The software development industry has one of the fastest growth rates among business sectors. With a CAGR of 5.27%, the software market is projected to reach US$ 858.10bn by 2028.This rapid growth of the software industry is driven by modern digitisation and the Internet of Things. To keep up with the growing demand for software production, multiple techniques, like DevOps, have been introduced to make the software production lifecycle more efficient. By combining and improving collaboration between the development and operations teams, DevOps has revolutionised the software development industry. However, various tools and technologies, such as cloud services and concepts like containerization, have significantly contributed to the success of DevOps.Therefore, tools like Docker, which allows IT professionals and software developers to separate applications from the infrastructure for quicker software delivery, are in high demand. Leveraging such platforms can help you stay ahead of the competition.About DockerAn open-source containerization platform that helps develop, run, and ship applications, Docker can be used by developers to package and run any software in an isolated environment, known as a container.Running an application in a container allows independence from infrastructure. Therefore, the software deployed can run on any host computer or server without needing any specialised installation. This helps improve collaboration and standardisation during the software development procedure.Docker ContainersDocker containers are essentially a code unit that includes everything an application requires to run. This consists of the code and its dependencies, such as system tools, system libraries, runtime environment, and settings. Moreover, since containers share the host operating system kernel, they are lighter than virtual machines. Containers can be built locally and added to a container registry, from where they can be deployed to any infrastructure. This helps support the principles of DevOps by enabling automated application deployment. Docker ArchitectureDocker uses a client-server architecture where the Docker client talks to the Docker daemon which carries out the tasks for building and running containers. A Docker architecture consists of the following key parts:ImagesA read-only template that contains instructions to help create a Docker container, a Docker image is built from Dockerfiles. These images can be shared via Docker registries like Docker Hub. Docker ClientThe Docker client is the mode of communication between Docker users and the platform for commands. Docker DaemonThe Docker Daemon receives the commands from the Docker client and performs the building, running, and distributing of the Docker containers. ContainersA container is a runtime instance of the image and helps run the application in an isolated environment. DockerfileThis is a text document that contains instructions to build the Docker image. This includes command sets and arguments that can be used to auto-generate the image.Docker HubThis is a public registry in the form of a SaaS service provided by Docker to help share and manage Docker images. Docker EnginePowering the Docker platform, a Docker Engine consists of the Daemon, a CLI, and a REST API. Application of Docker In DevOpsDocker is an open-source tool that can benefit both Developers and IT Operation team, therefore forming an integral part of DevOps toolchains. Docker can be applied in the following ways:Continuous IntegrationDocker helps ensure continuous integration pipelines as containers can help automate the deployment of software and applications. In addition, it allows developers to build, package, and test their applications in isolated environments, which can be further used for creating other software. Continuous DeploymentDocker also provides multiple tools for efficient packaging and deployment of containerized applications to production environments consistently. TestingContainers provide an ideal environment for running automated tests as they are isolated and standardised. Infrastructure As CodeIaC is a vital principle of DevOps and developers can leverage Docker as an essential IaC tool for supplementing DevOps key strategies. AutomationThe biggest benefit of using Docker containers is the automation of tasks such as testing, deployment, and integration of codes into a common repository. This helps save time, energy, and costs and improves the efficiency of software production. Monitoring And LoggingDocker containers also help generate metrics that can be analysed and monitored to gain insights into application performance for further updates. Benefits of Docker In DevOpsDocker, as an open-source platform, enables developers to pack and run an application in an isolated environment. In addition, it has multiple tools and an all-inclusive platform that aids the management of the lifecycle of containers, also helping with the following:Develop the application and its supporting components using containersEasy distribution and testing of applications within the containersQuick deployment of the application in different environments The following are the benefits of using Docker in DevOps:Consistent DeploymentsThe container-based approach of Docker enables you to create automated development and deployment workflows. For example, when you create an update for software, Docker can automatically rebuild the container, run tests, and release the new version. This aligned with the continuous integration and deployment principles of DevOps. Standardisation Of EnvironmentSince Docker containers carry all the configuration