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7-docker

README.md

Docker

Docekr basic commands their flags

Command Description Flags/Options
docker run Run a new container -d (detached), -p (port mapping), --name (name of the container), -e (environment variables)
docker ps List running containers -a (all containers), --format (format output)
docker stop Stop a running container <container_id/name> (ID or name of the container)
docker rm Remove a container -f (force), <container_id/name>
docker images List Docker images -a (all images), --format (format output)
docker rmi Remove a Docker image <image_id/name> (ID or name of the image), -f (force)
docker build Build an image from a Dockerfile -t (tag/name of the image), <path_to_Dockerfile>
docker pull Pull an image from a registry <image_name> (name of the image)
docker push Push an image to a registry <image_name> (name of the image)
docker exec Execute a command in a running container -it (interactive terminal), <container_id/name> (ID or name of the container), <command> (command to execute)
docker logs Fetch the logs of a container <container_id/name> (ID or name of the container), --tail (number of lines to show)
docker network Manage Docker networks create, inspect, ls, rm (subcommands for network management)
docker volume Manage Docker volumes create, inspect, ls, rm (subcommands for volume management)

Lesson 7 Demo 2

Performing CRUD Operation on Containers

Steps to be followed:

  1. Pulling a Docker image
  2. Creating a new container
  3. Stopping the container
  4. Listing all the containers
  5. Deleting the container
  6. Removing the image

Step 1: Pulling a Docker image

1.1 Open the terminal and pull an image using the command:

sudo docker pull nginx

1.2 List all the docker images to check the newly pulled nginx image:

sudo docker images

Step 2: Creating a new container

2.1 Create a new container from the nginx image:

sudo docker run -dt -p 81:81 nginx

2.2 List all the running containers to check the newly created container. You can find various details like port of container, it’s time of creation and ID.

sudo docker ps

Step 3: Stopping the container

3.1 Use the following command to stop the running container. (You can also us the container ID to stop the container:

sudo docker stop CONTAINER_ID)


sudo docker stop CONTAINER_NAME

3.2 Use the following command to list all the running containers and verify if the container has stopped running:

sudo docker ps

3.3 You can start the container again and check the running containers. (You can also us the container ID to start the container:

sudo docker start CONTAINER_ID)


sudo docker start CONTAINER_NAME

sudo docker ps

3.4 To start the container in interactive mode, use the –i and –t options.

sudo docker run -it --name=Test_1 ubuntu

Step 4: Listing all the containers

4.1 Use the below command to list all the containers started and the once which are stopped:

sudo docker ps -a

4.2 To list the containers by their ID, use the below command

sudo docker ps -aq

You can see the containers with ID are listed.

4.3 To list the total file size of each container, use the below command:

sudo docker ps -s

4.4 To list the latest created containers, use the following command:

sudo docker ps -l

Step 5: Deleting the container

5.1 Stop the running container and remove it using the following commands:

sudo docker stop CONTAINER_NAME
sudo docker container rm CONTAINER_NAME

Step 6: Removing the image

6.1 Remove the image using the command:

sudo docker image rm nginx

Lesson 7 Demo 3

Creating a Docker Image

Steps to be followed:

  1. Creating the Dockerfile
  2. Executing the Dockerfile

Step 1: Creating the Dockerfile

1.1 Create a directory

mkdir demo
cd demo

1.2 Create the Dockerfile

vi Dockerfile

1.3 Add the following code snippet to the Dockerfile

# Use Ubuntu as a base image
FROM ubuntu

# Update and install nginx
RUN apt-get update && apt-get install -y nginx

# Copy the custom index file to the nginx directory
COPY index.html /var/www/html

# Start nginx in the foreground to keep the container running
CMD ["nginx", "-g", "daemon off;"]

1.4 Create another file in the same directory

vi index.html

1.5 Add the following welcome message to the index file

WELCOME TO NGINX.

Step 2: Executing the file

  • 2.1 Execute the Dockerfile (note that there is space between build and “.”)
sudo docker build .

