What is Containerization?

Welcome to a new season of the Oracle University Podcast, where we delve deep into the world of OCI Container Engine for Kubernetes. Join hosts Lois Houston and Nikita Abraham as they ask senior OCI instructor Mahendra Mehra about the transformative power of containers in application deployment and why they're so crucial in today's software ecosystem.   Uncover key differences between virtualization and containerization, and gain insights into Docker components and commands.   Getting Started with Oracle Cloud Infrastructure: https://oracleuniversitypodcast.libsyn.com/getting-started-with-oracle-cloud-infrastructure-1   Networking in OCI: https://oracleuniversitypodcast.libsyn.com/networking-in-oci   OCI Identity and Access Management: https://oracleuniversitypodcast.libsyn.com/oci-identity-and-access-management   OCI Container Engine for Kubernetes Specialist: https://mylearn.oracle.com/ou/course/oci-container-engine-for-kubernetes-specialist/134971/210836   Oracle University Learning Community: https://education.oracle.com/ou-community   LinkedIn: https://www.linkedin.com/showcase/oracle-university/   X (formerly Twitter): https://twitter.com/Oracle_Edu   Special thanks to Arijit Ghosh, David Wright, Radhika Banka, and the OU Studio Team for helping us create this episode.   ---------------------------------------------------------   Episode Transcript:   00:00 Welcome to the Oracle University Podcast, the first stop on your cloud journey. During this series of informative podcasts, we’ll bring you foundational training on the most popular Oracle technologies. Let’s get started! 00:26 Lois: Hello and welcome to the Oracle University Podcast! I’m Lois Houston, Director of Innovation Programs with Oracle University, and with me is Nikita Abraham, Principal Technical Editor.  Nikita: Hi everyone! Welcome to a new season of the Oracle University Podcast. This time around, we’re going to delve into the world of OCI Container Engine for Kubernetes, or OKE. For the next couple of weeks, we’ll cover key aspects of OKE to help you create, manage, and optimize Kubernetes clusters in Oracle Cloud Infrastructure. 00:58 Lois: So, whether you’re a cloud native developer, Kubernetes administrator and developer, a DevOps engineer, or site reliability engineer who wants to enhance your expertise in leveraging the OCI OKE service for cloud native application solutions, you’ll want to tune in to these episodes for sure. And if that doesn’t sound like you, I’ll bet you will find the season interesting even if you’re just looking for a deep dive into this service. Nikita: That’s right, Lois. In today’s episode, we’ll focus on concepts of containerization, laying the foundation for your journey into the world of containers. And taking us through all this is Mahendra Mehra, a senior OCI instructor with Oracle University. 01:38 Lois: Hi Mahendra! We’re so glad to start our look at containerization with you today. Could you give us an overview? Why is it important in today's software world? Mahendra: Containerization is a form of virtualization, operates by running applications in isolated user spaces known as containers.  All these containers share the same underlying operating system. The container engine, pivotal in containerization technologies and container orchestration platforms, serves as the container runtime environment. It effectively manages the creation, deployment, and execution of containers. 02:18 Lois: Can you simplify this for a novice like me, maybe by giving us an analogy?  Mahendra: Imagine a container as a fully packaged and portable computing environment. It's like a digital suitcase that holds everything an application needs to run—binaries, libraries, configuration files, dependencies, you name it. And the best part, it's all encapsulated and isolated within container. 02:46 Nikita: Mahendra, how is containerization making our lives easier today?  Mahendra: In olden days, running an application meant matching it with your machine's operating system. For example, Windows software required a Windows machine. However, containerization has rewritten this narrative. Now, it's ancient history. With containerization, you create a single software package, a container that gracefully runs on any device or operating systems. What's fascinating is that these containers seamlessly run while sharing the host operating system. The container engine is like a shadow abstracted from the host operating system with limited access to underlying resources. Think of it as a super lightweight virtual machine. The beauty of this, the containerized application becomes a globetrotter, seamlessly running on bare metal within VMs or on the cloud platforms without needing tweaks for each environment. 