Chef Interview Questions And Answers

[TOP 100] Chef Interview Questions And Answers

Most Commonly Asked Chef Interview Questions And Answers

Chef Interview Questions And Answers are as follows –

Q1. What is Chef?

It is a powerful automation platform that provides a way to transforms infrastructure into code. Chef is a tool for which you write scripts that are used to automate processes. What processes? Pretty much anything related to IT.

Now you can explain the architecture of Chef, it consists of:

Chef Architecture Components
Chef Server The Chef Server is the central store of your infrastructure’s configuration data.

The Chef Server stores the data necessary to configure your nodes & provides search.

It is a powerful tool that allows you to dynamically drive node configuration based on data.

Chef Node A Node is any host that is configured using Chef-client.

Chef-client runs on nodes & contacts the Chef Server for the information necessary to configure node.

Nodes are sometimes referred as “clients” as they are machines that run the Chef-client software.

Chef Workstation A Chef Workstation is the host you use to modify your cookbooks and other configuration data.

All the configurations are first tested in the Chef Workstation.

Further, it is forwarded to the Chef Server

 

Q2. What is a Resource in Chef?

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. A block of Resource can be considered as a Recipe.

Q3. What is a Recipe in Chef?

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.

Q4. What is a Node in Chef?

A Node represents a server and is typically a virtual machine, container instance, or physical server – basically any compute resource in your infrastructure that is managed by Chef.

Q5. How does a Cookbook differ from a Recipe in Chef?

A Recipe is a collection of Resources, and primarily 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.

Q6. What is chef in devops?

Chef is a configuration management tool for dealing with machine setup on physical servers, virtual machines and in the cloud.
Many companies use Chef software to control and manage their infrastructure including Facebook, Etsy, Cheezburger, and Indiegogo.

Q7. What are Cookbooks in chef?

A cookbook is the fundamental unit of configuration and policy distribution. A cookbook defines a scenario and contains everything that is required to support that scenario:

Recipes that specify the resources to use and the order in which they are to be applied

Attribute values

File distributions

Templates

Extensions to Chef, such as custom resources and libraries

Q8. What is chef repo?

The chef-repo is a directory on your workstation that stores:

Cookbooks (including recipes, attributes, custom resources, libraries, and templates)

Roles

Data bags

Environments

The chef-repo directory should be synchronized with a version control system, such as git. All of the data in the chef-repo should be treated like source code.

Q9. What is chef-client Run?

A “chef-client run” is the term used to describe a series of steps that are taken by the chef-client when it is configuring a node.

Q10. What is chef validator?

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.

Q11. Why do we use SSL Certificates in chef?

An SSL certificate is used between the chef-client and the Chef server to ensure that each node has access to the right data.

Q12. What are Signed Headers in chef?

Signed header authentication is used to validate communications between the Chef server and any node that is being managed by the Chef server.

Q13. What is SSL_CERT_FILE in chef?

Use the SSL_CERT_FILE environment variable to specify the location for the SSL certificate authority (Cbundle that is used by the chef-client.

Q14. What are Knife Subcommands in chef?

The chef-client includes two knife commands for managing SSL certificates:

Use knife ssl check to troubleshoot SSL certificate issues

Use knife ssl fetch to pull down a certificate from the Chef server to the /.chef/trusted_certs directory on the workstation.

Q15. What is knife ssl check command in chef?

Run the knife ssl check subcommand to verify the state of the SSL certificate, and then use the reponse to help troubleshoot issues that may be present.

Q16. What is knife ssl fetch command in chef?

Run the knife ssl fetch to download the self-signed certificate from the Chef server to the /.chef/trusted_certs directory on a workstation.

Q17. What are Data Bags?

A data bag is a global variable that is stored as JSON data and is accessible from a Chef server. A data bag is indexed for searching and can be loaded by a recipe or accessed during a search.

Q18. What are recipes in chef?

A recipe is the most fundamental configuration element within the organization. A recipe:

  • Is authored using Ruby, which is a programming language designed to read and behave in a predictable manner
  • Is mostly a collection of resources, defined using patterns (resource names, attribute-value pairs, and actions); helper code is added around this using Ruby, when needed
  • Must define everything that is required to configure part of a system
  • Must be stored in a cookbook
  • May be included in a recipe
  • May use the results of a search query and read the contents of a data bag (including an encrypted data bag)
  • May have a dependency on one (or more) recipes
  • May tag a node to facilitate the creation of arbitrary groupings
  • Must be added to a run-list before it can be used by the chef-client
  • Is always executed in the same order as listed in a run-list

Q19. What is apt_package resource in chef?

