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Docker Demo

Container Usages

Lab details

- Pull container image form Docker Hub

  • Pulling a NGINX container image without specifying a tag. Docker will pull the image with latest tag.

    docker image pull nginx

  • Pull container image with a specific tag by adding : after the image name followed by a tag name.

    docker image pull nginx:1.21

- Pull container image from other registries

  • Pulling an Open JDK 8 container image from quay.io.

    docker image pull quay.io/public/openjdk:8-slim

- Get list of container images

  • Get list of container images on the host.

    docker image ls

- Run a container with container image in local

  • Run a container with the image you just pulled above.

    docker container run nginx:1.21

  • Press Ctrl + C on keyboard to stop and exit from the container.

- Run a container without container image in local

  • Run a container without pulling container image.

    docker container run httpd

  • Press Ctrl + C on keyboard to stop and exit from the container.

Run a container in detatch mode

  • Run NGINX container in detatch mode by adding -d flag. The container will be running in background like daemon processes.

    docker container run -d --name nginx-daemon nginx

    Docker will print out only container ID and you won't see any output or logs.

  • Use following command to check if the container is running.

    docker container ls

- Get list of containers

  • Get list of running containers.

    docker container ps

  • Get list of all containers regardless of their statuses.

    docker container ps -a

- Attach to a container running in detatch mode

  • Run an Ubuntu container in detatch mode (-d) and name the container (--name) as ubuntu-date and override its default command (bash) with an inline while loop that will be printing current date and time every second.

    docker run -d --name ubuntu-date ubuntu sh -c 'while true; do date; sleep 1; done'

    Docker will print out only container ID and you won't see date and time get printed out because the container will be running as a background process.

  • Attach local standard input, output, and error (your terminal) to the container.

    docker container attach ubuntu-date

    You'll see date and time get printed out for every second.

  • Press Ctrl + C on keyboard to stop and exit from the container.

- Execute command inside a container from host

  • First, run a container in detatch mode.

    docker container run -d --name mynginx nginx:1.21

  • Run env command inside mynginx container.

    docker container exec mynginx env

- Inspect a container

You can inspect the details of any container to see its details i.e. Network, Mount, Configurations and so on.

  • Inspect mynginx container you ran earlier to see its details.

    docker container inspect mynginx

- Inspect inside a running container

  • Get an interactive terminal for mynginx container.

    docker container exec -it mynginx /bin/sh

  • Use ls command to explore filesystem inside the container.

  • Type exit and press enter to exit. This will just exit from the Shell process and won't stop the main process of the container, NGINX, in this case.

- Inspect container logs

  • Get all logs from mynginx container.

    docker container logs mynginx

  • Keep following logs from mynginx container.

    docker container logs -f mynginx

  • Press Ctrl + C on keyboard to exit and return back to terminal.

- Start, Stop, and Delete an existing container

  • First, get list of all containers.

    docker container ls -a

  • Start a stopped container. Any container has been stopped can be started again. For example, using follwing command to start the ubuntu-date container you ran earlier.

    docker container start ubuntu-date

  • Stop a running container. Use following command to stop myginx container you ran earlier.

    docker container stop mynginx

  • Stop multiple running containers. Use following command to stop ubuntu-date and nginx-daemon containers you ran earlier.

    docker container stop ubuntu-date nginx-daemon

  • Verify that there isn't any container running.

    docker container ls

  • Delete a container. Use following command to delete mynginx container.

    docker container rm mynginx

  • Verify that all containers are stopped e.g. the status is Exited.

    docker container ls -a

  • Delete all stopped containers using this command. Enter 'y' to confirm deletion.

    docker container prune

  • Verify that all containers have been removed.

    docker container ls -a

Container Storage

Lab details

- Docker Volume: named-volume

  • Run a container with a named-volume by adding -v flag followed by volume name and path inside the container.

    docker container run -e POSTGRES_USER=postgres -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=testdb -v pgdata:/var/lib/postgresql/data --name postgresdb2 -d postgres

  • Inspect the container to get volume information using the command below. Then look for "Mounts" section. You will see mount type, volume name, and its location.

    docker container inspect postgresdb2

  • Verify that the pgdata volume gets created.

    docker volume ls

  • (Optional) Use ls command to explore data inside the volume.

- Docker Bind mount

  • Run a container and mount mypgdata directory to the container with bind mount.

    docker run -d -e POSTGRES_USER=postgres -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=testdb -v $HOME/mypgdata:/var/lib/postgresql/data --name postgresdb3 postgres

  • Inspect the container to get volume information using the command below. Then look for "Mounts" section. You will see mount type, volume name, and its location.

    docker container inspect postgresdb3

  • Verify that mypgdata volume didn't get created.

    docker volume ls

  • Use ls command to explore data inside the $HOME/mypgdata directory.

    ls $HOME/mypgdata

Container Network

Lab details

- Forward traffic from host's network to containers in bridge network

  • Run a container with bridge network mode and add port forwarding by adding -p 8080:80 flag so port 8080 on the host is mapped to port 80 of the container.

    docker container run -d --network bridge -p 8080:80 --name nginx2 nginx

  • Use curl command to verify that the container running in the private bridge network with port forwarding now can be accessed from the host's network.

    curl http://localhost:8080

  • Inspect the container to get IP address using the command below. Then look for IPAddress in the "Networks" section.

    docker container inspect nginx2

  • Run a new container in the same bridge network and execute wget command to verify that the containers within the same bridge network can access to each other.

    docker container run --network bridge busybox wget -S -O- http://<nginx2 container IP address>

Container Image

Lab details

- Building container image

  • Clone a project from GitHub.

    git clone https://github.com/audomsak/node-express-website

  • Enter to the node-express-website directory.

    cd node-express-website

  • View Dockerfile details.

    cat Dockerfile

  • Build a new container image and specify repository and tag by adding : after the repository name and followed by a tag name.

    docker image build -t rhworkshop/node-website:1.0 .

  • Get list of images to verify that a new container image is built with the specified repository and tag.

    docker image ls

  • Run a container with the image you have just built.

    docker container run -d -p 1234:80 --name mywebsite rhworkshop/node-website:1.0

  • Use curl command to verify that you can access to the website running in the container.

    curl http://localhost:1234

- Tagging and versioning

  • Add a new tag for the existing container image to have multiple tags or versions.

    docker image tag rhworkshop/node-website:1.0 rhworkshop/node-website:release

  • Get list of container images to verify the new tag gets created.

    docker image ls

- Pushing container image to Docker Hub

  • Login to Docker hub with your Docker Hub username and password.

    docker login

  • Push the container image to Docker Hub

    docker image push rhworkshop/node-website:1.0
docker image push rhworkshop/node-website:latest

  • Go to Docker Hub website to verify the container image and tags.