DockerCon 2023 Getting Started Workshop

This repository contains my answers for the various challenges I completed during the Getting Started with Docker Workshop

Pre-Requisites

You need Docker Desktop installed and the following extension Click this link

Completing the Challenges

Running Containers

In this part, the main goal is to understand basic docker commands

1. docker run --name hello-world hello-world
2. docker run -it --name timer -rm ubuntu sleep 30
3. docker run -d -p 80:8080 --name nginx nginx:alpine
4. docker run -d --label training.app=mysql -e MYSQL_ROOT_PASSWORD=secret -e MYSQL_DATABASE=app mysql
5. docker run -d -p 5050:5000 --label training.app=cats --health-cmd="curl -f http://localhost:5000/healthcheck" --health-interval=5s mikesir87/cats:1.0

Main takeways:

• image name often comes last and the : allows you to pick specific image versions
• docker -> all docker commands starts with docker(!)
• run -> starts/runs a docker image
• --name -> sets the name of the container to be created
• -it -> iteractive mode; after running it, your terminal is positioned inside the container
• -d -> detached mode; terminal is not bound to the container
• -p -> X:Y;exposes port X on the host port Y
• --label -> key-pair values
• -e -> setts env variables
• --health-cmd -> checks availability of the application
• --heath-interval -> how often should it be health-cheacked

Working with Volumes

Here we can learn about how the command -v works

1. docker volume create database-files docker volume create volume1
2. docker run -d --label training.app=persistent-db -v mysql-files:/var/lib/mysql mysql:latest
3. docker run -it --name init-db -e MYSQL_DATABASE=db -e MYSQL_ROOT_PASSWORD=secret -v "$(pwd)/database-initialization:/docker-entrypoint-initdb.d" mysql
4. docker run -it -v "$(pwd)/dev-express:/app" -p 3000:3000 -w /app --name node-app --rm node:lts-alpine yarn dev

Main takeaways:

• The default command upon initializing a container is replaced by whatever is after the image name
• -v (volume) -> bind mount a volume; basically copies content from one folder to another one inside the container
• $(pwd) -> specify the path to the dev-express folder relative to current working directory
• -w -> sets container working directory

Building images

This section covers Dockerfile usage, therefore most of the answers are inside the Dockerfiles

1. docker build -t first-build .
2. docker build -t simple-python-webapp .
3. docker build -t nonroot-node-app
4. docker build -t multi-stage-react-app

Key takeways:

• Dockerfile is basically a file that configures multiple commands that will be executed in order
• To create another stage, use FROM img:version AS stageName
• --chown -> sets file/folder owner
• Most used instructions: FROM, WORKDIR, COPY, RUN, EXPOSE, CMD

Multi-service applications

Get in touch with docker compose

1. docker network create getting-started
2. docker run --name networked-db -e MYSQL_ROOT_PASSWORD=pwd -e MYSQL_DATABASE=db --network getting-started --network-alias db mysql
3. docker network create wordpress

docker run -d --network wordpress --network-alias db -e MYSQL_ROOT_PASSWORD=secret -e MYSQL_DATABASE=wordpress mysql

docker run -d --network wordpress -e WORDPRESS_DB_HOST=db -e WORDPRESS_DB_USER=root -e WORDPRESS_DB_PASSWORD=secret wordpress:6-apache

4. see multi-deploy-compose folder

docker compose up

5. see compose-project folder

while trying to target the dev stage Ive encountered some issues that this question on stackoverflow helped solve https://stackoverflow.com/questions/69042916/docker-compose-does-not-start-the-specified-stage

Basically what I had to do was to run docker build before docker compose up, after that I managed to validate my answer and finish the workshop.

Key takeaways:

• Docker commands can be translated to compose files
• Use "target" section to pick between Dockerfile stages
• --network -> place container in specific network so it can communicate with other apps
• Each image have their own env variable and should be checked in their own docs
• Ports and volumes are supposed to be represented as lists
• Add network section to an app's compose file to mimic -network parameter

Need help?

• View the Slides to refresh your memory
• Join the Docker Community Slack and hop into the #dockercon23-getting-started-workshop channel