/basics/index.html Discover Docker: Validation of your Docker environment Docker container Docker images Docker network Docker volumes Docker cleanup Alternative Image Builds Hugo en-US Mon, 01 Jan 0001 00:00:00 +0000 /basics/validation/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/validation/index.html Before starting the class, let’s make sure if things are up and running as they should. Prerequisites Make sure you are logged in to your attendee VM or any other valid Docker environment. Exercise - Help and Options Open your terminal application and run the plain docker command in order to display a generic help message and available options: docker Exercise - Version To get some information about the version of your Docker installation run: /basics/container/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/container/index.html Exercise - List container and images In order to look up whether you have any containers, execute the following command: docker container ls As you have just started with the lab, the list of containers is empty. $ docker container ls CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES Info docker container ls and docker ps are identical commands In order to check whether you already have any local images, execute the following command: /basics/images/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/images/index.html Exercise - Build your image using commit (Optional) To recap the essentials from the Container Exercises run a container in detached mode, using port mapping, environment variables and a custom name (base_container): docker run -d -p 8080:8080 -e PROPERTY=Stuttgart --name base_container novatec/technologyconsulting-hello-container:v0.1 Milestone: DOCKER/IMAGES/BUILD-COMMIT and validate if the container is doing what it is supposed to do: curl localhost:8080/hello; echo Hello World (from 34f40588f2e0) to Stuttgart Containers are basically isolated processes. To find out more about this execute the ps command in the following way: /basics/network/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/network/index.html Exercise - Network introduction As a result of the “Images” exercise you can now see the following containers in your list: docker ps $ docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES b2a968f4f4b0 postgres:latest "docker-entrypoint.s…" 6 minutes ago Up 6 minutes 0.0.0.0:5432->5432/tcp, :::5432->5432/tcp postgresdb d266fc71ab06 todoui:v0.1 "/__cacert_entrypoin…" 8 minutes ago Up 8 minutes 0.0.0.0:8090->8090/tcp, :::8090->8090/tcp todoui 265da979af36 todobackend:v0.1 "/__cacert_entrypoin…" 12 minutes ago Up 12 minutes 0.0.0.0:8080->8080/tcp, :::8080->8080/tcp todobackend If you pick the backend container and execute a shell, you will be able to find out that there is no connection between the instances. /basics/volumes/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/volumes/index.html Data Persistence Without Volumes In this chapter we are going to take a look at how to persist data with docker. First we want to observe how data behaves in docker containers with the setup we have so far and no additional steps taken towards data persistence. Subtask 1: Create a PostgreSQL Container without Volumes Let’s start removing the old and creating a new database. While the previously created database is working fine, we want to illustrate the differences between starting a database with and without volume more clearly. Therefore, remove the old database first by running docker rm -f postgresdb. /basics/cleanup/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/cleanup/index.html Exercise - Clean up You will not need the running containers after this, so clean up the environment before proceeding: To stop all running containers execute: docker ps -q | xargs docker stop To remove all containers run: docker ps -a -q | xargs docker rm The network we created also still exists: docker network ls NETWORK ID NAME DRIVER SCOPE 10b9448cc71d bridge bridge local 2d2089ec09bd host host local 81e8bb2089d0 none null local 3ba6a91f405b todonet bridge local To remove the network use: /basics/build/index.html Mon, 01 Jan 0001 00:00:00 +0000 /basics/build/index.html About This lab will walk you through steps to build container images with various technologies. Validation Validate Java installation. java --version Should display output like (version might differ): openjdk 17.0.9 2023-10-17 OpenJDK Runtime Environment (build 17.0.9+9-Ubuntu-120.04) OpenJDK 64-Bit Server VM (build 17.0.9+9-Ubuntu-120.04, mixed mode, sharing) Dockerfile Exercises In this part of the exercise multiple options to use Dockerfiles will be shown and applied.