{"id":82423,"date":"2026-09-22T17:24:29","date_gmt":"2026-09-22T20:24:29","guid":{"rendered":"https:\/\/a3aengenharia.com\/?post_type=articles&p=82423"},"modified":"2026-09-22T17:24:29","modified_gmt":"2026-09-22T20:24:29","slug":"what-is-docker-2","status":"publish","type":"articles","link":"https:\/\/a3aengenharia.com\/en-us\/content\/technical-articles\/what-is-docker-2\/","title":{"rendered":"What is Docker?"},"content":{"rendered":"\n

Docker<\/strong> is an open-source<\/a> platform that uses container<\/strong> technology to simplify the development, deployment, and execution of applications in isolated computing environments.<\/p>\n\n\n\n

In this article, we will understand what a container is, the main concepts related to Docker<\/strong>, and the impact this platform has on software development and system hosting.<\/p>\n\n\n\n

Read on.<\/p>\n\n\n

[elementor-template id=”24446″]<\/p>\n\n\n\n

What is a Container?<\/h2>\n\n\n\n

A container is a form of virtualization<\/a> at the operating-system level<\/strong>.<\/p>\n\n\n\n

Unlike hypervisor<\/a><\/em>-based virtualization (e.g., VMware and VirtualBox), which creates complete virtual machines with fully independent operating systems, containers share the host operating system kernel<\/a>, allowing multiple isolated user-space instances to run in the same environment.<\/p>\n\n\n\n

Platforms such as Docker drastically reduce resource overhead<\/a><\/em> and can accelerate startup time compared with virtual machines.<\/p>\n\n\n\n

\"\"
Representative diagram of containerization.
Source: The Docker Book | James Turnbull<\/a><\/figcaption><\/figure>\n\n\n\n

What is Docker used for?<\/h2>\n\n\n\n

Docker is a powerful tool that provides isolation through containers<\/strong>.<\/p>\n\n\n\n

Containers create isolated computing environments for testing and serve as consistent, reusable building blocks for services.<\/p>\n\n\n\n

Here are some examples of how Docker can be used:<\/p>\n\n\n\n

Testing Environment<\/h3>\n\n\n\n
    \n
  • Developers can create, run, and share Docker containers in their local environments.<\/li>\n\n\n\n
  • Containers built in the development environment can be promoted to testing and later to production, ensuring consistency across stages.<\/li>\n<\/ul>\n\n\n\n

    Self-Hosting<\/h3>\n\n\n\n

    Running independent services and applications<\/p>\n\n\n\n

      \n
    • Allows services and applications to run consistently across different environments.<\/li>\n\n\n\n
    • Ideal for service-oriented architectures and microservices-based deployments.<\/li>\n<\/ul>\n\n\n\n

      Application Development<\/h3>\n\n\n\n

      High-Performance Deployments<\/h3>\n\n\n\n

      Isolated testing in continuous integration (CI)<\/p>\n\n\n\n

        \n
      • Tools such as Jenkins CI use Docker to create isolated instances for running tests.<\/li>\n\n\n\n
      • Reduces the risk of interference among tests and improves CI-process reliability.<\/li>\n<\/ul>\n\n\n\n

        Building and testing complex architectures<\/p>\n\n\n\n

          \n
        • Allows complex applications to be replicated and tested on a local host before deployment to production environments.<\/li>\n<\/ul>\n\n\n\n

          Creating multi-user Platform-as-a-Service (PaaS) infrastructures<\/p>\n\n\n\n

            \n
          • Docker can provide the foundation for building platforms that support multiple users and services.<\/li>\n<\/ul>\n\n\n\n

            Lightweight, independent environments for learning and development<\/p>\n\n\n\n

              \n
            • Ideal for creating isolated sandboxes to:<\/li>\n\n\n\n
            • Test technologies such as Unix shells.<\/li>\n\n\n\n
            • Learn and teach programming languages.<\/li>\n\n\n\n
            • Run experiments without affecting the primary system.<\/li>\n<\/ul>\n\n\n\n

              SaaS (Software as a Service) applications<\/p>\n\n\n\n

                \n
              • Docker can be used to build and deploy SaaS applications, enabling efficient management and scalability.<\/li>\n<\/ul>\n\n\n\n

                High-performance and hyperscale deployments<\/p>\n\n\n\n

                  \n
                • Containers are extremely lightweight, allowing multiple hosts to be configured quickly to meet large-scale demand.<\/li>\n<\/ul>\n\n\n\n

                  How does Docker work?<\/h2>\n\n\n\n

                  Docker introduces an application-deployment mechanism based on a runtime environment that uses virtualized containers.<\/p>\n\n\n\n

                  This mechanism provides an efficient workflow that facilitates moving code from the local development environment to testing and then to production.<\/p>\n\n\n\n

                  Docker Architecture<\/h3>\n\n\n\n

                  Docker uses a client-server architecture.<\/p>\n\n\n\n

                  The Docker client<\/strong> communicates with the Docker server (daemon)<\/strong>, which performs the more complex operations, such as creating, running, and distributing Docker containers.<\/p>\n\n\n\n