and dependencies required for running the application, it helps run the application regardless of the environment. As a result, you don’t need any environment-specific configuration to manage the application. This also helps reduce errors related to environmental inconsistencies. PortabilitySince docker images and containers are completely portable, you can build your applications locally and deploy them to the cloud, enabling you to run them anywhere. ScalabilityDocker-based applications can also be easily scaled up or down by adding or removing containers. This also provides greater flexibility and quicker response to changes in the demand. IsolationWith the self-running capability of Docker containers containing their own CPU, memory, filesystem, network interfaces, and process space, you can run multiple containers on a single host. Install Docker on an Ubuntu systemUpdate Your Packages#Update Packages sudo apt-get updateInstall Required Packagessudo apt-get install \ ca-certificates \ curl \ gnupg \ lsb-releaseAdd Docker’s Official GPG Keysudo mkdir -p /etc/apt/keyrings curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpgSet Up the Stable Repositoryecho \ "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \ $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/nullUpdate the APT Packagesudo apt-get updateInstall Docker Engine, Docker CLI, Containers, and Docker Composesudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-pluginVerify Docker Installationsudo docker run hello-worldIntegrating Docker with JenkinsStep 1: Install Docker on the Jenkins Serversudo apt-get update sudo apt-get install docker.io sudo usermod -aG docker jenkinsStep 2: Install Docker Plugin in JenkinsSearch for and install the "Docker Pipeline"Step 3: Configure Docker in JenkinsGo to Manage Jenkins Configure SystemNow Under the Cloud Section Add new 'Docker Cloud'Configure unix:///var/run/docker.sockStep 4: Create a Jenkins Pipelinepipeline { agent { docker { image 'maven:3.6.3-jdk-8' } } stages { stage('Build') { steps { sh 'mvn clean package' } } } }Step 5: Run the Pipelinepipeline { agent any environment { DOCKER_IMAGE = 'maven:3.6.3-jdk-8' } stages { stage('Build') { steps { script { docker.image(DOCKER_IMAGE).inside { sh 'mvn clean package' } } } } } }Useful Commands for DockerFunctionalityCommandDescriptionDocker Version & Infodocker versionShow the Docker version information docker infoDisplay system-wide informationContainer Managementdocker psList running containers docker ps -aList all containers (running and stopped) docker run <image>Run a new container from an image docker run -d <image>Run a container in detached mode docker run -it <image>Run a container in interactive mode with a terminal docker exec -it <container-id> <command>Run a command in a running container docker stop <container-id>Stop a running container docker start <container-id>Start a stopped container docker restart <container-id>Restart a container docker rm <container-id>Remove a container docker rm $(docker ps -a -q)Remove all stopped containersImage Managementdocker imagesList all images docker pull <image>Pull an image from a registry docker build -t <image-name> <path>Build an image from a Dockerfile docker tag <image> <repository>/<image>:<tag>Tag an image with a repository and tag docker push <repository>/<image>:<tag>Push an image to a registry docker rmi <image>Remove an image docker rmi $(docker images -q)Remove all imagesVolume Managementdocker volume lsList all volumes docker volume create <volume-name>Create a new volume docker volume rm <volume-name>Remove a volume docker volume rm $(docker volume ls -q)Remove all volumesNetwork Managementdocker network lsList all networks docker network create <network-name>Create a new network docker network rm <network-name>Remove a network docker network rm $(docker network ls -q)Remove all networksDocker Composedocker-compose upCreate and start containers defined in docker-compose.yml docker-compose up -dStart containers in detached mode docker-compose downStop and remove containers, networks, volumes, and images docker-compose psList containers defined in docker-compose.yml docker-compose logsView logs of containers docker-compose buildBuild or rebuild services docker-compose pullPull service images docker-compose exec <service> <command>Execute a command in a running service containerContainer Logsdocker logs <container-id>View logs of a container docker logs -f <container-id>Follow the logs of a containerInspect & Statsdocker inspect <container-id>Return low-level information on Docker objects docker statsDisplay a live stream of container resource usage statisticsExport & Importdocker save -o <file> <image>Save an image to a tar archive docker load -i <file>Load an image from a tar archive docker export <container-id> -o <file>Export a container’s filesystem as a tar archive docker import <file>Import the contents from a tarball to create a filesystem imageConclusionThe Docker platform can prove to be an essential tool for any DevOps-based software production lifecycle. With multiple tools and services that facilitate efficient workflows, Docker helps boost productivity. It helps ensure a standard environment, provides security, and improves the scalability of a project. Moreover, Docker addresses different challenges faced by the DevOps team during the optimization of the application lifecycle. The use of Docker can open up different possibilities for creating scalable, automated workflows to help build and release applications.Read Morehttps://devopsden.io/article/is-heroku-a-devops-toolFollow us onhttps://www.linkedin.com/company/devopsden/
