Hiring guide for Chef (software) Engineers

Chef (software) Developer Hiring Guide

Chef is an open-source configuration management tool, developed by Opscode in 2009, designed to streamline the task of configuring and maintaining a company's servers. It uses a pure-Ruby, domain-specific language for writing system configuration "recipes". Chef provides a framework for automated testing and deployment of applications and infrastructures. It is cloud-agnostic, supporting multiple cloud service providers, including AWS, Google Cloud, and Azure. Chef's source code is hosted on GitHub and its development is governed by the Chef Software company.

Ask the right questions secure the right Chef (software) talent among an increasingly shrinking pool of talent.

First 20 minutes

General Chef (software) app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Chef (software) application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you describe the role of Chef in DevOps?
Chef plays a crucial role in DevOps by automating the process of managing and deploying applications in dynamic environments. It helps in achieving speed, scale, and consistency.
What are some of the key components of Chef?
Some key components of Chef include the Chef Server, Workstation, and Nodes. The Chef Server is the central store of your infrastructure's configuration data. The Workstation is the location where users interact with Chef, and Nodes are the servers managed by Chef.
Describe the difference between a Chef recipe and a cookbook.
A Chef recipe is a collection of resources that describes a particular configuration or policy. A cookbook groups together recipes and other information necessary for deploying applications or settings to the system.
How would you handle data bags in Chef?
Data bags in Chef are used to store global variables that can be accessed from any node. They are managed through the Chef server and can be encrypted for security.
What are some common use cases for Chef?
Chef is commonly used for managing and configuring servers, automating infrastructure tasks, deploying applications, and ensuring that servers in an organization are consistently configured.
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What you’re looking for early on

Does the candidate have a strong understanding of Chef (software)?
Can the candidate demonstrate problem-solving skills?
How well does the candidate understand coding and scripting languages?
Does the candidate have experience with DevOps practices?

Next 20 minutes

Specific Chef (software) development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

Describe the difference between push and pull configurations in Chef.
In a push configuration, the server pushes the configuration to the nodes, while in a pull configuration, the nodes pull the configuration data from the server. Chef uses a pull-based configuration.
How would you use Chef to automate the process of setting up a new server?
You can use Chef to automate the process of setting up a new server by creating a cookbook that includes all the necessary recipes for the server's configuration. Then, you can use Chef to apply the cookbook to the new server.
What are the steps to bootstrap a node in Chef?
To bootstrap a node in Chef, you first need to install the Chef client on the node. Then, you can use the 'knife bootstrap' command to connect the node to the Chef server and apply the necessary cookbooks.
Describe the difference between Chef and other configuration management tools like Puppet or Ansible.
Chef, Puppet, and Ansible all serve the same purpose of automating infrastructure, but they have different approaches. Chef uses a pull-based configuration and is written in Ruby and Erlang. Puppet also uses a pull-based configuration but is written in Ruby. Ansible uses a push-based configuration and is written in Python.
How would you handle failures or errors in Chef?
Chef provides detailed error logs that can be used to troubleshoot and fix issues. It also supports 'dry run' mode, which allows you to see what changes would be made without actually applying them.
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The ideal back-end app developer

What you’re looking to see on the Chef (software) engineer at this point.

At this point, a skilled Chef (software) engineer should demonstrate strong problem-solving abilities, proficiency in Chef (software) programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Chef (software).

What does this simple Chef recipe do?
package 'httpd' do
  action :install
service 'httpd' do
  action [:enable, :start]
This Chef recipe installs the httpd package and then enables and starts the httpd service.
What does the following Chef code snippet do?
file '/tmp/something' do
  owner 'root'
  group 'root'
  mode '0755'
  action :create
This Chef code creates a file named 'something' in the '/tmp' directory. The owner and group of the file are set to 'root', and the file permissions are set to '0755'.
What will be the output of this code snippet in Chef?
items = ['apple', 'banana', 'cherry']
items.each do |item|
  log item do
    level :info
This code will log the items in the array one by one at the info level. So, it will output 'apple', 'banana', and 'cherry' separately in the logs.
What does this Chef code snippet do related to threading or concurrency?
bash 'long_running_process' do
  code <<-EOH
    sleep 60
  not_if 'pgrep long_running_process'
This Chef code runs a bash script that initiates a long running process (simulated with sleep 60). The 'not_if' guard ensures that the long running process is not started if it is already running, thus avoiding concurrency issues.

Wrap-up questions

Final candidate for Chef (software) Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Chef (software) application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are some best practices for writing Chef cookbooks?
Some best practices for writing Chef cookbooks include making them reusable and modular, using version control, testing cookbooks before deploying, and documenting all code.
How would you use Chef to manage multiple environments?
Chef supports the concept of 'environments' which can be used to manage different stages of your infrastructure, like development, testing, and production. You can define different attributes or cookbook versions for each environment.
Describe the difference between Chef Solo and Chef Server.
Chef Solo is a standalone mode where all the configurations are handled locally. Chef Server, on the other hand, allows you to manage multiple nodes and provides features like data storage and search.

Chef (software) application related

Product Perfect's Chef (software) development capabilities

Beyond hiring for your Chef (software) engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Chef (software) projects, and can engage in multiple capacities.