Introduction to Docker

1. Docker Introduction
Tomasz Kopczynski
Sparkbit

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
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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
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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
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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
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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
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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...
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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
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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
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10. Docker in Continuous Delivery
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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
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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
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