Use the apt_package resource to manage packages on Debian and Ubuntu platforms.

apt_package Syntax:

A apt_package resource block manages a package on a node, typically by installing it. The simplest use of the apt_package resource is:

apt_package ‘package_name’

Q20. What is chef_gem?

Use the chef_gem resource to install a gem only for the instance of Ruby that is dedicated to the chef-client. When a gem is installed from a local file, it must be added to the node using the remote_file or cookbook_file resources.

Q21. What is chef_client resource?

A chef-client is an agent that runs locally on every node that is under management by Chef. When a chef-client is run, it will perform all of the steps that are required to bring the node into the expected state, including:

  • Registering and authenticating the node with the Chef server
  • Building the node object
  • Synchronizing cookbooks
  • Compiling the resource collection by loading each of the required cookbooks, including recipes, attributes, and all other dependencies
  • Taking the appropriate and required actions to configure the node
  • Looking for exceptions and notifications, handling each as required

Q22. What is chef_container resource?

chef_container resource is used to interact with container objects that exist on the Chef server.

Q23. What is chef_environment resource?

chef_environment resource to manage environments. An environment is a way to map an organization’s real-life workflow to what can be configured and managed when using Chef server. Every organization begins with a single environment called the _default environment, which cannot be modified (or deleted). Additional environments can be created to reflect each organization’s patterns and workflow.

Q24. What is chef_group resource?

chef_group resource is used to interact with group objects that exist on the Chef server.

Q25.What is chef_handler resource?

The chef_handler resource is used to enable handlers during a chef-client run. The resource allows arguments to be passed to the chef-client, which then applies the conditions defined by the custom handler to the node attribute data collected during the chef-client run, and then processes the handler based on that data.

Q26. What is the chef_mirror resource?

The chef_mirror resource to mirror objects in the chef-repo to a specified location.

Q27. What is chef_node resource?

A node is any machine—physical, virtual, cloud, network device, etc.—that is under management by Chef. chef_node resource is used to manage nodes.

Q28. What is chef_organization resource?

The chef_organization resource to interact with organization objects that exist on the Chef server.

Q29. What is chef_role resource?

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.

Q30. What is chef_user resource?

The chef_user resource is used to manage users.

Q31. What is cookbook_file resource?

The cookbook_file resource to transfer files from a sub-directory of COOKBOOK_NAME/files/ to a specified path located on a host that is running the chef-client.

Syntax – A cookbook_file resource block manages files by using files that exist within a cookbook’s /files directory. For example, to write the home page for an Apache website:

cookbook_file ‘/var/www/customers/public_html/index.php’ do

source ‘index.php’

owner ‘web_admin’

group ‘web_admin’

mode ‘0755’

action :create

end

Q32. What is metadata.rb in chef?

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.

Q33. What information stored in metadata.rb file?

A metadata.rb file is:

Located at the top level of a cookbook’s directory structure.

Compiled whenever a cookbook is uploaded to the Chef server or when the knife cookbook metadata subcommand is run, and then stored as JSON data.

Created automatically by knife whenever the knife cookbook create subcommand is run.

Edited using a text editor, and then re-uploaded to the Chef server as part of a cookbook upload.

Q34. What is Berkshelf in chef?

Berkshelf is a dependency manager for Chef cookbooks. With it, you can easily depend on community cookbooks and have them safely included in your workflow.

Q35. What is Berksfile in chef?

A Berksfile describes the set of sources and dependencies needed to use a cookbook. It is used in conjunction with the berks command.

Q36. What is kitchen (executable) in chef?

kitchen is the command-line tool for Kitchen, an integration testing tool used by the chef-client. Kitchen runs tests against any combination of platforms using any combination of test suites.

Q37. What is kitchen converge in chef?

Use the converge subcommand to converge one (or more) instances. Instances are based on the list of platforms in the .kitchen.yml file. This process will install the chef-client on an instance using the omnibus installer, upload cookbook files and minimal configuration to the instance, and then start a chef-client run using the run-list and attributes specified in the .kitchen.yml file.

Syntax – $ kitchen converge PLATFORMS (options)

Q38. What is kitchen create in chef?

Use the create subcommand to create one (or more) instances. Instances are based on the list of platforms and suites in the .kitchen.yml file.

Syntax – This subcommand has the following syntax:

$ kitchen create PLATFORMS (options)

Q39. What is kitchen destroy in chef?

Use the destroy subcommand to delete one (or more) instances. Instances are based on the list of platforms and suites in the .kitchen.yml file.

Syntax – This subcommand has the following syntax:

$ kitchen destroy PLATFORMS (options)

Q40. What is kitchen diagnose in chef?

