DevOps Interview Questions

Configuration management involves the systematic management of an organization's software and hardware configurations. It includes processes for version control, change management, and ensuring consistency and integrity in the configuration of systems.

DevOps methodology typically involves the following phases:

• Planning: Collaborative planning involving developers, operations, and other stakeholders to define project goals and requirements.
• Coding: Development of the application or system code by the development team.
• Building: Compilation of the code and creation of executable binaries or artifacts.
• Testing: Comprehensive testing, including unit, integration, and system testing, to ensure the code meets quality standards.
• Deployment: Release and deployment of the application or system to a target environment.
• Monitoring: Continuous monitoring of the application or system in the production environment to identify and address issues promptly.
• Operation: Routine maintenance, updates, and support activities to ensure the smooth operation of the application or system.
• Feedback: Continuous feedback loops to gather insights and improve processes throughout the development and operation lifecycle.

While both DevOps and Agile aim to enhance software development processes, they have different focuses:

• Agile Methodology: Primarily focuses on iterative development, collaboration, and flexibility in responding to changing requirements. It emphasizes delivering a minimal viable product (MVP) quickly.
• DevOps: Focuses on collaboration and communication between development and operations teams to enhance the entire software development lifecycle. It aims to automate processes, improve efficiency, and ensure faster and more reliable delivery of software.

• Continuous Deployment: Involves automatically deploying every code change that passes automated tests directly to the production environment, making it available for end-users without manual intervention.
• Continuous Delivery: Similar to continuous deployment, but the deployment to the production environment is a manual decision. Once the code passes automated tests, it is ready for deployment, but a human decision is required to push it to production.

DevOps antipatterns include:

• Silos: Lack of collaboration between development, operations, and other teams.
• Limited Automation: Failure to automate repetitive tasks, slowing down the development and deployment processes.
• Lack of Monitoring: Inadequate monitoring of applications in production, leading to delayed issue identification and resolution.
• Manual Processes: Heavy reliance on manual processes instead of automated pipelines, impeding efficiency.

Memcached: Memcached is an open-source, high-performance distributed memory caching system. It is designed to speed up dynamic web applications by reducing database load. Memcached stores key-value pairs in memory, allowing quick retrieval of data. It is commonly used to alleviate database load in large-scale web applications.

Common branching strategies include:

• Feature Branching: Each feature or task is developed in a separate branch, which is later merged into the main branch.
• Release Branching: A branch created for preparing a release, allowing bug fixes without affecting ongoing development.
• Gitflow Workflow: Defines specific branches for features, releases, and hotfixes, providing a structured approach to version control.

Key DevOps KPIs include:

• Deployment Frequency: How often code is deployed to production.
• Lead Time: Time taken from code commit to deployment.
• Change Failure Rate: The percentage of changes that result in failure in the production environment.
• Mean Time to Recovery (MTTR): Average time taken to recover from a failure in production.

CBD (Continuous Business Development): CBD in DevOps refers to the integration of business goals and processes into the DevOps practices. It emphasizes aligning development and operations with overall business objectives to ensure that software development contributes directly to business success.

Resilience Testing: Resilience testing, a part of DevOps, involves intentionally disrupting a system to observe how it behaves under stress or failure conditions. The goal is to identify weaknesses and enhance the system's ability to recover and continue functioning in the face of adverse events.

• Continuous Testing: Encompasses the entire testing process throughout the software development lifecycle, ensuring that testing is an integral part of each phase.
• Automated Testing: Involves using automated tools to execute pre-scripted tests on software applications, comparing actual outcomes with expected outcomes. It is a subset of continuous testing.

Ansible in DevOps: Ansible is an open-source automation tool used in DevOps for configuration management, application deployment, and task automation. It works by connecting to servers over SSH or PowerShell and uses simple YAML scripts (playbooks) to define configurations and tasks. Ansible helps in achieving consistency, repeatability, and efficiency in managing infrastructure and applications.

Ansible works by:

• Connecting to target servers using SSH or PowerShell.
• Sending modules (small programs) to the target servers to perform specific tasks.
• Executing tasks defined in YAML playbooks, describing the desired state of the system.
• Collecting and reporting results, allowing automation and management of configuration changes across multiple servers.

AWS (Amazon Web Services) in DevOps: AWS provides a range of cloud services that contribute to DevOps practices, including scalable computing power, storage, and databases. AWS services like AWS CodePipeline, AWS CodeBuild, and AWS CodeDeploy support continuous integration and deployment. Additionally, AWS offers infrastructure-as-code tools, enabling the automation of infrastructure provisioning and management.

