef DevOps interview questions.

18. Why has DevOps gained prominence over the last few years?
Answer: Before talking about the growing popularity of DevOps, discuss the current industry scenario. Begin with some examples of how big players such as Netflix and Facebook are investing in DevOps to automate and accelerate application deployment and how this has helped them grow their business. Using Facebook as an example, you would point to Facebook’s continuous deployment and code ownership models and how these have helped it scale up but ensure the quality of experience at the same time. Hundreds of lines of code are implemented without affecting quality, stability, and security.

Your next use case should be Netflix. This streaming and on-demand video company follow similar practices with fully automated processes and systems. Mention the user base of these two organizations: Facebook has 2 billion users while Netflix streams online content to more than 100 millions users worldwide. These are great examples of how DevOps can help organizations to ensure higher success rates for releases, reduce the lead time between bug fixes, streamline and continuous delivery through automation, and an overall reduction in manpower costs.

19. What’s the run-list?
Answer: The run-list lets you specify which recipes to run, and the order in which to run them. The run-list is important for when you have multiple cookbooks and the order in which they run matters.

20. What is chef validator?
Answer: Chef-validator – Every request made by the chef-client to the Chef server must be an authenticated request using the Chef server API and a private key. When the chef-client makes a request to the Chef server, the chef-client authenticates each request using a private key located in /etc/chef/client.pem.

21. What is Berksfile in chef?
Answer: Berksfile describes the set of sources and dependencies needed to use a cookbook. It is used in conjunction with the berk’s command.

22. What is Chef role resource?
Answer: The chef_role resource to manage roles. A role is a way to define certain patterns and processes that exist across nodes in an organization as belonging to a single job function. Each role consists of zero (or more) attributes and a run-list. Each node can have zero (or more) roles assigned to it.

23. What is Knife and what is the purpose of using Knife in chef?
Answer: a Knife is a command-line tool that provides an interface between a local chef-repo and the Chef server. knife helps users to manage:

Cookbooks and recipes
Roles, Environments, and Data Bags
Resources within various cloud environments
The installation of the chef-client onto nodes
Searching of indexed data on the Chef server
24. Want to master all these DevOps tools?
Answer: Thoroughly describe any tools that you are confident about, what it’s abilities are and why you prefer using it. For example, if you have expertise in Git, you would tell the interviewer that Git is a distributed Version Control System (VCS) tool that allows the user to track file changes and revert to specific changes when required. Discuss how Git’s distributed architecture gives it an added edge where developers make changes locally and can have the entire project history on their local Git repositories, which can be later shared with other team members.

25. What information do you need in order to bootstrap in Chef?
Answer: Just mention the information you need in order to bootstrap:

Your node’s hostname or public IP address.
A user name and password you can log on to your node with.
Alternatively, you can use key-based authentication instead of providing a user name and password.
26. Why do we use the chef-Jenkins plugin in chef?
Answer: Chef-Jenkins adds the ability to use Jenkins to drive continuous deployment and synchronization of environments from a git repository.

27. What is start handler in chef?
Answer: A start handler is used to run events at the beginning of the chef-client run. A start handler can be loaded at the start of a chef-client run by adding the start handler to the start_handlers setting in the client.RB file or by installing the gem that contains the start handler by using the chef_gem resource in a recipe in the chef-client.

28. How Does Chef-apply Differ From Chef-client?
Answer: Chef-apply applies a single recipe; chef-client applies a cookbook.

For learning purposes, we had you start off with chef-apply because it helps you understand the basics quickly. In practice, chef-apply is useful when you want to quickly test something out. But for production purposes, you typically run chef-client to apply.

29. How would you prepare for migration?
Answer: This question evaluates your experience of real projects with all the awkwardness and complexity they bring. Include terms like cut-over, dress rehearsals, roll-back and roll-forward, DNS solutions, feature toggles, branch by abstraction, and automation in your answer. Developing greenfield systems with little or no existing technology in place is always easier than having to deal with legacy components and configuration. As a candidate, if you appreciate that any interesting software system will in effect be under constant migration, you will appear suitable for the role.

30. Explain the major components of Chef?
Answer: The architecture of Chef can be broken down into the Chef Server, Chef Workstation and Chef Node.

Chef Server: You can think of the Chef Server as the central store for that accumulates all the data that is necessary for configuring the nodes.

Chef Node: The Chef Node can be thought of as a client responsible for sharing data across the network and it is based on the chef-client architecture.

Chef Workstation: The Chef Workstation can be thought of as the host for modifying the configuration data and cookbooks which is then forwarded to the Chef Server. (chef interview questions)

31. Why do we use SSL Certificates in chef?
Answer: An SSL certificate is used between the chef-client and the Chef server to ensure that each node has access to the right data.

32. What is a chef in automation?
Answer: The chef is a powerful automation platform that transforms infrastructure into code.s The Chef server acts as a hub for configuration data.

33. What are handlers in chef?
Answer: Handlers are used to identify situations that arise during a chef-client run, and then tell the chef-client how to handle these situations when they occur.

34. What is Ohai in chef?
Answer: Ohai is a tool that is used to collect system configuration data, which is provided to the chef-client for use within cookbooks. Ohai is run by the chef-client at the beginning of every Chef run to determine system state. Ohai includes many built-in plugins to detect common configuration details as well as a plugin model for writing custom plugins.

35. Why do we use chef-Trac-hacks in chef?
Answer: Chef-Trac-hacks adds the ability to fill a coordination gap between Amazon Web Services (AWS) and the chef-client.