2.2 Navigate to the root folder, and list the images to check the newly created Docker image

cd
sudo docker images

Lesson 7 Demo 4

Docker Compose Setup

Steps to be followed:

  1. Setting up docker-compose
  2. Creating a docker-compose file

Step 1: Setting up docker-compose

1.1 Install docker-compose using the command given below:

mkdir compose-test
cd compose-test
pip --version

1.2 Then type the command given below, to install docker-compose

sudo pip install docker-compose

Step 2: Creating docker-compose file

2.1 Inside compose-test folder, create docker-compose.yml file, and add the following code in it:

vi docker-compose.yml

2.2 Add the following code snippet in the file:

version: '3'
services:
  compose-test:
    image: centos
    command: /bin/bash -c "while true; do sleep 30; done"
    depends_on:
      - compose-db
  compose-db:
    image: redis
    ports:
      - "6379:6379"

  • In this updated version, I've added version: '3' at the top. This is the version of the Docker Compose file format, and it's generally a good idea to specify it.

  • I also replaced links with depends_on, which makes sure the compose-db service is started before the compose-test service.

  • I've replaced the command for the compose-test service to keep the container running indefinitely. Your previous command would execute curl once and then the container would exit. If you need to run curl, you can do it manually by exec-ing into the running container.

  • Finally, expose only exposes the port to linked services; it doesn't map the port to the host. If you want to access the Redis service from outside of the Docker network (from your host machine, for example), you should use ports instead. If not, you can stick with expose.

2.3 Run the following command to execute the yaml file:

sudo docker-compose up

Lesson 7 Demo 5

Docker Registry

Steps to be followed:

  1. Pulling a Linux container
  2. Pushing the image to the local repository
  3. Running the new image

Step 1: Pulling a Linux container

1.1 Pull a recent version of the Centos Linux container.

sudo docker pull registry:2

1.2 Run the registry in a new Docker container with port 5000 exposed

sudo docker run -d -p 5000:5000 \
--restart=always --name registry registry:2

1.3 Pull another image from Docker Hub and store it in the local registry

sudo docker pull ubuntu

1.4 Tag the image for the local registry

sudo docker tag ubuntu localhost:5000/ubuntu

Step 2: Pushing the image to the local registry

2.1 Use the following command to push the image to a local registry:

sudo docker push localhost:5000/ubuntu

2.2 Remove the image from the local cache

sudo docker rmi ubuntu

2.3 Confirm that it has been removed

sudo docker images

Step 3: Running the new image

3.1 Pull the image from the local registry

sudo docker pull localhost:5000/ubuntu

3.2 Confirm it is in the local cache

sudo docker images

3.3 Run the new image

sudo docker run -it --rm localhost:5000/ubuntu /bin/bash

3.4 Exit the container


exit

3.5 Clean up the images and containers

sudo docker rm -f $(docker ps -aq)

Note: In case you get a permission denied error as shown below, run the following

sudo chmod 666 /var/run/docker.sock

After running this, run the

sudo docker rm -f $(docker ps -aq) command.
 

sudo docker rmi $(docker images -q)

Lesson 7 Demo 6

Docker Networking with SSHs

Steps to be followed:

  1. Creating a container and committing it
  2. Creating a bridge network and finding its IP address
  3. Connecting the network from another SSH server

Step 1: Creating a container, and commit it

1.1 Create a Centos Docker container. and install net-tools

sudo docker run -it --name centos centos /bin/bash
yum install -y net-tools

1.2 Check the IP address and hostname

ifconfig
cat /etc/hosts
hostname

1.3 Exit the container using CTRL+D 1.3.1 Commit the container to an image (Please refer to the screenshot)

	docker commit centos centos-net
	docker images
	docker rm centos

Step 2: Creating a bridge network, and find its IP address

2.1 Create a bridge network, and find its IP range

docker network create exnet
docker network ls
docker network inspect exnet

2.2 Run the centos container using the new network

docker run -it --rm --network exnet centos-net /bin/bash

2.3 Check the IP address and hostname

ifconfig
cat /etc/hosts
hostname

2.4 Exit the container using CTRL+D 2.4.1 Start a new container using the default network

	docker run -it --rm --name centos centos-net /bin/bash

2.5 Check the IP address and hostname

ifconfig
cat /etc/hosts
hostname

Step 3: Connecting the network from another SSH server

3.1 Click on + to open another Terminal window. Type the below given command to from the second SSH terminal to connect the network to the container

docker network connect exnet centos

3.2 Go back to the running container. You will see that it now has two IP addresses (Please refer to the screenshot)

ifconfig
cat /etc/hosts
hostname

3.3 Go to the second SSH window, and disconnect the network

docker network disconnect exnet centos

3.4 Go back to the running container, and see that it now has one IP address

ifconfig
cat /etc/hosts
hostname

3.5 Exit the container using CTRL+D