Industry Practices and Tools

1. What is the need for VCS?

Version control is incredibly important, especially in today's high-paced environment with increasingly shorter product release cycles. By tracking changes across all software assets and facilitating seamless collaboration, a version control system allow development and DevOps teams to build and ship better products faster.

Modern version control tools offer the following benefits:

• Protects Your Most Valuable Assets
• Scales Efficiently and Flexibly
• Tracks Changes Accurately
• Facilitates Seamless Team Collaboration

2.Differentiate the three models of VCSs, stating their pros and cons

• Local Data Model: This is the simplest variations of version control, and it requires that all developers have access to the same file system.

Advantages

• The user has complete control over access to your files and therefore it is really secure in comparison to an online storage where you don't know where your data is stored and who has access to your data
• The data can be accessed easily and quickly
• The user does not require an internet connection to access the document

Disadvantages

• Have to constantly keep back up of data to prevent loss
• The user is completely responsible for the safety of the data
• It is more difficult to share your data with others e.g. you need to upload on a hosted server and then either send an email or a link to the intended user
• Takes up more storage space if you store locally

• Client-Server Model: Using this model, developers use a single shared repository of files. It does require that all developers have access to the repository via the internet of a local network. This is the model used by Subversion (SVN).

Advantages

Organizations often seek  opportunities to maintain services and quality competition to sustain its market position with the help of technologies. Deployment of client-server computing in an organization will effectively increase its productivity through the usage of  cost-effective user interface, enhanced data storage, vast connectivity and reliable application services

• Improved Data Sharing: 

Data is retained by usual business processes and manipulated on a server is available for designated users (clients) over an authorized access.

• Integration of Services: 

Every client is given the opportunity to access corporate information via desktop interface eliminating the necessity to log into a terminal mode or processor. 

• Shared Resources Amongst Different Platforms: 

Application used for client-server model is built regardless of the hardware platform or technical background of the entitled software (operating system software) providing an open computing environment, enforcing users to obtain the services of clients and servers (database, application and communication services)

• Data Processing Capability Despite the Location: 

Client-server users can directly log into a system despite of the location or technology of the processors.

• Easy Maintenance: 

Client-server architecture is distributed model representing dispersed responsibilities among independent computers integrated across a network. Therefore, it's easy to replace, repair, upgrade and relocate a server while client remains unaffected. This unaware change is called as Encapsulation.

• Security: 

Servers have better control access and resources to ensure that only authorized clients can access or manipulate data and server updates are administered effectively.

Disadvantages

• Overloaded Servers: 

When there are frequent simultaneous client requests, server severely get overloaded, forming traffic congestion.

• Impact of Centralized Architecture: 

Since it is centralized, if a critical server failed, client requests are not accomplished. Therefore, client-server lacks the robustness of a good network.

• Distributed Model: In this model, each developer works directly with their own local repository, and changes are shared between repositories as a separate step. This is the model used by GIT, an open source software used by many of the largest software development projects.

Advantages

• Give more performance than single system
• If one pc in distributed system malfunction or corrupts then other node or pc will take care of
• More resources can be added easily
• Resources like printers can be shared on multiple pc’s

Disadvantages

• Security problem due to sharing
• Some messages can be lost in the network system
• Bandwidth is another problem if there is large data then all network wires to be replaced which tends to become expensive
• Overloading is another problem in distributed operating systems
• If there is a database connected on local system and many users accessing that database through remote or distributed way then performance become slow
• The databases in network operating is difficult to administrate then single user system

3.Git and GitHub, are they same or different? Discuss with facts.

Git is a distributed version control tool that can manage a development project's source code history, while GitHub is a cloud based platform built around the Git tool. Git is a tool a developer installs locally on their computer, while GitHub is an online service that stores code pushed to it from computers running the Git tool. The key difference between Git and GitHub is that Git is an open-source tool developers install locally to manage source code, while GitHub is an online service to which developers who use Git can connect and upload or download resources.

