Suse Academic Introduction to containers

Playing with CLI

• Check you have installed docker or podman:

podman run hello-world

docker run hello-world

• Run a container:

podman run -d --name mynginx nginx

docker run -d --name mynginx nginx

• List the containers running:

podman ps

docker ps

• Enter a running container:

podman exec -ti mynginx bash

docker exec -ti mynginx bash

• Check a container's logs:

podman logs mynginx

docker logs mynginx

• Inspect a container's data:

podman inspect mynginx

docker inspect mynginx

• Check a container's running processes:

podman top mynginx

docker top mynginx

• Check container's resources consumption:

podman stats mynginx

docker stats mynginx

• Pause a running container:

podman pause mynginx

docker pause mynginx

• Unpause a container:

podman unpause mynginx

docker unpause mynginx

• Stop a container:

podman stop mynginx

docker stop mynginx

• Start a container:

podman start mynginx

docker start mynginx

• kill a container:

podman kill mynginx

docker kill mynginx

• delete a container:

podman delete mynginx

docker delete mynginx

Let’s explore a bit the filesystem

• Remove all containers:

podman rm -f $(podman ps -aq)

docker rm -f $(docker ps -aq)

• Get a alpine image:

podman pull alpine

docker pull alpine

• Check layers of a image:

podman history alpine

docker history alpine

• Lunch a alpine and attach to it:

podman run --name mytest --ti alpine bash

docker run --name mytest --ti alpine bash

Inside the container (mytest):

echo "Hi" > myfile
rm /etc/localtime

Check the diff

podman diff mytest

docker diff mytest

Create a new image with the changes:

podman commit mytest academy/mytest:r0

docker commit mytest academy/mytest:r0

Check the history of the new image:

podman history academy/mytest:r0

docker history academy/mytest:r0

Export a image:

podman save academy/mytest:ro -o /tmp/image.tar

docker save academy/mytest:ro -o /tmp/image.tar

Image registry:

podman search wordpress

docker search wordpress

podman search wordpress --list-tags

Configuring containers

podman run --name mymaria -d -e MARIADB_ROOT_PASSWORD="pa$$w0rd" -e MARIADB_USER="foo" -e MARIADB_PASSWORD="bar1234" -e MARIADB_DATABASE="academy" docker.io/library/mariadb

docker run --name mymaria -d -e MARIADB_ROOT_PASSWORD="pa$$w0rd" -e MARIADB_USER="foo" -e MARIADB_PASSWORD="bar1234" -e MARIADB_DATABASE="academy" mariadb

Using Networks

podman run --name client --rm -ti docker.io/library/mysql:latest bash

docker run --name client --rm -ti mysql bash

In the console of the container:

mysql -h "mymaria" -u"foo" -p"bar1234" "academy"

You can't access so let's use a networks:

podman network create testnetwork
podman network inspect testnetwork

docker network create testnetwork
docker network inspect testnetwork

Now try to access again:

podman run --name mymaria --hostname mymaria --network testnetwork -d -e MARIADB_ROOT_PASSWORD="pa$$w0rd" -e MARIADB_USER="foo" -e MARIADB_PASSWORD="bar1234" -e MARIADB_DATABASE="academy" mariadb

podman run --name client --network testnetwork -ti --rm docker.io/library/mysql:latest bash

docker run --name mymaria --hostname mymaria --network testnetwork -d -e MARIADB_ROOT_PASSWORD="pa$$w0rd" -e MARIADB_USER="foo" -e MARIADB_PASSWORD="bar1234" -e MARIADB_DATABASE="academy" mariadb

docker run --name client --network testnetwork --rm -ti mysql bash

mysql -h "mymaria" -u"foo" -p"bar1234" "academy"

Port publishing

podman ps -a
podman stop mymaria && docker rm mymaria

podman run --name mymaria -p 3306:3306 --hostname mymaria --network testnetwork -d -e MARIADB_ROOT_PASSWORD="pa$$w0rd" -e MARIADB_USER="foo" -e MARIADB_PASSWORD="bar1234" -e MARIADB_DATABASE="academy" mariadb

docker ps -a
docker stop mymaria && docker rm mymaria

docker run --name mymaria -p 3306:3306 --hostname mymaria --network testnetwork -d -e MARIADB_ROOT_PASSWORD="pa$$w0rd" -e MARIADB_USER="foo" -e MARIADB_PASSWORD="bar1234" -e MARIADB_DATABASE="academy" mariadb

Working with volumes

podman volume create myvol
podman volume inspect myvol

podman run --name cont1 -v myvol:/mnt/volume -ti alpine
podman run --name cont2 -v myvol:/mnt/volume -ti alpine

docker volume create myvol
docker volume inspect myvol

docker run --name cont1 -v myvol:/mnt/volume -ti alpine
docker run --name cont2 -v myvol:/mnt/volume -ti alpine

MariaDB with persistence

podman stop $(podman ps -aq) && podman rm $(podman ps -aq)

docker stop $(docker ps -aq) && docker rm $(docker ps -aq)

Create a new volume

podman volume create mariadb-data

docker volume create mariadb-data

Deploy a new container with the volume

podman run -d -p 3306:3306 --name mymaria \
  --hostname mymaria \
  --network testnetwork \
  -e MARIADB_ROOT_PASSWORD="pa$$w0rd" \
  -e MARIADB_USER="foo" \
  -e MARIADB_PASSWORD="bar123" \
  -e MARIADB_DATABASE="academy" \
  -v mariadb_data:/var/lib/mysql mariadb

docker run -d -p 3306:3306 --name mymaria \
  --hostname mymaria \
  --network testnetwork \
  -e MARIADB_ROOT_PASSWORD="pa$$w0rd" \
  -e MARIADB_USER="foo" \
  -e MARIADB_PASSWORD="bar123" \
  -e MARIADB_DATABASE="academy" \
  -v mariadb_data:/var/lib/mysql mariadb

You can specify a path in your host:

podman run -d -p 3306:3306 --name maria2 \
  --hostname mymaria \
  --network testnetwork \
  -e MARIADB_ROOT_PASSWORD="pa$$w0rd" \
  -e MARIADB_USER="foo" \
  -e MARIADB_PASSWORD="bar1234" \
  -e MARIADB_DATABASE="academy" \
  -v /tmp/mypath:/var/lib/mysql mariadb

docker run -d -p 3306:3306 --name maria2 \
  --hostname mymaria \
  --network testnetwork \
  -e MARIADB_ROOT_PASSWORD="pa$$w0rd" \
  -e MARIADB_USER="foo" \
  -e MARIADB_PASSWORD="bar1234" \
  -e MARIADB_DATABASE="academy" \
  -v /tmp/mypath:/var/lib/mysql mariadb

Dockerfile

podman build -t academy/test:latest .
podman run -d --name test  -p 8080:80 academy/test:latest

docker build -t academy/test:latest .
docker run -d --name test  -p 8080:80 academy/test:latest

Tips for not running out of space

podman container prune
podman image prune
podman volume prune
podman system prune

docker container prune
docker image prune
docker volume prune
docker system prune

Docker Compose

docker run -d --name mymongo mongo

version: '3'
services:
  mongodb:
    image: mongo
    container_name: mymongo

docker compose up -d

docker compose down

docker compose -f docker-compose-mariadb.yaml up -d

Testing docker-compose:

mariadb -h "mariadb" -u"foo" -p"bar1234" "academy"

Some docker compose commands

docker compose ps
docker compose stop client
docker compose run client bash
docker compose run --no-deps client bash
docker compose logs
docker compose down --volumes