Use the diagnose subcommand to show a computed diagnostic configuration for one (or more) instances. This subcommand will make all implicit configuration settings explicit because it echoes back all of the configuration data as YAML.

Syntax – This subcommand has the following syntax:

$ kitchen diagnose PLATFORMS (options)

Q41. What is kitchen driver create in chef?

Use the driver create subcommand to create a new Kitchen driver in the RubyGems project.

Syntax – This subcommand has the following syntax:

$ kitchen driver create NAME

Q42. What is kitchen driver discover?

Use the driver discover subcommand to discover Kitchen driver that have been published to RubyGems. This subcommand will return all RubyGems that are match kitchen-*.

Syntax – This subcommand has the following syntax:

$ kitchen driver discover

Q43. What kitchen exec in chef?

Use the exec subcommand to execute a command on a remote instance.

Syntax – This subcommand has the following syntax:

$ kitchen exec PLATFORMS (options)

Q44. What is kitchen init command in chef?

Use the init subcommand to create an initial Kitchen environment, including:

Creating a .kitchen.yml file

Appending Kitchen to the RubyGems file, .gitignore, and .thor

Creating the test/integration/default directory

Syntax – This subcommand has the following syntax:

$ kitchen init

Q45. What is kitchen list in chef?

Use the list subcommand to view the list of instances. Instances are based on the list of platforms in the .kitchen.yml file. Kitchen will auto-name instances by combining a suite name with a platform name. For example, if a suite is named default and a platform is named ubuntu-10.04, then the instance would be default-ubuntu-10.04. This ensures that Kitchen instances have safe DNS and hostname records.

Syntax – This subcommand has the following syntax:

$ kitchen list PLATFORMS (options)

Q46. What is kitchen login command in chef?

Use the login subcommand to log in to a single instance. Instances are based on the list of platforms and suites in the .kitchen.yml file. After logging in successfully, the instance can be interacted with just like any other virtual machine, including adding or removing packages, starting or stopping services, and so on. It’s a sandbox. Make any change necessary to help improve the coverage for cookbook testing.

Syntax – This subcommand has the following syntax:

$ kitchen login PLATFORM (options)

Q47. What is kitchen setup c0mmand in chef?

Use the setup subcommand to set up one (or more) instances. Instances are based on the list of platforms in the .kitchen.yml file.

Syntax – This subcommand has the following syntax:

$ kitchen setup PLATFORMS (options)

Q48. What is kitchen test command in chef?

Use the test subcommand to test one (or more) verified instances. Instances are based on the list of platforms and suites in the .kitchen.yml file. This subcommand will create a new instance (cleaning up a previous instance, if necessary), converge that instance, set up the test harness, verify the instance using that test harness, and then destroy the instance.

In general, use the test subcommand to verify the end-to-end quality of a cookbook. Use the converge and verify subcommands during the normal the day-to-day development of a cookbook.

Syntax – This subcommand has the following syntax:

$ kitchen test PLATFORMS (options)

Q49. What is kitchen verify command in chef?

Use the verify subcommand to verify one (or more) instances. Instances are based on the list of platforms and suites in the .kitchen.yml file.

In general, use the test subcommand to verify the end-to-end quality of a cookbook. Use the converge and verify subcommands during the normal the day-to-day development of a cookbook.

Syntax – This subcommand has the following syntax:

$ kitchen verify PLATFORMS (options)

Q50. What is kitchen version command in chef?

Use the version subcommand to print the version of Kitchen.

Syntax – This subcommand has the following syntax:

$ kitchen version

Q51. What are handlers in chef?

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.

Q52. How many types of handlers are there in chef? What are they?

In chef there are three types of handlers are there they are:

Exception Handler

Report Handler

Start Handler

Q53. What is exception handler in chef?

An exception handler is used to identify situations that have caused a chef-client run to fail. An exception handler can be loaded at the start of a chef-client run by adding a recipe that contains the chef_handler resource to a node’s run-list. An exception handler runs when the failed? property for the run_status object returns true.

Q54. What is a report handler in chef?

A report handler is used when a chef-client run succeeds and reports back on certain details about that chef-client run. A report handler can be loaded at the start of a chef-client run by adding a recipe that contains the chef_handler resource to a node’s run-list. A report handler runs when the success? property for the run_status object returns true.

Q56. What is start handler in chef?

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 cookbook.

Q57. What is Handler DSL in chef?

Use the Handler DSL to attach a callback to an event. If the event occurs during the chef-client run, the associated callback is executed. For example:

Sending email if a chef-client run fails

Sending a notification to chat application if an audit run fails

Aggregating statistics about resources updated during a chef-client runs to StatsD

Q58. What are the different Knife plugins for cloud hosting platforms?

