CUNY Codes Fall 2017 Docker
Robby O'Connor
Created: 2017-09-25 Mon 19:39
Introduction
Hunter College CS Alum (Fall 2014)
CUNY Codes Alum (Spring 2016) and Peer Mentor
Infrastructure Engineer/Steering Committee Member for LibreHealth(http://librehealth.io)
I Really Love Docker – A LOT!
What is Docker
Docker is a way to run containerized applications.
What does this mean?
Isolated from all other processes, much like a virtual machine.
The isolation pertains to: process id, networking, interprocess communication (IPC), mounts, and unix timesharing system.
The isolation mechanism is called namespaces. Another feature which is used is called control groups, or cgroups.
cgroups allow you to limit resource usage.
A container is not real thing, it's what the namespaces and cgroups when pulled together form.
Overview of Docker
Fundamentally different from Virtual Machines
Images
Networks
Volumes
Getting Docker
Docker provides support for Windows/Mac/Linux. though relies heavily on features embedded in the Linux Kernel to work.
Windows
Download Docker For Windows: https://docs.docker.com/docker-for-windows/install/
Mac
Download Docker For Mac: https://docs.docker.com/docker-for-mac/install/
Linux
For linux, using Ubuntu is probably the best: https://docs.docker.com/engine/installation/linux/ubuntu/
Our first Dockerfile (building our first Image)
What is an Image
An image is a set of instructions, which form immutable layers.
FROM node:8-alpine LABEL maintainer "Robby O'Connor <robby.oconnor@gmail.com>" CMD ["yarn","start"] WORKDIR /app RUN apk add --no-cache bash curl openssl git build-base gosu yarn \ --repository http://dl-3.alpinelinux.org/alpine/edge/testing/ \ --repository http://dl-3.alpinelinux.org/alpine/edge/community/ COPY docker/build.sh / RUN bash /build.sh COPY . /app ~ ~ ~ ~ ~ ~ ~ ~
Where's the database and why do I care about Docker at all?
Less bootstrap time
One environment for everything!
Overview on Docker Compose
A tool to orchastrate containers. You will have a container per process.
Example: Your app will run in one, MySQL in another, and whatever other service you need.
Docker Compose files are specified using a language called YAML.
version: "2.1" services: web: user: "${UID-1000}:${GID-1000}" build: context: . ports: - 0.0.0.0:3000:3000 depends_on: mongodb: condition: service_healthy volumes: - .:/app restart: unless-stopped container_name: "app" mongodb: image: mongo:3.4 ports: - "0.0.0.0:27017:27017" container_name: "_mongo" volumes: - ./data/mongo/db:/data/db healthcheck: test: ["CMD", "mongo", "--quiet", "localhost/test", "--eval","'quit(db.runCommand({ ping: 1 }).ok ? 0 : 1)';"] interval: 1m30s timeout: 10s retries: 3 restart: unless-stopped command: "mongod --nojournal --smallfiles" ~ ~ ~ ~ ~ ~ ~ ~