                  The Docker client and daemon can run on the same system or remotely, with the client connecting to a daemon located on another machine.<\/p>\n\n\n\n

                  Communication between client and daemon uses a REST API<\/strong>, which can operate through UNIX sockets or network interfaces.<\/p>\n\n\n\n

                  \"\"<\/figure>\n\n\n\n

                  Docker Client<\/h4>\n\n\n\n

                  The Docker client<\/strong> (docker<\/code>) is the primary interface users employ to interact with Docker.<\/p>\n\n\n\n

                  When you run commands such as docker run<\/code>, the client sends those instructions to the daemon (dockerd<\/code>), which executes them.<\/p>\n\n\n\n

                  The Docker client uses the Docker API<\/strong> and can connect to multiple daemons simultaneously.<\/p>\n\n\n\n

                  Docker Server (Daemon)<\/h4>\n\n\n\n

                  The Docker daemon<\/strong> (dockerd<\/code>) listens for Docker API<\/strong> requests and manages Docker objects such as images, containers, networks, and volumes.<\/p>\n\n\n\n

                  The daemon can also communicate with other daemons to manage Docker services in a distributed environment.<\/p>\n\n\n\n

                  Docker Objects<\/h4>\n\n\n\n

                  When using Docker, you create and manipulate objects such as images<\/strong>, containers<\/strong>, networks<\/strong>, volumes<\/strong>, plugins<\/strong>, and others.<\/p>\n\n\n\n

                  Images<\/h5>\n\n\n\n

                  An image<\/strong> is a read-only template containing instructions for creating a Docker container.<\/p>\n\n\n\n

                  An image is usually based on another existing image with some customizations. For example, you can create an image based on the ubuntu<\/code> image and add the Apache web server, the application you want to run, and the configuration required for it to work.<\/p>\n\n\n\n

                  You can create your own images or use images made available by other users in public registries.<\/p>\n\n\n\n

                  To build an image, you need to create a Dockerfile<\/strong>.<\/p>\n\n\n\n

                  The Dockerfile uses a simple syntax to define the steps required to create and run the image.<\/p>\n\n\n\n

                  Each instruction in the Dockerfile creates a layer in the image.<\/p>\n\n\n\n

                  When the Dockerfile is modified and the image is rebuilt, only the changed layers are recreated. This makes images lightweight, compact, and fast, especially compared with other virtualization technologies.<\/p>\n\n\n\n

                  Containers<\/h5>\n\n\n\n

                  A container<\/strong> is a runnable instance of an image.<\/p>\n\n\n\n

                  You can create, start, stop, move, or delete a container using the Docker API<\/strong> or Docker CLI<\/strong>.<\/p>\n\n\n\n

                  You can also connect a container to one or more networks, attach storage, or create a new image based on the container\u2019s current state.<\/p>\n\n\n\n

                  By default, containers are well isolated from one another and from the host system. The level of isolation for networks, storage, and other subsystems can be configured according to requirements.<\/p>\n\n\n\n

                  A container is defined by its image and the configuration options provided when it is created or started.<\/p>\n\n\n\n

                  When a container is removed, any state change not stored in a persistent volume is lost.<\/p>\n\n\n\n

                  Registries<\/h4>\n\n\n\n

                  A Docker registry<\/strong> stores Docker images.<\/p>\n\n\n\n

                  Docker Hub<\/strong> is the default public registry, available to any user, from which Docker retrieves images by default.<\/p>\n\n\n\n

                  You can also configure and operate a private registry.<\/p>\n\n\n\n

                  Commands such as docker pull<\/code> or docker run<\/code> cause Docker to download the required images from the configured registry.<\/p>\n\n\n\n

                  Conversely, the docker push<\/code> command allows you to upload your images to the configured registry.<\/p>\n\n\n\n

                  Installing Docker<\/h2>\n\n\n\n

                  <\/h2>\n","protected":false},"excerpt":{"rendered":"

                  Docker is an open-source container platform for developing, deploying, and running applications in isolated environments. Learn the main concepts, architecture, images, containers, registries, and common use cases.<\/p>\n","protected":false},"author":1,"featured_media":27944,"parent":0,"template":"","meta":{"_a3a_global_related_solutions":[],"_a3a_global_related_services":[],"_a3a_global_related_materials":[],"_a3a_post_lang":"en-us","_a3a_translation_group_id":"3fdac2b7-99a4-4083-b23b-a368cc4260a2","_a3a_i18n_canonical_slug":"what-is-docker-2","_a3a_prod_post_id":"","_a3a_lang_url_en-us":"","_a3a_lang_url_es-es":""},"categories":[],"segments":[],"mercados":[],"etapas":[],"class_list":["post-82423","articles","type-articles","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles\/82423","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles"}],"about":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/types\/articles"}],"author":[{"embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":1,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles\/82423\/revisions"}],"predecessor-version":[{"id":82425,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles\/82423\/revisions\/82425"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/media\/27944"}],"wp:attachment":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/media?parent=82423"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/categories?post=82423"},{"taxonomy":"segments","embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/segments?post=82423"},{"taxonomy":"mercados","embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/mercados?post=82423"},{"taxonomy":"etapas","embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/etapas?post=82423"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}