Demystifying Docker101

Editor's Notes

• #4: Ajeet Singh Raina won the 2019 Captains Hat Award. Be sure to follow him on twitter and check out his blog at http://collabnix.com/ for great Docker content and learning materials.
• #13: Here’s my online store. As you can see its layered and modular. We have presentation layer exposing RESTAPI. Whenever the customer visit online store through browser in terms of HTML where he wants to just access the website OR might want to fetch information via RESTAPI.. There are various modules which implements different pieces of business functionality.
• #14: But when we use monolithic approach, we package them up as a single application. Just a big monolithic application. IN Java world it would be WAR file.. The application uses a database. Inside Del, most of the application which we built has this architecture.
• #17: Now online store became popular and grew with million of code
• #19: What we saw previously as a single stack application now become standalone, composable services
• #49: A container is similar to an application, which runs as a process on top of the operating system(OS) and isolates with each other by running in its own address space. Nevertheless, more than a normal process, a container not only includes the application executable, but also packs together all the necessary softwares that the application needs to run with, such as the libraries and the other dependencies. Cgroups [6] and namespaces [7] are two particular features that enables different containers running on the same physical machine. Cgroups, also named as control groups, is a Linux kernel mechanism to control the resources allocation. It allows
• #52: The kernel provides an API to these applications via system calls. OK, so you understand what a process is, and that containers are processes, but what about the files and programs that live inside a container image? These files and programs make up what is known as user space. When a container is started, a program is loaded into memory from the container image. Once the program in the container is running, it still needs to make system calls into kernel space. The ability for the user space and kernel space to communicate in a deterministic fashion is critical. User Space User space refers to all of the code in an operating system that lives outside of the kernel. Most Unix-like operating systems (including Linux) come pre-packaged with all kinds of utilities, programming languages, and graphical tools - these are user space applications. We often refer to this as “userland.”
• #54: docker inspect --format '{{.State.Pid}}
• #57: Docker uses a client-server architecture. The Docker client talks to the Docker daemon, which does the heavy lifting of building, running, and distributing your Docker containers. The Docker client and daemon can run on the same system, or you can connect a Docker client to a remote Docker daemon. The Docker client and daemon communicate using a REST API, over UNIX sockets or a network interface.
• #66: Docker Announces Docker Desktop Enterprise for Building and Deploying Container-based Solutions with Enterprise-Grade Security and Manageability New desktop application provides developers and IT the easiest, fastest and most secure way to deliver containerized applications from development to production  a new desktop product that is the e Enterprise Manageability That Helps Accelerate Time-to-Production asiest, fastest and most secure way to deliver enterprise production-ready containerized applications
• #67: The Application Designer is a new workflow that provides production-ready application and service templates that let you get coding quickly, with the reassurance that your application meets architectural standards. And even if you’ve never launched a container before, the Application Designer interface provides the foundational container artifacts and your organization’s skeleton code, getting you started with containers in minutes. Plus, Docker Desktop Enterprise integrates with your choice of development tools, whether you prefer an IDE or a text editor and command line interfaces.
• #74: A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image Docker builds images automatically by reading the instructions from a Dockerfile
• #77: Compose is a tool for defining and running multi-container Docker applications