36. What are the benefits of Devops?
Answer: There are many benefits of using devops, explain about your devops experience.

Technical benefits:

Continuous software delivery
Less complex problems to fix
Faster resolution of problems
Business benefits:

Faster delivery of features
More stable operating environments
More time available to add value (rather than fix/maintain)
37. Explain the run-list in Chef?
Answer: The run-list is needed for specifying the Recipes that are needed for running it and the order in which the Recipes will be executed.

Some of the advantages of run-list include:

It ensures that the Recipes are running in the same order as specified
The node on which the run-list is to be executed has to be specified
It is transferred from the Workstation to Chef Server and the management console.
38. What happens when you don’t specify a resource’s action?
Answer: When you don’t specify a resource’s action, Chef applies the default action.

Question: The second recipe may not work as you’d expect because the service resource will fail if the package is not yet installed.

39. What is version control and why should VCS be used?

Define version control and talk about how this system records any changes made to one or more files and saves them in a centralized repository.
VCS tools will help you recall previous versions and perform the following:

Go through the changes made over a period of time and check what works versus what doesn’t.
Revert specific files or specific projects back to an older version.
Examine issues or errors that have occurred due to a particular change.
Using VCS gives developers the flexibility to simultaneously work on a particular file and all modifications can be logically combined later.
40. What Happens During The Bootstrap Process?
Answer: During the bootstrap process, the node downloads and installs chef-client, registers itself with the Chef server and does an initial check-in. During this check-in, the node applies any cookbooks that are part of its run-list.

41. How does HTTP work?
Answer: The HTTP protocol works in a client and server model like most other protocols. A web browser using which a request is initiated is called as a client and a web server software which responds to that request is called a server. World Wide Web Consortium and the Internet Engineering Task Force are two important spokes in the standardization of the HTTP protocol. HTTP allows improvement of its request and response with the help of intermediates, for example, a gateway, a proxy, or a tunnel. The resources that can be requested using the HTTP protocol, are made available using a certain type of URI (Uniform Resource Identifier) called a URL (Uniform Resource Locator). TCP (Transmission Control Protocol) is used to establish a connection to the application layer port 80 used by HTTP.

42. What testing is necessary to ensure that a new service is ready for production?
Answer: DevOps is all about continuous testing throughout the process, starting with development through to production. Everyone shares the testing responsibility. This ensures that developers are delivering code that doesn’t have any errors and is of high quality, and it also helps everyone leverage their time most effectively.

43. Describe two-factor authentication?
Answer: Two-factor authentication is a security process in which the user provides two means of identification from separate categories of credentials; one is typically a physical token, such as a card, and the other is typically something memorized, such as a security code.

44. What’s the background of your system?
Answer: Tips to answer: Some DevOps jobs require extensive systems knowledge, including server clustering and highly concurrent systems. As a DevOps engineer, you need to analyze system capabilities and implement upgrades for efficiency, scalability, and stability, or resilience. It is recommended that you have a solid knowledge of OSes and supporting technologies, like network security, virtual private networks, and proxy server configuration.

DevOps relies on virtualization for rapid workload provisioning and allocating compute resources to new VMs to support the next rollout, so it is useful to have in-depth knowledge around popular hypervisors. This should ideally include backup, migration, and lifecycle management tactics to protect, optimize and eventually recover computing resources. Some environments may emphasize microservices software development tailored for virtual containers. Operations expertise must include extensive knowledge of systems management tools like Microsoft System Center, Puppet, Nagios and Chef. DevOps jobs with an emphasis on operations require detailed problem-solving, troubleshooting and analytical skills.

45. How can you reduce the load time of a dynamic website?
Answer: Talk about Webpage optimization, cached web pages, quality web hosting, compressed text files, Apache fine-tuning.

46. Why are configuration management processes and tools important?
Answer: Talk about multiple software builds, releases, revisions, and versions for each software or testware that is being developed. Move on to explain the need for storing and maintaining data, keeping track of development builds and simplified troubleshooting. Don’t forget to mention the key CM tools that can be used to achieve these objectives. Talk about how tools like Puppet, Ansible, and Chef help in automating software deployment and configuration on several servers.

47. Why do we use chef-hatch-repo in chef?
Answer: Chef-hatch-repo plugin adds a knife plugin and a Vagrant provisioner that can launch a self-managed Chef server in a virtual machine or Amazon EC2.

48. What is a recipe?
Answer: A recipe is a collection of resources that describes a particular configuration or policy. A recipe describes everything that is required to configure part of a system. Recipes do things such as.

49. What is the role of AWS in DevOps?
Answer: When asked this question in an interview, get straight to the point by explaining that AWS is a cloud-based service provided by Amazon that ensures scalability through unlimited computing power and storage. AWS empowers IT enterprises to develop and deliver sophisticated products and deploy applications on the cloud. Some of its key services include Amazon CloudFront, Amazon SimpleDB, Amazon Relational Database Service, and Amazon Elastic Computer Cloud. Discuss the various cloud platforms and emphasize any big data projects that you have handled in the past using cloud infrastructure.

50. How would you make software deployable?
Answer: The ability to script the installation and reconfiguration of software systems is essential towards controlled and automated change. Although there is an increasing trend for new software to enable this, older systems and products suffer from the assumption that changes would be infrequent and minor, and so make automated changes difficult. As a professional who appreciates the need to expose configuration and settings in a manner accessible to automation, I will work with concepts like Inversion of Control (IoC) and Dependency Injection, scripted installation, test harnesses, separation of concerns, command-line tools, and infrastructure as code.

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