AWS Interview Questions 1

1) Have you worked on containers ?

Containers are form of lightweight virtualization, more heavy than chroot but lighter than hypervisors. They provide isolation among processes while using same kernel as the host machine, and cgroups functionality within kernel. But container formats differ among themselves in a way that some provide more VM-like experience while other containerize only application.

LXC containers are most VM-like and most heavy weight, while Docker used to be more light weight and was initially designed for single application container. But in more recent releases Docker introduced whole machine containerization features so now Docker can be used both ways. There is also rkt from CoreOS and LXD from Canonical, which builds upon LXC.

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2) What is Kubernetes? Explain

It is massively scalable tool for managing containers, made by Google. It is used internally on huge deployments and because of that it is maybe the best option for production use of containers. It supports self healing by restating non responsive containers, it pack containers in a way that they take less resources and has many other great features.

3) What is the function of CI (Continuous Integration) server ?

CI server function is to continuously integrate all changes being made and committed to repository by different developers and check for compile errors. It needs to build code several times a day, preferably after every commit so it can detect which commit made the breakage if the breakage happens.

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Note: Other available and popular CI tools are Jenkins, TeamCity, CircleCI , Hudson, Buildbot etc

4) What is Continuous Delivery ?

Is it practice of delivering the software for testing as soon as it is build by CI (Continuous Integration) server’s. It requires heavy use of Versioning Control System for so always available to developers and testers alike.

5) What is Vagrant and what is it used for ?

Vagrant is a tool that can create and manage virtualized (or containerized) environments for testing and developing software. At first, Vagrant used virtualbox as the hypervisor for virtual environments, but now it supports also KVM.

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6) Do you ever used any scripting language ?

As far as scripting languages go, the simpler the better. In fact, the language itself isn’t as important as understanding design patterns and development paradigms such as procedural, object-oriented, or functional programming.

Currently, several scripting languages are available so the question arises : what is the most appropriate language for DevOps approach? Simply everything , it depends on the context of the project and tools used for example if Ansible used its good have knowledge in Python and if its for Chef its on Ruby.

7) What is the role of a configuration management tool in devops ?

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Automation plays an essential role in server configuration management. For that purpose we use CM tools , they store information about versions and builds of the software and testware and provide the traceability between software and testware.

8) What is the purpose of CM tools and which one you have used ?

Configuration Management tools’ purpose is to automatize deployment and configuration of software on big number of servers. Most CM tools usually use agent architecture which means that every machine being manged needs to have agent installed. My favorite tool is one that uses agentless architecture – Ansible. It only requires SSH and Python. And if raw module is being used, not even Python is required because it can run raw bash commands. Other available and popular CM tools are Puppet, Chef, SaltStack.

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9) What is OpenStack ?

OpenStack is often called Cloud Operating System, and that is not far from the truth. It is the complete environment for deploying IaaS which gives you possibility of making your own cloud similar to AWS. It is highly modular and consists of many sub-projects so you can pick and chose which functionality you need. OpenStack distribution are available from Red Hat, Mirantis, HPE, Oracle, Canonical and many others. It is completely open source project but some vendors make proprietary distributions.

10) Classify Cloud Platforms anategory ?

Cloud Computing software can be classified as Software as a Service or SaaS, Infrastructure as a Service or IaaS and Platform as a Service or PaaS.

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SaaS is peace of software that runs over network on remote server and has only user interface exposed to users, usually in web browser. For example salesforce.com.

Infrastructure as a service is a cloud environment that exposes VM to user to use as entire OS or container where you could install anything you would install on your server. Example for this would be OpenStack, AWS, Eucalyptus.

PaaS allows users to deploy their own application on the preinstalled platform, usually framework of application server and suite of developer tools. Examples for this would be OpenShHeroku.