One way to examine the differences between GitHub and Git is to look at their competitors. Git competes with centralized and distributed version control tools such as Subversion, Mercurial, ClearCase and IBM's Rational Team Concert. On the other hand, GitHub competes with cloud-based SaaS and PaaS offerings, such as GitLab and Atlassian's Bitbucket.

GIT	GIT HUB
Installed locally.	Hosted in the cloud.
First released in 2005.	Company launched in 2008.
Maintained by the Linux Foundation.	Purchased in2018 by Microsoft.
Focused on version control and code sharing.	Focused on centralized source code hosting.
Primarily a command-line tool.	Administrated trough the web.
Provides a desktop interface name Git Gui.	Desktop interface named GitHub Desktop.
No user management features.	Built-in -user management.
Minimal external tool configuration features.	Active marketplace for tool integration.
Competes with Mercurial, Subversion,IBM, Relational Team concert and clearcse. And open source licensed.	Competes with Atlassian Bitbucket and GitLab. And includes a free tier and pay-for-use tiers.

4.Compare and contrast the Git commands, commit and push.

Basically Git commit "records changes to the repository" while git push "updates remote refs along with associated objects". So the first one is used in connection with your local repository, while the latter one is used to interact with a remote repository.

• Git commit record your changes to the local repository.

• Git push update the remote repository with your local changes.

5.Discuss the use of staging area and Git directory

1. staging helps you split up one large change into multiple commits - Let's say you worked on a large-ish change, involving a lot of files and quite a few different subtasks. You didn't actually commit any of these -- you were "in the zone", as they say, and you didn't want to think about splitting up the commits the right way just then. (And you're smart enough not to make the whole thing on honking big commit!). Now the change is all tested and working, you need to commit all this properly, in several clean commits each focused on one aspect of the code changes. With the index, just stage each set of changes and commit until no more changes are pending. Really works well with git gui if you're into that too, or you can use git add -p or, with newer gits, git add -e.
   
   
2. staging helps in reviewing changes - Staging helps you "check off" individual changes as you review a complex commit, and to concentrate on the stuff that has not yet passed your review. Let me explain. Before you commit, you'll probably review the whole change by using git diff. If you stage each change as you review it, you'll find that you can concentrate better on the changes that are not yet staged. git gui is great here. It's two left panes show unstaged and staged changes respectively, and you can move files between those two panes (stage/unstage) just by clicking on the icon to the left of the filename. Even better, you can even stage partial changes to a file. In the right pane of git gui, right click on a change that you approve of and choose "stage hunk". Just that change (not the entire file) is now staged; in fact, if there are other, unstaged, changes in that same file, you'll find that the file now appears on both top and bottom left panes.
   
   
3. staging helps when a merge has conflicts - When a merge happens, changes that merge cleanly are updated both in the staging area as well as in your work tree. Only changes that did not merge cleanly (i.e., caused a conflict) will show up when you do a git diff, or in the top left pane of git gui. Again, this lets you concentrate on the stuff that needs your attention -- the merge conflicts.
   
   
4. staging helps you keep extra local files hanging around - Usually, files that should not be committed go into .gitignore or the local variant, .git/info/exclude. However, sometimes you want a local change to a file that cannot be excluded (which is not good practice but can happen sometimes). For example, perhaps you upgraded your build environment and it now requires an extra flag or option for compatibility, but if you commit the change to the Makefile, the other developers will have a problem. Of course you have to discuss with your team and work out a more permanent solution, but right now, you need that change in your working tree to do any work at all! Another situation could be that you want a new local file that is temporary, and you don't want to bother with the ignore mechanism. This may be some test data, a log file or trace file, or a temporary shell script to automate some test... whatever. In git, all you have to do is never to stage that file or that change. That's it.
   