There are different knife plugins available for cloud hosting platforms:

knife azure, knife bluebox, knife ec2, knife eucalyptus, knife google, knife linode, knife openstack, and knife rackspace

Q59. What is Ohai in chef?

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.

Q60. Why do we use chef-jenkins plugin in chef?

chef-jenkins adds the ability to use Jenkins to drive continuous deployment and synchronization of environments from a git repository.

Q61. Why do we use jclouds-chef plugin in chef?

jclouds-chef plugin adds Java and Clojure components to the Chef server API REST API.

Q62. Why do we use chef-hatch-repo in chef?

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.

Q63. Why do we use chef-trac-hacks in chef?

chef-trac-hacks adds the ability to fill a coordination gap between Amazon Web Services (AWS) and the chef-client.

Q64. What is chef-deploy plugin in chef and what is the purpose of using it?

chef-deploy adds a gem that contains resources and providers for deploying Ruby web applications from recipes.

Q65. What is kitchenplan in chef?

Kitchen plan is a utility for automating the installation and configuration of a workstation on macOS.

Q66. What is stove in chef?

Stove is a utility for releasing and managing cookbooks.

Q67. What are the benefits of Devops?

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)

Q68. What is Vagrant in chef?

Vagrant helps Test Kitchen communicate with VirtualBox and configures things like available memory and network settings.

Q69. What is chef in automation?

The chef is a powerful automation platform that transforms infrastructure into code.s 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 the chef-client.

Q70. What is chef DK?

The Chef DK workstation is the location where users interact with Chef. On the workstation users author and test cookbooks using tools such as Test Kitchen and interact with the Chef server using the knife and chef command line tools.

Q71. What are chef client nodes?

Chef client nodes are the machines that are managed by Chef. The Chef client is installed on each node and is used to configure the node to its desired state.

Q72. What is a chef server?

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 distributions.

Q73. What are work stations in chef?

A workstation is a computer running the Chef Development Kit (ChefDK) that is used to author cookbooks, interact with the Chef server, and interact with nodes.

The workstation is the location from which most users do most of their work, including:

  • Developing and testing cookbooks and recipes
  • Testing Chef code
  • Keeping the chef-repo synchronized with version source control
  • Configuring organizational policy, including defining roles and environments, and ensuring that critical data is stored in data bags
  • Interacting with nodes, as (or when) required, such as performing a bootstrap operation

Q74. What is the difference between chef-apply and chef-client?

This question must have been way ahead in the list of chef interview questions. However, some interviewers may pop it up even to experienced candidates. Chef-apply involves the application of a single recipe and Chef-client involves the application of a cookbook. Chef-apply provides a better understanding of the chef basics quickly and is ideal for learning purposes. On the other hand, chef-client is applicable for production purposes when one or more cookbooks should be applied.

Q75. What details do you need to bootstrap on Chef?

The following details are mandatory to bootstrap in Chef.

User name and password for logging into a specific node.

Host name of the node or public IP address.

Key-based authentication as a replacement of user name and password credentials.

Q76. How does Chef-apply differ from Chef-client?

Chef-apply is an executable program that runs a single recipe from the command line. It is a part of the Chef development kit and a great way to explore resources.

Syntax for Chef-apply is:

chef-apply name_of_recipe.rb

Chef-client applies a Cookbook. It is used for production purposes where you typically run Chef-client to apply one or more cookbooks.

Q77. How do you apply an updated Cookbook to your node in Chef?

There are three ways to apply an updated Cookbook to a node you can mention all or any one, I will suggest you to mention all three:

Run knife ssh from your workstation.

SSH directly into your server and run chef-client.

You can also run chef-client as a daemon, or service, to check in with the Chef server on a regular interval, say every 15 or 30 minutes.

Q78. What is the role of Starter Kit in Chef?

Begin this answer by mentioning the functions of Starter Kit.

Starter Kit will create the necessary configuration files like chef directory, knife.rb, the ORGANIZATION-validator.pem, and USER.pem files etc. with the correct information that is required to interact with the Chef server.

Now tell how to use Starter Kit, you can simply download the starter kit and then move it to the desired location on your workstation.

Q79. What is the command you use to upload a cookbook to the Chef server?

You can directly mention the command to upload a cookbook to the Chef server “knife cookbook upload”.

Q80. What would you set your cookbook’s version to once it is ready to use in production?

According to Semantic Versioning, you should set your cookbook’s version number to 1.0.0 once it is ready to use in production

Q81. Where can you get reusable cookbooks that are written and maintained by the Chef community?

You can directly answer this question by saying reusable Cookbooks are present at Chef Supermarket, https://supermarket.chef.io.

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