Containers are a method of building, packaging and deploying software. A container includes all the code, runtime, libraries and everything else the containerized workload needs to run.
Container deployment is the act of pushing (or deploying) containers to their target environment, such as a cloud or on-premises server. While a container might hold an entire application, in reality most container deployments are really multi-container deployments, meaning you are pushing multiple containers to the target environment. For more dynamic, large-scale systems, you might deploy hundreds or even thousands of containers a day.
They are designed to be spun up and down quickly depending on the application. This is because containers are often used as a method of building, packaging, and deploying microservices. Microservices describe a software architecture that breaks up a large solution—sometimes called a monolith or monolithic application—into smaller logical units. Each of these microservices then runs independently in its own container. There are myriad advantages to this modern software development practice, including the ability to speed up deployments and subsequent code changes.
Container deployments are well-suited to a variety of modern software and infrastructure strategies, including the aforementioned microservices approach. They can speed up application development and reduce the budget on IT operations teams, because they’re abstracted away from the environments they run in.
As a result, containerized applications have become a popular choice among DevOps teams and other organizations that have moved away from traditional monolithic (or “legacy”) approaches to software development. Container deployments also work well with continuous integration (CI) and continuous delivery (CD) processes and tools. (The related but distinct field of continuous deployment, another CD” acronym, takes continuous delivery a step further and fully automates the deployment of code to production, without requiring manual approval.)
Containers and related technologies such as orchestration tools appeal to modern software development teams because they offer multiple advantages. This is particularly true for teams working on digital transformation goals, or that simply need to deliver software products faster and more frequently than in the past. The benefits of container deployments include:
Speed: Containers can pave the way toward faster development and more frequent deployments, especially when used in CI/CD pipelines. Containers—along with container orchestration and increasing use of automation with CI/CD—tend to simplify the operational effort required to ship code to production, including in areas like infrastructure provisioning and testing.
Agility and flexibility: Containers are designed to be spun up and later deprecated quickly as needed. This means they can support fluid, evolving business goals and conditions. Their isolated nature, especially when used in conjunction with microservices architecture, can also lead to other advantages such as improved security control and the ability to update a containerized workload without having to redeploy the entire application.
Resource utilization and optimization: Containers are abstracted away from their underlying OS and infrastructure. This makes them lightweight and less demanding on system resources, which is a key difference from virtual machines, where every application must have its own guest OS. With containers, multiple applications can share the same OS, which in turns means multiple applications can run on shared resources on the same machine. This is sometimes referred to as density, meaning many containers can run on the same host.
Run anywhere: The fact that containers are abstracted away from their underlying OS and infrastructure also means they can run consistently in any environment. The code (and everything else it needs to run) will execute in the same manner no matter where your container is deployed. That could be a public or private cloud, an on-premises or hosted server, a developer’s laptop—containers are designed to run consistently everywhere.
There are a variety of tools available for container deployment. For example, Docker is a popular container platform and runtime that people and teams use to build and deploy containers. The starting point for using Docker for a container deployment is to build a Docker image for your container. You can also source an existing Docker image from Docker Hub repository, where people share prebuilt images for popular services and application needs. The Docker documentation has detailed technical instructions on getting started.
Various configuration management or infrastructure as code tools offer the means to create scripts that automate or partially automate container deployments, often working in tandem with a container platform like Docker. Each of these tools has their own particular methods—and technical instructions for automating a container deployment or the application’s configuration. You can use configuration management or infrastructure as code tools to write scripts—which go by different names on different platforms—to automate certain tasks in your container deployment and management based on configuration best practices.