   
5. staging helps you sneak in small changes - Let's say you're in the middle of a somewhat large-ish change and you are told about a very important bug that needs to be fixed asap. The usual recommendation is to do this on a separate branch, but let's say this fix is really just a line or two, and can be tested just as easily without affecting your current work. With git, you can quickly make and commit only that change, without committing all the other stuff you're still working on. Again, if you use git gui, whatever's on the bottom left pane gets committed, so just make sure only that change gets there and commit, then push!

6.Explain the collaboration workflow of Git, with example.

Collaboration

In terms of Git process, collaboration is often about branching workflows. Thinking ahead on how you will intertwine commit trees will help you minimize integration bugs and support your release management strategy.

Workflow

A Git Workflow is a recipe or recommendation for how to use Git to accomplish work in a consistent and productive manner. Git workflows encourage users to leverage Git effectively and consistently. Git offers a lot of flexibility in how users manage changes. Given Git's focus on flexibility, there is no standardized process on how to interact with Git. When working with a team on a Git managed project, it’s important to make sure the team is all in agreement on how the flow of changes will be applied. To ensure the team is on the same page, an agreed upon Git workflow should be developed or selected. There are several publicized Git workflows that may be a good fit for your team. Here, we’ll be discussing some of these workflow options.

The array of possible workflows can make it hard to know where to begin when implementing Git in the workplace. This page provides a starting point by surveying the most common Git workflows for software teams.

As you read through, remember that these workflows are designed to be guidelines rather than concrete rules. We want to show you what’s possible, so you can mix and match aspects from different workflows to suit your individual needs.

A successful Git workflow

When evaluating a workflow for your team, it's most important that you consider your team’s culture. You want the workflow to enhance the effectiveness of your team and not be a burden that limits productivity. Some things to consider when evaluating a Git workflow are:

• Does this workflow scale with team size?
• Is it easy to undo mistakes and errors with this workflow?
• Does this workflow impose any new unnecessary cognitive overhead to the team?

Examples:

7.Discuss the benefits of CDNs.

1. Your reliability and response times get a huge boost

High performing website equals high conversion and growing sales. Latency and speed issues tend to cripple web businesses and cause damage. A few seconds can mean the difference between a successful conversion or a bounce. A reliable CDN ensures that the load speed is more than optimal and that online transactions are made seamlessly.

2. A CDN enables global reach

Over one third of the world’s population is online, which means that the global use of the internet has increased exponentially over the last 15 years. CDNs provide solutions through cloud acceleration with local POPs. This global reach will eliminate any latency problems that interrupt long-distance online transactions and cause slow load times.

3. A CDN saves a lot of money

Hiring a CDN results in noticeable savings for a business; rather than investing in an infrastructure and separate service providers all across the globe, a global CDN can eliminate the need to pay for costly foreign hosting and thus, save your business a lot of money. A global CDN offers a single platform to handle all of the separate operations, working across numerous regions for a reasonable price. CDNs are also recommended for companies with a tight budget.

4. 100% percent availability

Due to the distribution of assets across many regions, CDNs have automatic server availability sensing mechanisms with instant user redirection. As a result, CDN websites experience 100 percent availability, even during massive power outages, hardware issues or network problems.

5. Decrease server load

The strategic placement of a CDN can decrease the server load on interconnects, public and private peers and backbones, freeing up the overall capacity and decreasing delivery costs. Essentially, the content is spread out across several servers, as opposed to offloading  them onto one large server.

6. 24/7 customer support

Quality CDNs have been known for outstanding customer support. In other words, there is a CS team standby at all time, at your disposal. Whenever something occurs, you have  backup that’s waiting to help you fix your performance related problems. Having a support team on quick dial is a smart business decision – you’re not just paying for a cloud service, you’re paying for a large spectre of services that help your business grow on a global scale.

7. Increase in the number of Concurrent Users

Strategically placing the servers in a CDN can result in high network backbone capacity, which equates to a significant increase in the number of users accessing the network at a given time. For example, where there is a 100 GB/s network backbone with 2 tb/s capacity, only 100 GB/s can be delivered. However, with a CDN, 10 servers will be available at 10 strategic locations and can then provide a total capacity of 10 x 100 GB/s.

