What is Docker? Why it is popular?

Docker, a new container technology, is hotter than hot because it makes it possible to get far more apps running on the same old servers and it also makes it very easy to package and ship programs. Here's what you need to know about it.


All the noise is happening because companies are adopting Docker at a remarkable rate. At OSCon in July, I ran into numerous businesses that were already moving their server applications from virtual machines (VM) to containers. Indeed, James Turnbull, Docker's VP of services and support, told me at the conference that three of the largest banks that had been using Docker in beta were moving it into production. That's a heck of a confident move for any 1.0 technology, but it's almost unheard of in the safety-first financial world.


At the same time, Docker, an open-source technology, isn't just the darling of Linux powers such as Red Hat and Canonical. Proprietary software companies such as  Microsoft have also embraced Docker .

So why does everyone love containers and Docker? James Bottomley, Parallels‘ CTO of server virtualization and a leading Linux kernel developer, explained to me that VM hypervisors, such as Hyper-V, KVM, and Xen, all are "based on emulating virtual hardware. That means they’re fat in terms of system requirements."

Containers, however, use shared operating systems. That means they are much more efficient than hypervisors in system resource terms. Instead of virtualizing hardware, containers rest on top of a single Linux instance. This in turn means you can “leave behind the useless 99.9% VM junk, leaving you with a small, neat capsule containing your application,” said Bottomley.

Docker-VM-Container

Therefore, according to Bottomley, with a perfectly tuned container system, you can have as many as four-to-six times the number of server application instances as you can using Xen or KVM VMs on the same hardware.

Sounds great right? You get a lot more application bang for your server buck. So, why hasn't anyone done it before? Well, actually they have

Docker, however, is built on top of LXC. Like with any container technology, as far as the program is concerned, it has its own file system, storage, CPU, RAM, and so on. The key difference between containers and VMs is that while the hypervisor abstracts an entire device, containers just abstract the operating system kernel.

This, in turn, means that one thing hypervisors can do that containers can’t is to use different operating systems or kernels. So, for example, you can use Microsoft Azure to run both instances of Windows Server 2012 and SUSE Linux Enterprise Server, at the same time. With Docker, all containers must use the same operating system and kernel.

On the other hand, if all you want to do is get the most server application instances running on the least amount of hardware, you couldn't care less about running multiple operating system VMs. If multiple copies of the same application are what you want, then you'll love containers.

This move can save a data center or cloud provider tens-of-millions of dollars annually in power and hardware costs. It's no wonder that they're rushing to adopt Docker as fast as possible.

At the same time, developers can use Docker to pack, ship, and run any application as a lightweight, portable, self sufficient LXC container that can run virtually anywhere. As Bottomley told me, "Containers gives you instant application portability."

Last, but by no means least, Docker containers are easy to deploy in a cloud. As Ben Lloyd Pearson wrote in opensource.com, "Docker has been designed in a way that it can be incorporated into most DevOps applications, including Puppet, Chef, Vagrant, and Ansible, or it can be used on its own to manage development environments. The primary selling point is that it simplifies many of the tasks typically done by these other applications. Specifically, Docker makes it possible to set up local development environments that are exactly like a live server, run multiple development environments from the same host that each have unique software, operating systems, and configurations, test projects on new or different servers, and allow anyone to work on the same project with the exact same settings, regardless of the local host environment."

In a nutshell, here's what Docker can do for you: It can get more applications running on the same hardware than other technologies; it makes it easy for developers to quickly create, ready-to-run containered applications; and it makes managing and deploying applications much easier. Put it all together and I can see why Docker is riding the hype cycle as fast as I can recall ever seeing an enterprise technology go. I just hope that it can live up to its promise, or there will be some really upset CEOs and CIOs out there.

Source: http://www.zdnet.com/

Comments

Post a Comment

Popular posts from this blog

How SQL Indexes Work internally ?

Image
When an index is created, it records the location of values in a table that are associated with the column that is indexed. Entries are added to the index when new data is added to the table. When a query is executed against the database and a condition is specified on a column in the WHERE clause that is indexed, the index is first searched for the values specified in the WHERE clause. If the value is found in the index, the index returns the exact location of the searched data in the table. Figure 16.1 illustrates how an index functions. Suppose the following query was issued: SELECT *  FROM TABLE_NAME WHERE NAME = 'SMITH'; As shown in Figure 16.1, the NAME index is referenced to resolve the location of all names equal to 'SMITH'. After the location is determined, the data can be quickly retrieved from the table. The data, in this case names, is alphabetized in the index. A full table scan would occur if there were no index on the table and the same que...
Read more

UML,HLD and LLD.

UML is a standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems. Here is a Complete understanding of UML.   http://www.tutorialspoint.com/uml/index.html High Level Design (HLD) is the overall system design - covering the system architecture and database design. It describes the relation between various modules and functions of the system. data flow, flow charts and data structures are covered under HLD. Low Level Design (LLD) is like detailing the HLD. It defines the actual logic for each and every component of the system. Class diagrams with all the methods and relation between classes comes under LLD. Programs specs are covered under LLD. In HLD, you design the component level abstractions and interactions. In LLD, for each component, you go to the lower level such as class and method levels, describe what each class's responsibility, its interface and its interaction with other classes. All terms like "high...
Read more

Mutable and Immutable Objects

Mutable Objects:  When you have a reference to an instance of an object, the contents of that instance  can  be altered Immutable Objects:  When you have a reference to an instance of an object, the contents of that instance  cannot  be altered Immutability and Instances To demonstrate this behaviour, we'll use  java.lang.String  as the immutable class and  java.awt.Point  as the mutable class. Point myPoint = new Point( 0, 0 ); System.out.println( myPoint ); myPoint.setLocation( 1.0, 0.0 ); System.out.println( myPoint ); String myString = new String( "old String" ); System.out.println( myString ); myString.replaceAll( "old", "new" ); System.out.println( myString ); In case you can't see what the output is, here it is: java.awt.Point[0.0, 0.0] java.awt.Point[1.0, 0.0] old String old String We are only looking at a single instance of each object, but we can see that the contents of  myPoint  has change...
Read more