Building and Deploying Apps with Docker!

12:30 pm - 2:30 pm 6th July, 2024

Hi, I am Milind

  • 8+ years  in building large scale ecommerce.
  • Checkout, Payments, Promotions & Integrations
  • Java/Spring, PHP and JavaScript/Node.js
  • commercetools, Magento/Adobe Commerce, Shopify and Hybris/SAP Commerce.

Operating System

  • an interface between user and hardware
  • manages resources like memory, cpu, files and devices
  • networking, security and process management

Linux

  • Linux® is an open source operating system (OS).
  • Kernel: The base component of the OS.
  • System user space: The administrative layer for system-level tasks like configuration and software install.  shell, daemons, processes and the desktop environment.
  • Applications: Apps include everything from desktop tools and programming languages to multiuser business suites.

Linux Kernel

Linux Container

Namespace

Control Group

A Linux® container is a set of 1 or more processes that are isolated from the rest of the system.

 Linux kernel feature that partition kernel resources such that one set of processes sees one set of resources, while another set of processes sees a different set of resources.

It allows you to allocate resources such as CPU time, system memory, network bandwidth, etc, so that an activity per service instance can be ran and constrained by cgroups on the system.

Exercise 1

# CLI to List system namespaces.
lsns --help

# list all ns
lsns

Virtualization vs Containers

Docker 

Docker is an open platform for developing, shipping, and running containerized applications.

Why Docker ?

  • Solves the “works on my machine” problem.
  • Rapid CI/CD
  • Easy Auto Scaling. GCP Cloud Run, Azure Functions, AWS ECS

Installing Docker

# 1. Set up Docker's apt repository.

# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

# Add the repository to Apt sources:
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

# 2. Install the Docker packages.
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# Docker Service Start
sudo service docker start

# Verify that the Docker Engine installation is successful by running the hello-world image.
sudo docker run hello-world


WSL 2

Exercise 2:  Running a Docker Container

# download an docker image, eg nginx
docker pull nginx

# run image, use -d to run in background
docker run --name exercise2 -p 8080:80 nginx

# check in browser
http://localhost:8080/

# check docker running process
docker ps

# stop
docker stop exercise2

# restart
docker start exercise2

# check logs
docker logs exercise2

# Get PID for docker container
docker inspect --format '{{.State.Pid}}' exercise2

# List docker container ns
sudo ls -la /proc/7059/ns

Building a Docker Container: Dockerfile

A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.

ADD	Add local or remote files and directories.
ARG	Use build-time variables.
CMD	Specify default commands.
COPY	Copy files and directories.
ENTRYPOINT	Specify default executable.
ENV	Set environment variables.
EXPOSE	Describe which ports your application is listening on.
FROM	Create a new build stage from a base image.
HEALTHCHECK	Check a container's health on startup.
LABEL	Add metadata to an image.
MAINTAINER	Specify the author of an image.
ONBUILD	Specify instructions for when the image is used in a build.
RUN	Execute build commands.
SHELL	Set the default shell of an image.
STOPSIGNAL	Specify the system call signal for exiting a container.
USER	Set user and group ID.
VOLUME	Create volume mounts.
WORKDIR	Change working directory.

Exercise 3: Dockerize a Node.js API

# Build a docker container
docker build -t node-api --no-cache .

# Run a docker container
docker run -p 3000:3000 node-api

# Remove image
docker rmi node-api --force

# Clear cache!
docker system prune -a
# Dockerfile

FROM node:22-alpine

RUN mkdir -p /home/node/app/node_modules && chown -R node:node /home/node/app

WORKDIR /home/node/app

COPY package*.json ./

USER node

RUN npm install

COPY --chown=node:node . .

EXPOSE 3000

ENTRYPOINT [ "node", "index.js" ]

Exercise 4: Storing a Container Image

  1. Register at Google Cloud and Setup Billing.
  2. Create 'Artifact Registry' repository.
  3. Setup Google Cloud CLI on Local.
  4. Run below commands to push an image
gcloud config set project milindsingh

gcloud auth login

gcloud auth configure-docker asia-south2-docker.pkg.dev

docker build -t asia-south2-docker.pkg.dev/milindsingh/docker-meetup/node-api:2024.07.06.1 .

docker push asia-south2-docker.pkg.dev/milindsingh/docker-meetup/node-api:2024.07.06.1

Exercise 5: Deploying Containerized App on Google Cloud

  1. Register on Google Cloud and Setup Billing.
  2. Create new service in 'Cloud Run'
  3. Choose container created in previous exercise.
  4. Select region and set port as 3000.
  5. Create and test url.

Docker Compose

Docker Compose is a tool for defining and running multi-container applications.

# compose.yaml

services:
  nginx:
    image: "nginx"
    ports:
      - "80:80"
      
  node:
  	image: "node"
    
  redis:
    image: "redis:alpine"

Exercise 5: Running multiple containers

References

Thank You

Docker Lucknow Meetup - 6 July 2024

By Milind Singh

Docker Lucknow Meetup - 6 July 2024

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