8. DDoS protection

Other than inflicting huge economic losses, DDoS attacks can also have a serious impact on the reputation and image of the victimized company or organization. Whenever customers type in their credit card numbers to make a purchase online, they are placing their trust in that business. DDoS attacks are on the rise and new ways of Internet security  are being developed; all of which have helped increase the growth of CDNs, as cloud security adds another layer of security.  Cloud solutions are designed to stop an attack before it ever reaches your data center. A CDN will take on the traffic and keep your website up and running. This means you need not be concerned about DDoS attacks impacting your data center, keeping your business’ website safe and sound.

9. Analytics

Content delivery networks can not only deliver content at a fast pace, they can also offer priceless analytical info to discover trends that could lead to advertising sales and reveal the strengths and the weaknesses of your online business. CDNs have the ability to deliver real-time load statistics, optimize capacity per customer, display active regions, indicate which assets are popular, and report viewing details to their customers. These details are extremely important, since usage logs are deactivated once the server source has been added to the CDN. Info analysis shows everything a developer needs to know to further optimize the website. In-depth reporting ultimately leads to performance increase, which results in higher user experience and then further reflects on sales and conversion rates.

Hiring a CDN is a growing trend in the internet community. Performance and security are everything – a CDN is here to deliver that. A high performance website creates income, growth, web presence and brand awareness. If your web business is suffering, you should consider hiring a CDN today.

8.How CDNs differ from web hosting servers?

1. Web Hosting is used to host your website on a server and let users access it over the internet. A content delivery network is about speeding up the access/delivery of your website’s assets to those users.
   
   
2. Traditional web hosting would deliver 100% of your content to the user. If they are located across the world, the user still must wait for the data to be retrieved from where your web server is located. A CDN takes a majority of your static and dynamic content and serves it from across the globe, decreasing download times. Most times, the closer the CDN server is to the web visitor, the faster assets will load for them.
   
   
3. Web Hosting normally refers to one server. A content delivery network refers to a global network of edge servers which distributes your content from a multi-host environment.

9.Identify free and commercial CDNs.

Free CDNs

• BootstrapCDN
• Cloudflare
• JSDelivr
• Coral Content Distribution Network (Defunct)
• Incapsula

Traditional commercial CDNs

• Akamai Technologies^[28]
• Amazon CloudFront^[28]
• Aryaka
• Azure CDN
• BelugaCDN^[28]
• CacheFly
• CDNetworks^[28]
• CenterServ^[28]
• ChinaCache
• Cloudflare^[28]
• Cotendo
• EdgeCast Networks
• Fastly
• Highwinds Network Group
• HP Cloud Services
• Incapsula
• Instart
• Internap
• LeaseWeb
• Level 3 Communications
• Limelight Networks
• MetaCDN
• NACEVI
• OnApp
• OVH
• Rackspace Cloud Files
• Speedera Networks
• StreamZilla
• Wangsu Science & Technology
• Webscale
• Yottaa

Commercial CDNs using P2P for delivery

• BitTorrent, Inc.
• Internap
• Pando Networks
• Rawflow

10.Discuss the requirements for virtualization.

Operating Systems	Microsoft Windows Server 2016 x64 Editions Microsoft Windows Server 2012 R2 x64 Editions Microsoft Windows Server 2012 x64 Editions Microsoft Windows Server 2008 x64 Editions
Hard Drive	500 GB recommended. Depending upon the number of virtual machines that you are planning to backup, ensure that the backup server computer has sufficient free space to store all virtual machine data.
Memory	16 GB RAM minimum required
Processor	All Windows-compatible processors supported
IIS	IIS must be enabled on the backup server.

11.Discuss and compare the pros and cons of different virtualization techniques in different

Levels.

Advantages of Virtualization

The advantages of switching to a virtual environment are plentiful, saving you money and time while providing much greater business continuity and ability to recover from disaster.

