containwd.pdf

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1. CONTAINERIZE YOUR APP WITH DOCKER Naga Sowjanya Mudunuri Senior Software Engineer, Heroku @gritncompassion
2. References • http://www.linfo.org/ • https://docs.docker.com/ @gritncompassion
3. Acknowledgements • Ricardo Chimal • Bernerd Schaefer @gritncompassion
4. Agenda • Background on how containers work • Overview of Docker • Docker containers, images & persistence • Hands-on practice • Multi container applications with docker-compose @gritncompassion
5. OS Kernel vs User processes Kernel: • Is the first part of OS that is loaded into memory during system boot • Manages IPC and process management ( Manages hardware directly ) • Manages I/O, Memory • Interacts with underlying hardware User processes: • Interacts with Kernel using system calls (Manages hardware through the kernel) • Runs in the Userspace of the system @gritncompassion
6. Container • Runs as a User process • replicate consistent environments for dev/staging/prod • easier to scale your app horizontally • run on any OS @gritncompassion
7. What is docker? • Is a software which enables you to package an app and its dependencies together into an image • You can run multiple containers on the same machine and share the same kernel, each running an isolated process in the user space • cross-platform support for Mac, Windows, Linux @gritncompassion
8. @gritncompassion Reference:: https://docs.docker.com/get-started/#containers-and-virtual-machines
9. Workflow: Deploy a ruby on rails app In the past: • You downloaded ruby on your machine • You downloaded rails on your the machine • Make an app • Assume the machine you are deploying to, also has the same ruby version and rails version installed and then you can deploy a working app @gritncompassion
10. Workflow: Deploy a ruby on rails app Now: • Get the docker image with ruby and rails installed with host OS • Create a new image with your app and the original image and deploy the new image @gritncompassion
11. Docker images • Binary executable composed of the app and its dependencies based on Dockerfile • Docker images are made of layers Useful commands: • docker image ls • docker container ls –all @gritncompassion
12. Dockerfile • Defines the components that will make up your new image for the app • FROM: • sets the base image for subsequent instructions; • a Dockerfile starts with a FROM instruction • Can appear multiple times within a single Dockerfile to create multiple images • ARG: to declare variables • WORKDIR: specifies the working directory for the subsequent RUN, CMD, COPY and ADD that follow it • ENV: is used to setup environment variables @gritncompassion
13. Dockerfile • RUN: executes commands and outputs a new layer on top of an existing image and as a result creates a new image • EXPOSE: Specifies to the Docker Daemon that container listens on the specified port • CMD: Execute the command; only one per dockerfile • COPY: copies files, directories from src and adds them to the filesystem of the image @gritncompassion
14. Dockerfile (EXPOSE) • https://docs.docker.com/engine/reference/builder/#expose • Publish all exposed ports(tcp/udp): docker run -P • port redirection: docker run –p ip:hostport:containerport • docker run –p 8000:80 • docker port <container> @gritncompassion
15. Port Mapping in Docker @gritncompassion
16. Sample Dockerfile @gritncompassion
17. Most used docker commands • docker –version • docker ps à list all running containers • docker ps –a à list all running and stopped containers • docker images • docker container –help • start • stop • rm • kill • ls • docker image –help • docker ports <container_name> @gritncompassion
18. Building and running images • docker build –t <Image_name> . • docker run –it <images> /bin/bash • docker run -p 3000:3000 <image> @gritncompassion
19. Practice • Go App • https://github.com/sowjumn/go-docker-test • Ruby App • https://github.com/sowjumn/ruby-docker-test • Node App • https://github.com/sowjumn/node-docker-test @gritncompassion
20. Practice • Go to those apps and clone them (whichever language you are most comfortable in) • Build your docker image and run them • Try to Curl and see what you get • docker ps and look at the port mappings • docker stop to stop a container • docker start to start a container @gritncompassion
21. Data Persistence: Volumes • Save & Read data from host machine by the container • Volumes : • managed by docker • can be created and managed outside the scope of a container • Mounts: • dependent on the directory structure of the host machine @gritncompassion
22. Data Persistence: Practice • docker volume create test-volume • docker volume inspect test-volume • docker volume ls • docker volume prune @gritncompassion
23. Docker compose • Run multi container docker applications • docker-compose.yml • describe the services for your app • docker-compose build • docker-compose up • docker-compose config @gritncompassion
24. Docker compose • docker-compose run web rake db:create • docker-compose run web rake db:migrate • docker-compose up • docker-compose down @gritncompassion
25. Practice: docker-compose •https://github.com/sowjumn/rails-dc-compose-test •Clone this and try to spin up the app using the commands in Readme.md @gritncompassion
26. THANK YOU! @gritncompassion