Docker Introduction
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Docker is a technology that uses lightweight containers to package applications and their dependencies in a standardized way. This allows applications to be easily deployed across different environments without changes to the installation procedure. Docker simplifies DevOps tasks by enabling a "build once, ship anywhere" model through standardized environments and images. Key benefits include faster deployments, increased utilization of resources, and easier integration with continuous delivery and cloud platforms.
Docker Introduction
- 2. Classic Deployments Several environments Dev Test QA Production Common problems: Environments not equal to each other (OS, hardware, software versions) Resources not utilized Different installation procedures for each environment www.sparkbit.pl
- 3. Docker Overview • Lightweight containers • Share OS with host (only user space is separate) • Can be started in seconds • One container = one application • One system can be built with many containers • Stateless containers • Storage containers • Can be wired together by using docker-compose www.sparkbit.pl
- 4. Docker Architecture • Docker container is an application with all of its dependencies • Compared to traditional VM: • No Hypervisor • No Guest OS • Containers are isolated www.sparkbit.pl
- 5. Docker Dictionary • Image – read only snapshot used to build a container • Container – runtime environment built using an image • Dockerfile – recipe on how to create an image • Registry – public or private service for storing images • DockerHub https://hub.docker.com/ - official public registry, like GitHub for docker images www.sparkbit.pl
- 6. Dockerfile • Sample app: https://github.com/tkopczynski/spring-boot-docker • Application should be run by a single command • Application should run on linux • Dockerfile: FROM java:8 # Define base image ADD target/spring-boot-docker.jar spring-boot-docker.jar # Copy application into the image CMD java –jar /spring-boot-docker.jar # Execute application www.sparkbit.pl
- 7. Predefined Images • DockerHub offers predefined images with many well-known applications • docker run -–name mysql –e MYSQL_ROOT_PASSWORD=root –d –p 3306:3306 mysql • mysql –u root –p –H 127.0.0.1 –P 3306 • docker run –-name solr –d –p 8983:8983 –t solr • http://localhost:8983 • And many, many more... www.sparkbit.pl
- 8. Docker Use Cases • Integration with continuous delivery process • Automatically building images and pushing them to the registry • Standardized environments • Application doesn’t require anything outside of the container so it is always executed in the same environment • Microservices architecture • Manage all microservices as docker images regardless of their technologies and dependencies • Scaling • It is possible to automatically spin up new containers during traffic volume peaks www.sparkbit.pl
- 9. Docker in Continuous Delivery • After commiting to version control, CI server builds an image with the new version of the application • Container based on that image is tested • If tests pass, it is deployed to test, QA and production environments with the same installation procedure www.sparkbit.pl
- 10. Docker in Continuous Delivery www.sparkbit.pl
- 11. Docker in The Cloud • Some of the providers: • Amazon EC2 Container Service • Google Container Engine (based on Kubernetes) • Tutum • Docker VM Extension in Azure www.sparkbit.pl
- 12. Summary • Docker is a technology aimed at simplifying DevOps tasks • Build once, ship and run anywhere principle • Lightweight containers • Easily integrated with continuous delivery process and cloud infrastructure www.sparkbit.pl