• Reduced spending. For companies with fewer than 1,000 employees, up to 40 percent of an IT budget is spent on hardware. Purchasing multiple servers is often a good chunk of this cost. Virtualizing requires fewer servers and extends the lifespan of existing hardware. This also means reduced energy costs.

• Easier backup and disaster recovery. Disasters are swift and unexpected. In seconds, leaks, floods, power outages, cyber-attacks, theft and even snow storms can wipe out data essential to your business. Virtualization makes recovery much swifter and accurate, with less manpower and a fraction of the equipment – it’s all virtual.

Better business continuity. With an increasingly mobile workforce, having good business continuity is essential. Without it, files become inaccessible, work goes undone, processes are slowed and employees are less productive. Virtualization gives employees access to software, files and communications anywhere they are and can enable multiple people to access the same information for more continuity.

• More efficient IT operations. Going to a virtual environment can make everyone’s job easier – especially the IT staff. Virtualization provides an easier route for technicians to install and maintain software, distribute updates and maintain a more secure network. They can do this with less downtime, fewer outages, quicker recovery and instant backup as compared to a non-virtual environment.

Disadvantages of Virtualization

The disadvantages of virtualization are mostly those that would come with any technology transition. With careful planning and expert implementation, all of these drawbacks can be overcome.

• Upfront costs. The investment in the virtualization software, and possibly additional hardware might be required to make the virtualization possible. This depends on your existing network. Many businesses have sufficient capacity to accommodate the virtualization without requiring a lot of cash. This obstacle can also be more readily navigated by working with a Managed IT Services provider, who can offset this cost with monthly leasing or purchase plans.

• Software licensing considerations. This is becoming less of a problem as more software vendors adapt to the increased adoption of virtualization, but it is important to check with your vendors to clearly understand how they view software use in a virtualized environment to a

• Possible learning curve. Implementing and managing a virtualized environment will require IT staff with expertise in virtualization. On the user side a typical virtual environment will operate similarly to the non-virtual environment. There are some applications that do not adapt well to the virtualized environment – this is something that your IT staff will need to be aware of and address prior to converting.

For many businesses comparing the advantages to the disadvantages, moving to a virtual environment is typically the clear winner. Even if the drawbacks present some challenges, these can be quickly navigated with an expert IT team or by outsourcing the virtualization process to a Managed IT Services provider. The seeming disadvantages are more likely to be simple challenges that can be navigated and overcome easily.

12.Identify popular implementations and available tools for each level of visualization.

Luckily visualization solutions are evolving as rapidly as the rest of the tech stack. Charts, videos, infographics and at the cutting edge even virtual reality and augmented reality (VR & AR) presentations offer increasingly engaging and intuitive channels of communication.

Here’s my run-down of some of the best, most popular or most innovative data visualization tools available today. These are all paid-for (although they all offer free trials or personal-use licences). Look out for another post soon on completely free and open source alternatives.

Tableau

Tableau is often regarded as the grand master of data visualization software and for good reason. Tableau has a very large customer base of 57,000+ accounts across many industries due to its simplicity of use and ability to produce interactive visualizations far beyond those provided by general BI solutions. It is particularly well suited to handling the huge and very fast-changing datasets which are used in Big Data operations, including artificial intelligence and machine learning applications, thanks to integration with a large number of advanced database solutions including Hadoop, Amazon AWS, My SQL, SAP and Teradata. Extensive research and testing has gone into enabling Tableau to create graphics and visualizations as efficiently as possible, and to make them easy for humans to understand.

Qlikview

Qlik with their Qlikview tool is the other major player in this space and Tableau’s biggest competitor. The vendor has over 40,000 customer accounts across over 100 countries, and those that use it frequently cite its highly customizable setup and wide feature range as a key advantage. This however can mean that it takes more time to get to grips with and use it to its full potential. In addition to its data visualization capabilities Qlikview offers powerful business intelligence, analytics and enterprise reporting capabilities and I particularly like the clean and clutter-free user interface. Qlikview is commonly used alongside its sister package, Qliksense, which handles data exploration and discovery. There is also a strong community and there are plenty of third-party resources available online to help new users understand how to integrate it in their projects.

