Chef Interview Questions and Answers

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.

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 and provides search, 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 your nodes, contacting the Chef Server for the information necessary to configure the node. Since a Node is a machine that runs the Chef-client software, nodes are sometimes referred to as “clients”.

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 and then it is forwarded to the Chef Server.

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.

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.

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.

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.

run-list lets you specify which Recipes to run, and the order in which to run them. The run-list is important when you have multiple Cookbooks, and the order in which they run matters.

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.

Chef is an automation tool for keeping infrastructure as code. It has many benefits. Some of these are as follows:

Cloud Deployment: We can use Chef to perform automated deployment in Cloud environment.

Multi-cloud support: With Chef we can even use multiple cloud providers for our infrastructure.

Hybrid Deployment: Chef supports both Cloud based as well as datacenter-based infrastructure.

High Availability: With Chef automation, we can create high availability environment. In case of hardware failure, Chef can maintain or start new servers in automated way to maintain highly available environment.

Chef is composed of many components like Chef Server, Client etc. Some of the main components in Chef are as follows:

Client: These are the nodes or individual users that communicate with Chef server.

Chef Manage: This is the web console that is used for interacting with Chef Server.

Load Balancer: All the Chef server API requests are routed through Load Balancer. It is implemented in Nginx.

Bookshelf: This is the component that stores cookbooks. All the cookbooks are stored in a repository. It is separate storage from the Chef server.

PostgreSQL: This is the data repository for Chef server.

Chef Server: This is the hub for configuration data. All the cookbooks and policies are stored in it. It can scale to the size of any enterprise.

In Chef, use the bff_package resource to manage packages for the AIX platform using the installp utility. When a package is installed from a local file, it must be added to the node using the remote_file or cookbook_file resources.

The chef_acl resource to interact with access control lists that exist on the Chef server.

It is a collection of resources that describes a particular configuration.

See Example:

file ‘C:\Users\Administrator\chef-repo\settings.ini’ do

 content ‘greeting=hello world’

  end

is same as the below resource:

file ‘C:\Users\Administrator\chef-repo\settings.ini’ do

action :create

content ‘greeting=hello world’

end

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

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

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’

In Chef, 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.

The Chef DK is a special tool for workstation. The  installer is used to set up the Chef Development kit on a workstation, including the chef-client itself, an embedded version of Rubygems, OpenSSL, Ruby,Main key value stores.

By using this cookbook methods in Chef

• Knife SSH can be from the workstation
• Run the chef-client and then SSH in your server directly
• The chef-client can be used as a service and make it restarted after every selected time intervals say 15minutes or 20 minutes.

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.

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

In Chef, knife is a command-line tool that provides an interface between a local chef-repo and the Chef server. Knife helps users to manage:

• Nodes
• 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

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 : $ kitchen setup PLATFORMS (options)