Preparatory steps for adopting DevOps include:

• Cultural Transformation: Foster collaboration and communication among development and operations teams.
• Skill Development: Train teams in DevOps tools, practices, and automation.
• Toolchain Setup: Implement necessary tools for version control, continuous integration, deployment, and monitoring.
• Automation Strategy: Develop an automation strategy for testing, deployment, and infrastructure management.
• Metrics Definition: Identify key performance indicators (KPIs) to measure the success of DevOps practices.
• Continuous Improvement: Foster a culture of continuous improvement and feedback loops for ongoing enhancement.

In DevOps, "Shift left to reduce failure" refers to the practice of addressing and mitigating potential issues as early as possible in the software development and deployment lifecycle. Instead of dealing with problems only in the later stages, such as during testing or production, teams shift their focus to identifying and resolving issues in the earlier phases of development. This proactive approach involves integrating testing, security, and other quality assurance measures earlier in the process, ultimately reducing the likelihood of failures and improving overall software quality.

Yes, in DevOps, post-mortem meetings are conducted after incidents or outages to analyze and discuss what went wrong, why it happened, and how similar issues can be prevented in the future. These meetings encourage a blame-free and collaborative environment, aiming to learn from mistakes and improve the system's resilience. Key aspects include identifying root causes, documenting findings, and implementing corrective actions to enhance the overall reliability of the software or infrastructure.

The "sudo" (superuser do) command in Linux allows a permitted user to execute a command as the superuser or another user, as specified by the security policy configured in the sudoers file. It provides a way to perform administrative tasks without logging in as the root user, enhancing security by restricting privileged access to authorized individuals. Users granted sudo privileges can execute specific commands with elevated permissions, helping to prevent unauthorized and potentially harmful actions.

Jenkins follows a master-slave architecture. The Jenkins master server manages the build process, scheduling jobs, and distributing tasks to multiple Jenkins slave nodes for parallel execution. The master communicates with the slaves to allocate and monitor jobs. Jenkins supports plugins that extend its functionality, enabling integration with various tools and technologies. Users define build and deployment pipelines through job configurations, allowing for continuous integration and continuous delivery (CI/CD) in software development.

Infrastructure as Code (IaC) is a DevOps practice that involves managing and provisioning infrastructure using code, typically in a declarative and version-controlled manner. Instead of manually configuring servers and infrastructure components, IaC allows developers and operations teams to define infrastructure specifications using scripts or configuration files. This approach ensures consistency, repeatability, and version control, making it easier to deploy, scale, and manage infrastructure throughout its lifecycle.

Pair Programming is an agile software development technique where two programmers work together at one workstation. One person, the "driver," writes code, while the other, the "observer" or "navigator," reviews each line of code as it's written. The roles can switch frequently, promoting collaboration, knowledge sharing, and immediate feedback. Pair Programming is known for improving code quality, fostering communication, and enhancing the overall effectiveness of the development team.

The Blue/Green Deployment Pattern is a deployment strategy in which two identical production environments, referred to as "Blue" and "Green," coexist. At any given time, only one environment serves live production traffic while the other remains idle. When deploying updates or changes, the inactive environment is updated and validated. Once verified, the traffic is switched to the updated environment, making it the new production environment. This approach reduces downtime, allows quick rollback in case of issues, and ensures a seamless transition between versions.

The Dogpile effect, also known as cache stampede, occurs when multiple processes or threads attempt to regenerate the same cached data simultaneously after it expires. To prevent this, a cache lock mechanism can be implemented. When the cache expires, the first process to request the data obtains a lock and regenerates the cache. Subsequent processes are blocked until the cache is updated. This ensures that only one process regenerates the cache, preventing unnecessary load and resource contention.

To configure Git for pre-commit code sanity checking, follow these steps:

1. Create or identify the code sanity-checking script.
2. Integrate the script into the repository's pre-commit hook.
3. Make the hook executable.

To prevent further commits if sanity testing fails:

1. The hook should return a non-zero exit code if the sanity check fails.
2. Educate developers about the importance of pre-commit checks.
3. Implement branch protection in the repository settings to prevent direct pushes to protected branches, ensuring that all changes go through the sanity checks via pull requests.

To ensure a script runs with every git push, use Git hooks. Specifically, the pre-receive or post-receive server-side hooks can be employed. The pre-receive hook runs before updates are accepted into the repository, while the post-receive hook runs after the updates are accepted. These hooks can be configured to trigger custom scripts or actions, allowing you to enforce additional checks, tests, or actions before or after new commits are pushed to the repository.