03:52 Nikita: How is containerization different from traditional virtualization? Mahendra: On one side, we have traditional virtualization. It’s like having multiple houses on a single piece of land, and each house or virtual machine has its complete setup—wall, roofs, and utilities. This setup, while providing isolation, can be resource-intensive with each virtual machine carrying its entire operating system. Now, let's shift gears to containerization, the modern day superhero. Imagine a high-rise building where each floor represents a container. These containers share the same building or host operating system, but have their private space or isolated user space. Here's the magic. They are super lightweight, don't carry extra baggage of a full operating system and can swiftly move between different floors. 04:50 Lois: Ok, gotcha. That sounds pretty efficient! So, what are the direct benefits of containerization?  Mahendra: With containerization technology, there's less overhead during startup and no need to set up a separate guest OS for each application since they all share the same OS kernel. Because of this high efficiency, containerization is commonly used for packing up the many individual microservices that make up modern applications. Containerization unfolds a spectrum of benefits, delivering unparalleled portability as containers run uniformly across diverse platforms. This agility, fostered by open source container engines, empowers developers with cross-platform flexibility. The speed of containerized applications known for their lightweight nature reduces cost, boosts efficiency, and accelerates start times. Fault isolation ensures robustness, allowing independent operations without affecting others. Efficiency thrives as containers share the OS kernel and reusable layers, optimizing server utilization. The ease of management is achieved through orchestration platforms like Kubernetes automating essential tasks. Security remains paramount as container isolation and defined permissions fortify the infrastructure against malicious threats. Containerization emerges not just as a technology but as a transformative force, redefining how we build, deploy, and manage applications in the digital landscape. 06:37 Lois: It sure makes deployment efficient, scalability, and seamless! Mahendra, various components of Docker architecture work together to achieve containerization goals, right? Can you walk us through them? Mahendra: A developer or a DevOps professional communicates with Docker engine through the Docker client, which may be run on the same computer as Docker engine in case of development environments or through a remote shell. So whenever a developer fires a Docker command, the client sends them to the Docker Daemon which carries them out. The communication between the Docker client and the Docker host is usually taken place through REST APIs. The Docker clients can communicate with more than one Daemon at a time.  Docker Daemon is a persistent background process that manages Docker images, containers, networks, and storage volumes. The Docker Daemon constantly listens to the Docker API request from the Docker clients and processes them. Docker registries are services that provide locations from where you can store and download Docker images. In other words, a Docker registry contains repositories that host one or more Docker images. Public registries include Docker Hub and Docker Cloud and private registries can also be used. Oracle Cloud Infrastructure offers you services like OCIR, which is also called a container registry, where you can host your own private or public registry. 08:02 Do you want to stay ahead of the curve in the ever-evolving AI landscape? Look no further than our brand-new OCI Generative AI Professional course and certification. For a limited time only, we’re offering both the course and certification for free. So, don’t miss out on this exclusive opportunity to get certified on Generative AI at no cost. Act fast because this offer is valid only until July 31, 2024. Visit https://education.oracle.com/genai to get started. That’s https://education.oracle.com/genai. 08:39 Nikita: Welcome back! Mahendra, I’m wondering how virtual machines are different from containers. How do virtual machines work? Mahendra: A hypervisor or a virtual machine monitor is a software, firmware, or hardware that creates and runs virtual machines. It is placed between the hardware and the virtual machines, and is necessary to virtualize the server. Within each virtual machine runs a unique guest operating system. VMs with different operating systems can run on the same physical server. A Linux VM can sit alongside a Windows VM and so on. Each VM has its own binaries, libraries, and application that it services. And the VM may be many gigabytes in size. 09:22 Lois: What kind of benefits do we see from virtual machines? Mahendra: This technique provides a variety of benefits like the ability to consolidate applications into a single system, cost savings through reduced footprints, and faster server provisioning. But this approach has its own drawbacks. Each VM includes a separate operating system image, which adds overhead in memory and storage footprint. As it turns out, this issue adds complexity to all the stages of software development lifecycle, from development and test to production and disaster recovery as well. It also severely limits the portability of applications between different cloud providers and traditional data centers. And this is where containers come to the rescue.  