FusionCharts

This is a very widely-used, JavaScript-based charting and visualization package that has established itself as one of the leaders in the paid-for market. It can produce 90 different chart types and integrates with a large number of platforms and frameworks giving a great deal of flexibility. One feature that has helped make FusionCharts very popular is that rather than having to start each new visualization from scratch, users can pick from a range of “live” example templates, simply plugging in their own data sources as needed.

Highcharts

Like FusionCharts this also requires a licence for commercial use, although it can be used freely as a trial, non-commercial or for personal use. Its website claims that it is used by 72 of the world’s 100 largest companies and it is often chosen when a fast and flexible solution must be rolled out, with a minimum need for specialist data visualization training before it can be put to work. A key to its success has been its focus on cross-browser support, meaning anyone can view and run its interactive visualizations, which is not always true with newer platforms.

Datawrapper

Datawrapper is increasingly becoming a popular choice, particularly among media organizations which frequently use it to create charts and present statistics. It has a simple, clear interface that makes it very easy to upload csv data and create straightforward charts, and also maps, that can quickly be embedded into reports.

Plotly

Plotly enables more complex and sophisticated visualizations, thanks to its integration with analytics-oriented programming languages such as Python, R and Matlab. It is built on top of the open source d3.js visualization libraries for JavaScript, but this commercial package (with a free non-commercial licence available) adds layers of user-friendliness and support as well as inbuilt support for APIs such as Salesforce.

Sisense

Sisense provides a full stack analytics platform but its visualization capabilities provide a simple-to-use drag and drop interface which allow charts and more complex graphics, as well as interactive visualizations, to be created with a minimum of hassle. It enables multiple sources of data to be gathered into one easily accessed repositories where it can be queried through dashboards instantaneously, even across Big Data-sized sets. Dashboards can then be shared across organizations ensuring even non technically-minded staff can find the answers they need to their problems.

13.What is the hypervisor and what is the role of it?

A hypervisor is a process that separates a computer’s operating system and applications from the underlying physical hardware. Usually done as software although embedded hypervisors can be created for things like mobile devices.

The hypervisor drives the concept of virtualization by allowing the physical host machine to operate multiple virtual machines as guests to help maximize the effective use of computing resources such as memory, network bandwidth and CPU cycles.

The explanation of a hypervisor up to this point has been fairly simple: it is a layer of software that sits between the hardware and the one or more virtual machines that it supports. Its job is also fairly simple. The three characteristics defined by Popek and Goldberg illustrate these tasks:

• Provide an environment identical to the physical environment
• Provide that environment with minimal performance cost
• Retain complete control of the system resources

14.How does the emulation is different from VMs?

For many, emulation and virtualization go hand in hand, but there are actually some really key differences. When a device is being emulated, a software-based construct has replaced a hardware component. Its possible to run a complete virtual machine on an emulated server. However, virtualization makes it possible for that virtual machine to run directly on the underlying hardware, without needing to impose an emulation tax (the processing cycles needed to emulate the hardware).

With virtualization, the virtual machine uses hardware directly, although there is an overarching scheduler. As such, no emulation is taking place, but this limits what can be run inside virtual machines to operating systems that could otherwise run atop the underlying hardware. That said, this method provides the best overall performance of the two solutions.

With emulation, since an entire machine can be created as a virtual construct, there are a wider variety of opportunities, but with the aforementioned emulation penalty. But, emulation makes it possible to, for example, run programs designed for a completely different architecture on an x86 PC. This approach is common, for example, when it comes to running old games designed for obsolete platforms on todays modern systems. Because everything is emulated in software, there is a performance hit in this method, although todays massively powered processors often cover for this.

Both methods are used for various purposes and are sometimes confused, so be aware of the differences.

15.Compare and contrast the VMs and containers/dockers, indicating their advantages and Disadvantages.

