10 common platform engineering interview questions

What is platform engineering?

Platform engineering is the design and implementation of the internal tool sets and workflows that support and automate software engineering tasks. The resulting internal developer platforms (IDPs) assist developers throughout the entire SDLC.

A platform engineer is responsible for developing, deploying, maintaining and troubleshooting the IDPs that developers need. Platform engineers alleviate the need for development teams to take on those platform responsibilities. Developers can instead focus on projects, completing them faster and with more consistency than development teams that oversee their own tools and platforms.

Platform engineers provide several key services:

• Collaborate with development teams to understand each project's infrastructure and operational requirements.
• Write code in Java, Python or similar languages for automation and scripting.
• Build and maintain key services for application development, such as databases and APIs.
• Define and implement the local or cloud infrastructure that supports application deployments.
• Test and validate the infrastructure to ensure performance, capacity and resilience.
• Configure infrastructure components, such as servers, storage, networks and databases, and associated policies for application deployment.
• Monitor infrastructure for performance and problems, and handle updates, troubleshooting and optimizations.
• Evaluate the health and stability of applications running on the platform.

Platform engineering expertise

Platform engineering demands both hardware and software skills, depending on the business and developers' needs. A large business with an extensive local data center might require a heavy focus on hardware. Conversely, a business with comprehensive public cloud utilization might emphasize cloud APIs and other software-defined platform skills, with little hardware contact.

Consequently, platform engineers require a wide scope of knowledge and expertise, such as the following:

• Programming languages, like JavaScript, Python, Java and C++, and scripting languages, like Bash, PowerShell and Ruby, to create software needed to support the infrastructure.
• Software development practices, such as CI/CD pipelines and associated software tools. This includes tool deployment and maintenance, as well as pipeline optimization, to support changing software development needs.
• Networking and associated tools to define and design a network that ensures secure connectivity among servers, storage, users, applications and services.
• Local and cloud computing infrastructure elements -- servers, VMs and associated hypervisors, containers and orchestration technologies, storage resources and services like firewalls and load balancers -- to assemble infrastructures.
• Database applications, database design and query languages to support database use.
• Software debugging and hardware troubleshooting to identify faults, perform root cause analysis and implement prompt remediations as incidents occur.
• Monitoring, observability and analytical skills to oversee the integrity and performance of the infrastructure and its tools. This helps ensure that the platform is operating within acceptable parameters established by metrics and KPIs.

10 platform engineering interview questions

Interviews for platform engineering positions can be lengthy and complex. They typically include several rounds, which may include technical questions and example/test work. Employers have specific requirements that candidates should be aware of to assess how their background matches a potential employer's expectations.

While each interview situation is unique, there are some overarching questions candidates can expect. Here are 10 potential questions and example answers that candidates can review to prepare for their interview.

1. How do you collaborate with a development team?

Collaboration is essential to platform engineering, so interviewers want to evaluate a candidate's comfort in team settings. Successful candidates have strong collaboration and communication skills with all platform stakeholders, including development, engineering, business leadership and junior engineers. Successful candidates also demonstrate the ability to coach junior engineers and teams on platform initiative implementation.

2. What skills are most important for a platform engineer?

This is a broad background question intended to gauge a candidate's understanding of the role and their skills. Although specific skill requirements can vary, there are typically four general skill areas for a platform engineer:

• Software development skills. Coding, testing and deploying scripts, APIs, software-defined infrastructure and other platform-related services, such as containers and Kubernetes. The focus is often on a strong knowledge of the SDLC and rapid proof of concept using popular languages, such as Java, Python and Go.
• Infrastructure skills. Preferably at least three years of detailed experience with computing hardware and networking systems available locally, as a private cloud or across a range of public cloud providers, such as AWS, Azure and Google Cloud Platform.
• Troubleshooting and problem-solving skills. Skills to fix and maintain platforms and code that constitutes platforms. This includes strong analytical abilities and root cause analysis, as well as clear and consistent preventive practices.
• Communication and collaboration skills. Skills to facilitate design, deployment and support across the organization.

3. What is your platform development process?

The interviewer wants a sense of the process that a candidate uses to achieve project goals. Platform engineers must have strong CI/CD experience, comfort with infrastructures and APIs, and the skills to design, build and deploy applications and infrastructures in complex environments, like the public cloud. A candidate might respond with a general step-by-step approach for testing and deploying a new application or tool on the platform, as well as establishing performance metrics or KPIs.

4. Have you ever had to alter your design in response to changing requirements?

The interviewer wants to gauge how well a candidate handles the pressures of changing platform requirements, as well as business and stakeholder demands. Engineers often alter platform designs to meet those changes. Communication and collaboration skills are a major benefit here, and successful candidates underscore the positive outcomes of such changes, like the opportunity to rethink a design to improve performance or reliability. The best answers to this question embrace the benefits of design changes for the platform and the business.

5. What were the security requirements for the platforms you've developed?

Security is critical to modern business platforms, and it's common for employers to seek candidates with security certification. The interviewer needs to gauge the candidate's knowledge of security measures and how they've integrated security into past platform projects, such as the use of encryption techniques, data protection and retention, and attack prevention and mitigation. Candidates can provide numerous examples of security measures in past platform designs.

6. How do you approach documentation for platform design and processes?

Documentation is essential for effective configuration, troubleshooting, training and compliance assurance. Platform engineering demands comprehensive and timely documentation that details the complete infrastructure, supporting codebase, automated tooling, processes and best practices. Successful candidates should demonstrate thorough documentation techniques and explain how documentation serves the enterprise.

7. Explain your experience with ongoing platform maintenance or support

Platform engineers are not only responsible for infrastructure design and deployment, but also for platform maintenance and optimization over time. Maintenance efforts include the following:

• Install tooling to gather metrics and follow established KPIs.
• Use analytics to gauge the platform's availability and performance over time.
• Employ high-quality code and thoughtful design to scale the platform according to developer and business needs.

Such efforts can be complicated when multiple teams use platforms and, therefore, can require solid collaboration skills, as well as technical skills.

8. Tell me about your most critical incident and your troubleshooting solution

If a platform goes down, every project that relies on the platform also halts. This can result in costly and time-consuming project delays. Platforms fail for many reasons, such as hardware outages, code errors and bugs, configuration errors or malicious activity. Platform engineers must be expert troubleshooters and able to recognize incidents, identify errors, perform root cause analyses, implement corrective measures and apply preventative measures to forestall future problems.

9. Which programming languages do you know best? Are you learning any new languages?

Platform engineers must be skilled coders to build the specialized tooling that runs the platform. This may include tools, integrations like APIs that connect tools, automation scripts, cloud deployment templates and system configuration templates. Platform engineers often have more than three years of direct experience with popular programming languages, such as Java, Python and Go -- though some employers may have specific requirements. Successful candidates are also open to learning new programming languages.

10. What is a typical CI/CD workflow, and how often is that workflow updated?

Platform engineers have a dual need for SDLC workflow expertise. First, they need to use a CI/CD workflow to create their own platform-related code. Second, they must be CI/CD workflow experts to build and grow a platform that can meet developers' workflow needs.

Employers might ask this question to gauge a candidate's knowledge of the SDLC and CI/CD workflow, the consistency of a candidate's answer with the employer's current workflows, and how a candidate approaches changes and improvements to workflows. In addition, the discussion might also include the use of KPIs to measure workflow effectiveness.