218 lines
5.8 KiB
Markdown
218 lines
5.8 KiB
Markdown
# DevOps Interview Questions
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## Table of Contents
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1. [Jenkins](#jenkins)
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1. [AWS](#aws)
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1. [Network](#network)
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4. [Linux](#linux)
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## Jenkins
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###### beginner
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* Explain what is Jenkins and what is it used for
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* Explain each of the following in the context of nodes:
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* Master
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* Slave
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* Executor
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* Agent
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* Label
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* Explain each of the following in context of jobs:
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* Job
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* Build
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* Test
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* Artifacts
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* Explain the architecture of Jenkins
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* What are the different ways to trigger a build?
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* How do you start a build automatically upon a change in a certain repository?
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* What is a plugin?
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* What plugins are you using in Jenkins? Which do you consider to most useful?
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* Installation questions
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* How to install Jenkins?
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* How to install a plugin?
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* How to install an agent?
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###### Intermediate
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- What type of jobs there are?
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- How do you notify users on build results?
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- Can also be asked like that: what ways there are to notify users on build results?
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###### Advanced
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* Write a script to remove all the jobs which include the string "REMOVE_ME"
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## AWS
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###### Global Infrastructure
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- Explain the following
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- Availability zone
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- Region
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- Edge location
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###### S3 - beginner questions
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- Explain what is S3 and what is it used for
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- What is a bucket?
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- True or False? a bucket name must be globally unique
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- What objects in S3 consists of?
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- Another way to ask it: explain key, value, version id and metadata in context of objects
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- Explain data consistency
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- Can you host dynamic websites on s3? what about static websites?
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###### CloudFront
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- Explain what is CloudFront and what is it used for
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- Explain the following
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- Origin
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- Edge location
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- Distribution
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- What delivery methods available for the user with CDN?
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- True or False? object are cached for the life of TTL
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## Network
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Network questions can be found [here](https://github.com/bregman-arie/computer-networking/blob/master/interview_questions/README.md)
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## Linux
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* What is the different between a soft link and hard link?
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```
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hard link is the same file, using the same inode.
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soft link is a shortcut to another file, using a different inode.
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soft links can be created between different file systems while
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hard link can be created only within the same file system.
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```
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* How to run a process in background and why to do that in the first place?
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```
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You can achieve that by specifying & at end of the command.
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As to Why? since some commands/processes can take a lot of time to finish
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execution or run forever
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```
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* What signal is used when you run 'kill <process id>'?
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```
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The default signal is SIGTERM (15). This signal kills
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process gracefully which means it allows it to save current
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state configuration.
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followup questions:
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what is SIGKILL?
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what other signals there are?
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```
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## Ansible
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* Describe each of the following components in Ansible, including the relationship between them:
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* Task
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* Module
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* Play
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* Playbook
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* Role
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```
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Task – a call to a specific Ansible module
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Module – the actual unit of code executed by Ansible on your own host or a remote host. Modules are indexed by category (database, file, network, …) and also referred as task plugins.
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Play – One or more tasks executed on a given host(s)
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Playbook – One or more plays. Each play can be executed on the same or different hosts
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Role – Ansible roles allows you to group resources based on certain functionality/service such that they can be easily reused. In a role, you have directories for variables, defaults, files, templates, handlers, tasks, and metadata. You can then use the role by simply specifying it in your playbook.
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```
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* Write a task to create the directory ‘/tmp/new_directory’
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```
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- name: Create a new directory
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file:
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path: "/tmp/new_directory"
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state: directory
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```
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* What would be the result of the following play?
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```
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---
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- name: Print information about my host
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hosts: localhost
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gather_facts: 'no'
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tasks:
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- name: Print hostname
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debug:
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msg: "It's me, {{ ansible_hostname }}"
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```
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```
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When given a written code, always inspect it thoroughly. If your answer is “this will fail” then you are right. We are using a fact (ansible_hostname), which is a gathered piece of information from the host we are running on. But in this case, we disabled facts gathering (gather_facts: no) so the variable would be undefined which will result in failure.
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```
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* Write a playbook to install ‘zlib’ and ‘vim’ on all hosts if the file ‘/tmp/mario’ exists on the system.
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```
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---
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- hosts: all
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vars:
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mario_file: /tmp/mario
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package_list:
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- 'zlib'
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- 'vim'
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tasks:
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- name: Check for mario file
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stat:
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path: "{{ mario_file }}"
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register: mario_f
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- name: Install zlib and vim if mario file exists
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become: "yes"
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package:
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name: "{{ item }}"
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state: present
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with_items: "{{ package_list }}"
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when: mario_f.stat.exists
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```
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* Write a playbook to deploy the file ‘/tmp/system_info’ on all hosts except for controllers group, with the following content
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```
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I'm <HOSTNAME> and my operating system is <OS>
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```
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replace <HOSTNAME> and <OS> with the actual data for the specific host you are running on
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The playbook to deploy the system_info file
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```
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---
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- name: Deploy /tmp/system_info file
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hosts: all:!controllers
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tasks:
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- name: Deploy /tmp/system_info
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template:
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src: system_info.j2
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dest: /tmp/system_info
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```
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The content of the system_info.j2 template
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```
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# {{ ansible_managed }}
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I'm {{ ansible_hostname }} and my operating system is {{ ansible_distribution }
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```
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