When it comes to cloud infrastructure, VMware has long been the go-to standard for its many advantages: its ability to run multiple OS environments that don’t affect each other, the choice of virtual machine types, and its consolidated toolkit that makes VM management easy. However, consider this: What if you had an alternative to VMware that was more lightweight, economical and more scalable? That’s exactly what Docker is - a container technology that lets users develop distributed applications.

What is a Virtual Machine?

The concept of a virtual machine is simple, really: it’s a virtual server that emulates a hardware server. A virtual machine relies on the system’s physical hardware to emulate the exact same environment on which you install your applications. Depending on your use case, you can use a system virtual machine (that runs an entire OS as a process, allowing you to substitute a real machine for a virtual machine), or process virtual machines that let you execute computer applications alone in the virtual environment.

What is Docker?

Docker is an open source project that offers a software development solution known as containers. To understand Docker, you need to know what containers are. According to Docker, a container is ” a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run it.” And since containers are platform-independent, Docker can run across both Windows- and Linux-based platforms. In fact, Docker can also be run within a virtual machine if need be. The main purpose of Docker is that it lets you run microservice applications in a distributed architecture.

Docker Architecture

Docker’s architecture is also client-server based. However, it’s a little more complicated than a virtual machine because of the features involved. It consists of four main parts:

1. Docker Client: This is how you interact with your containers. Call it the user interface for Docker.
2. Docker Objects: These are your main components of Docker: your containers and images. We mentioned already that containers are the placeholders for your software, and can be read and written to. Container images are read-only, and used to create new containers.
3. Docker Daemon: A background process responsible for receiving commands and passing them to the containers via command line.
4. Docker Registry: Commonly known as Docker Hub, this is where your container images are stored and retrieved.

Common Use Cases

Now that you have an idea of what VM and Docker containers are, it’s important to understand the potential use cases for both. While they are both more or less used to develop applications, here is where the differences really start.

Real-World Use Case for VMs

Starling Bank is a digital-only bank that was built in just one year on VMs provided by AWS. This is possible because of the efficiency virtual machines deliver over traditional hardware servers. Importantly, it cost Starling Bank just a tenth of traditional servers.

Real-World Use Case for Docker

Paypal uses Docker to drive “cost efficiency and enterprise-grade security” for its infrastructure. Paypal runs VMs and containers side-by-side and says that containers reduce the number of VMs it needs to run.

• Application development: Docker is primarily used to package an application’s code and its dependencies. The same container can be shared from Dev to QA and later to IT, thus bringing portability to the development pipeline.
• Running microservices applications: Docker lets you run each microservice that makes up an application in its own container. In this way, it enables a distributed architecture.

Docker Containers vs. VMs

At last, we arrive at the big question: how are the two different? It all comes down to what you want to do with them. Below, we’ll mention a few advantages of Docker as opposed to a virtual machine (specifically Docker vs. VMware), and vice versa.

Pricing comparison

• Docker: Free. Enterprise Edition starts at $750/node/year.
• VMware vSphere: Standard license starts at $995.

Advantages of Virtual Machines

• The tools associated with a virtual machine are easier to access and simpler to work with. Docker has a more complicated tooling ecosystem, that consists of both Docker-managed and third-party tools.

• As mentioned earlier, once you have a virtual machine up and running, you can start a Docker instance within that VM, and run containers within the VM (which is the predominant method of running containers at present). This way, containers and virtual machines are not mutually exclusive and can co-exist alongside each other.

Advantages of Docker Containers

• Docker containers are process-isolated and don’t require a hardware hypervisor. This means Docker containers are much smaller and require far fewer resources than a VM.
• Docker is fast. Very fast. While a VM can take an at least a few minutes to boot and be dev-ready, it takes anywhere from a few milliseconds to (at most) a few seconds to start up a Docker container from a container image.
• Containers can be shared across multiple team members, bringing much-needed portability across the development pipeline. This reduces ‘works on my machine’ errors that plague DevOps teams.