12-Factor App with Docker

Ophélie Mauger Consultante DevOps - Alter Way

Why twelve-factor app ?● Maximum portability between environments

● Suitable for deployment on modern cloud platforms

● Scale up

● Minimize time and costs with automation

● Continuous deployment

Why docker can help ?● Maximum portability between environments

● Suitable for deployment on modern cloud platforms

● Scale up

● Minimize time and costs with automation

● Continuous deployment

12 factor App with docker step by step

codebase dependencies config backing services

build, release, runprocesses

port binding concurrency

disposability dev/prod parity Logs

Admin processes

I. CodeBase

One codebase tracked in revision control

II. Dependencies

Explicitly declare & isolate dependencies

|||. Config

Store config in the environment

● Linux environment variables

● docker-compose can define env variables via env files

IV. Backing services

Treat backing services as attached

ressources

● Linux environment variables

● docker-compose can define env variables via env files

● docker allows you to link services together

V. Build, Release, Run

Strictly separate build and run stages

● docker build --pull -t sampleapi:1.0 .

● docker push sampleapi:1.0

● docker run sampleapi:1.0

VI. Processes

Execute the app as one or more stateless

processes

● docker enforces stateless processes

● Use volumes to persist data

Export services via port binding

VII. Port Binding

Docker Host

service network

container http

container php-fpm

container mysql

port binding

VIII. Concurrency

Scale out via the process model

Docker Cluster

docker host docker host docker host

http php

worker worker

worker worker

http php

worker worker

worker worker

http php

worker worker

worker worker

Workload divercity

scale

IX. Disposability

Maximize robustness with fast startup and

graceful shutdown

● Container restart policies

● Orchestration with docker swarm

● Reverse proxy and load balancing with

services containers

X. Dev/Prod parity

Keep development, staging, and

production as similar as possible

● “build once, run anywhere”

● Same app images across DevOps stages

XI. Logs

Treat logs as event streams

Dev environment

Logs in container stdout

>docker logs -f …>docker-compose logs -f

Ops environment

Log driver : fluentd

container fluentd

XII. Admin processes

Run Admin/management tasks as one of

processes

docker exec ….

And what about continuous deployment ?

Continuous Delivery with DockerBuild stage :

● docker build --pull -t myregistry/myimage:$version

● docker push myregistry/myimage:$version

Continuous Deployment with dockerDeploy stage :

● Connect to the swarm (export DOCKER_HOST, ...)

● docker-compose pull

● docker-compose up -d

ConclusionIf you plan to do a twelve-factor app

use docker to make it