The Geeks Area

DOCKER 1. What is Docker? Docker is Open Source software. It provides the automation of Linux application deployment in a software container. We can do operating system level virtualization on Linux with Docker. Docker can package software in a complete file system that contains software code, runtime environment, system tools, & libraries that are required to install and run the software on a server. 2. What is the difference between Docker image and Docker container? Docker container is simply an instance of Docker image. A Docker image is an immutable file, which is a snapshot of container. We create an image with build command. When we use run command, an Image will produce a container. In programming language, an Image is a Class and a Container is an instance of the class. 3. How will you remove an image from Docker? We can use docker rmi command to delete an image from our local system. Exact command is: % docker rmi <Image Id> If we want to fin...

UNIX Shell 1. How will you remove all files in current directory? Including the files that are two levels down in a subdirectory. In Unix we have rm command to remove files and sub-directories. With rm command we have –r option that stands for recursive. The –r option can delete all files in a directory recursively. It means if we our current directory structure is as follows: My_dir ->Level_1_dir -> Level_1_dir ->Level_2_dir -> Level_1_dir ->Level_2_dir->a.txt With rm –r * command we can delete the file a.txt as well as subdirectories Level_1_dir and Level_2_dir. Command: rm – r * The asterisk (*) is a wild card character that stands for all the files with any name. 2. What is the difference between the –v and –x options in Bash shell scripts? In a BASH Unix shell we can specify the options –v and –x on top of a script as follows: #!/bin/bash -x –v With –x option BASH shell will echo the commands like for, select, case etc. after subst...

Microservices Interview Questions 1. What is a Microservice in Java? A Microservice is a small and autonomous piece of code that does one thing very well. It is focused on doing well one specific task in a big system. It is also an autonomous entity that can be designed, developed and deployed independently. Generally, it is implemented as a REST service on HTTP protocol, with technology-agnostic APIs. Ideally, it does not share database with any other service. 2. What are the benefits of Microservices architecture? Microservices provide many benefits. Some of the key benefits are: 1.      Scaling : Since there are multiple Microservices instead of one monolith, it is easier to scale up the service that is being used more. Eg. Let say, you have a Product Lookup service and Product Buy service. The frequency of Product Lookup is much higher than Product Buy service. In this case, you can just scale up the Product Lookup service to run on powerful ha...

Cloud Computing 1. What are the benefits of Cloud Computing? There are ten main benefits of Cloud Computing: Flexibility : The businesses that have fluctuating bandwidth demands need the flexibility of Cloud Computing. If you need high bandwidth, you can scale up your cloud capacity. When you do not need high bandwidth, you can just scale down. There is no need to be tied into an inflexible fixed capacity infrastructure. Disaster Recovery : Cloud Computing provides robust backup and recovery solutions that are hosted in cloud. Due to this there is no need to spend extra resources on homegrown disaster recovery. It also saves time in setting up disaster recovery. Automatic Software Updates : Most of the Cloud providers give automatic software updates. This reduces the extra task of installing new software version and always catching up with the latest software installs. Low Capital Expenditure : In Cloud computing the model is Pay as you Go. This means there is very...

Amazon Web Services 1. What do you know about AWS Region? An AWS Region is a completely independent entity in a geographical area. There are two more Availability Zones in an AWS Region. Within a region, Availability Zones are connected through lowlatency links. Since each AWS Region is isolated from another Region, it provides very high fault tolerance and stability. For launching an EC2 instance, we have to select an AMI within the same region. 2. What are the important components of IAM? The important components of IAM are as follows: 1.     IAM User : An IAM User is a person or service that will interact with AWS. User can sign into AWS Management Console for performing tasks in AWS. 2.     IAM Group : An IAM Group is a collection of IAM users. We can specify permission to an IAM Group. This helps in managing large number of IAM users. We can simply add or remove an IAM User to an IAM Group to manage the permissions. 3. ...