10:05 Lois: OK…how do containers help in this situation? Mahendra: Containers sit on top of a physical server and its host operating system—typically, Linux or Windows. Each container shares the host OS kernel and usually the binaries and libraries as well. But the shared components are read only. Sharing OS resources such as libraries significantly reduces the need to reproduce the operating system code. A server can run multiple workloads with a single operating system installation. Containers are thus exceptionally lightweight. They are only megabytes in size and take just seconds to start. What this means in practice is you can put two or three times as many applications on a single server with containers than you can put on a virtual machine. Compared to containers, virtual machines take minutes to run and are order of magnitude larger than an equivalent container measured in gigabytes versus megabytes. 11:01 Nikita: So then, is there ever a time you should use a virtual machine? Mahendra: You should use a virtual machine when you want to run applications that specifically require a new OS, also when isolation and security are your priority over everything else. In most scenarios, a container will provide a lighter, faster, and more cost-effective solution than the virtual machines. 11:22 Lois: Now that we’ve discussed containerization and the different Docker components, can you tell us more about working with Docker images? We first need to know what a Dockerfile is, right?  Mahendra: A Dockerfile is a text file that defines a Docker image. You’ll use a Dockerfile to create your own custom Docker image. In other words, you use it to define your custom environment to be used in a Docker container. You'll want to create your own Dockerfile when existing images won't meet your project needs to different runtime requirements, which means that learning about Docker files is an essential part of working with Docker. Dockerfile is a step-by-step definition of building up a Docker image. It provides a set of standard instructions to be used in Dockerfile that Docker will execute when you issue a Docker build command. 12:09 Nikita: Before we wrap up, can you walk us through some Docker commands? Mahendra: Every Dockerfile must start with a FROM instruction. The idea behind this is that you need a starting point to build your image. It can be from scratch or from an existing image available in the Docker registry.  The RUN command is used to execute a command and will wait till the command finishes its execution. Since most of the images are Linux-based, a good practice is to set up a directory you will work in. That's the purpose of work directory line. It defines a directory and moves you in. The COPY instruction helps you to copy your source code into the image. ENV provides default values for variables that can be accessed within the containers. If your app needs to be reached from outside the container, you must open its listening port using the EXPOSE command. Once your application is ready to run, the last thing to do is to specify how to execute it. You must add the CMD line with the same command with all the arguments you used locally to launch your application. This command can also be used to execute commands at runtime for the containers, but we can be more flexible using the ENTRYPOINT command. Labels are used in Dockerfile to help organize your Docker images.   13:20 Lois: Thank you, Mahendra, for joining us today. I learned a lot! And if you want to learn more about working with Docker images, go to mylearn.oracle.com and search for the OCI Container Engine for Kubernetes Specialist course. The course is free so you can get started right away. Nikita: Yeah, a fundamental understanding of core OCI services, like Identity and Access Management, networking, compute, storage, and security, is a prerequisite to the course and will certainly serve you well when leveraging the OCI OKE service. And the quickest way to gain this knowledge is by completing the OCI Foundations Associate learning path on MyLearn and getting certified. You can also listen to episodes from our first season, called OCI Made Easy, where we discussed these topics. We’ll put a few links in the show notes so you can easily find them.  Lois: We’re looking forward to having Mahendra join us again next week when we’ll talk about container registries. Until next time, this is Lois Houston… Nikita: And Nikita Abraham signing off! 14:24 That’s all for this episode of the Oracle University Podcast. If you enjoyed listening, please click Subscribe to get all the latest episodes. We’d also love it if you would take a moment to rate and review us on your podcast app. See you again on the next episode of the Oracle University Podcast.