Day-2

These steps should give you an understanding of checking 

if Docker is installed, 

installing it if necessary, 

starting the Docker service,

 pulling and running the "Hello World" image, 

and checking the images and container status on your CentOS instance

1. To check if Docker is installed, run the command:

```bash

docker --version

```

Output (if Docker is not installed):

```

bash: docker: command not found

```

2. Install Docker using `yum`:

```bash

sudo yum update

sudo yum install -y docker

```

Output:

```

[...]

Complete!

```

3. Start the Docker service:

```bash

sudo systemctl start docker

```

Output (no output indicates successful execution):

4. Enable Docker to start on system boot:

```bash

sudo systemctl enable docker

```

Output (no output indicates successful execution):

5. Check the Docker version again:

```bash

docker --version

```

Output (example):

```

Docker version 20.10.7, build f0df350

```

6. List the Docker images available:

```bash

sudo docker images

```

Output (if Docker is just installed and no images have been pulled yet):

```

REPOSITORY   TAG       IMAGE ID       CREATED      SIZE

```

7. Run the "Hello World" Docker image:

```bash

sudo docker run hello-world

```

Output (example):

```

Hello from Docker!

This message shows that your installation appears to be working correctly.

[...]

```

8. List the Docker images again:

```bash

sudo docker images

```

Output (after running the "Hello World" image):

```

REPOSITORY   TAG       IMAGE ID       CREATED        SIZE

hello-world  latest    fce289e99eb9   7 months ago   13.3kB

```

9. List the running containers:

```bash

sudo docker ps

```

Output (if no containers are running):

```

CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

```

10. List all containers (including stopped containers):

```bash

sudo docker ps -a

```

Output (after running the "Hello World" image):

```

CONTAINER ID   IMAGE         COMMAND       CREATED          STATUS                      PORTS     NAMES

eef4b5f60df9   hello-world   "/hello"      2 minutes ago    Exited (0) 2 minutes ago              hungry_wescoff

```

11. Run the "Hello World" image again:

```bash

sudo docker run hello-world

```

Output (example):

```

Hello from Docker!

This message shows that your installation appears to be working correctly.

[...]

```

docker run --name , docker serach, docker pull, docker tag, docker login, docker push

1. Run the "Hello World" Docker image with the container name `C1`:

```bash

sudo docker run --name C1 hello-world

```

Output:

```

Hello from Docker!

This message shows that your installation appears to be working correctly.

[...]

```

This command creates and runs a container named `C1` from the "Hello World" image.

2. List the Docker images available:

```bash

docker images

```

Output (example):

```

REPOSITORY   TAG       IMAGE ID       CREATED        SIZE

hello-world  latest    fce289e99eb9   7 months ago   13.3kB

```

This command lists the Docker images currently available on your system.

3. Search for the Ubuntu image on Docker Hub:

```bash

sudo docker search ubuntu

```

Output (example):

```

NAME              DESCRIPTION             STARS    OFFICIAL   AUTOMATED

ubuntu            Ubuntu is a Debian-b...  13127    [OK]

[...]

```

This command searches for the Ubuntu image on Docker Hub and displays a list of related images.

4. Pull the Ubuntu image from Docker Hub:

```bash

docker pull ubuntu

```

Output (example):

```

Using default tag: latest

latest: Pulling from library/ubuntu

[...]

```

This command downloads the latest version of the Ubuntu image from Docker Hub to your local system.

5. Difference between `pull` and `run` commands:

   - `docker pull` is used to download Docker images from a registry (such as Docker Hub) to your local system. It retrieves the image and stores it locally, making it available for future use.

   - `docker run` is used to create and run a container from a Docker image. It pulls the image if it is not already available locally and starts a new container based on that image.

6. Pull a specific version (tag) of a custom image:

```bash

docker pull devopstrainer/myimage:4

```

Output (example):

```

Using default tag: latest

latest: Pulling from devopstrainer/myimage

[...]

```

This command pulls the version `4` of a custom image named `devopstrainer/myimage` from Docker Hub.

7. List the Docker images available:

```bash

docker images

```

Output (example):

```

REPOSITORY                 TAG       IMAGE ID       CREATED        SIZE

hello-world                latest    fce289e99eb9   7 months ago   13.3kB

ubuntu                     latest    1318b700e415   7 months ago   72.7MB

devopstrainer/myimage      4         b39ea256c708   12 months ago  450MB

```

This command lists the Docker images available on your system, including the ones you pulled.

8. Tag an existing image with a new name and version:

```bash

sudo docker tag devopstrainer/myimage:4 devopstrainer/myimage:5

```

Output (no output indicates successful execution):

This command creates a new tag (`5`) for the existing image `devopstrainer/myimage:4`.

9. Push the tagged image to a Docker registry:

```bash

sudo docker push devopstrainer/myimage:5

```

Output (example):

```

The push refers to repository [docker.io/devopstrainer/myimage]

[...]

```

This command pushes the tagged image `devopstrainer/myimage:5` to a Docker registry, such as Docker Hub.

10. Login to a Docker registry:

```bash

docker login <username>

```

Replace `<username>` with your Docker Hub username or the appropriate registry. You will be prompted to enter your password.

11. View the Docker configuration file:

```bash

sudo cat /root/.docker/config.json

```

Output (example):

```

{

  "auths": {

    "https://index.docker.io/v1/": {

      "auth": "<base64-encoded-authentication-details>"

    }

  }

}

```

This command displays the contents of the Docker configuration file that stores the authentication details for Docker registries.

12. Push the tagged image to a Docker registry after logging in:

```bash

sudo docker push devopstrainer/myimage:5

```

Output (example):

```

The push refers to repository [docker.io/devopstrainer/myimage]

[...]

```

This command pushes the tagged image `devopstrainer/myimage:5` to a Docker registry after logging in.

docker run -itd, docker stop, docker run -it, docker start, docker attach, docker stats

1. Run an Ubuntu container in detached mode:

```bash

docker run -itd ubuntu

```

Output (example):

```

c6c6a3fba661f35ad4d4a5080619c028a66edc0a648b6c1821695e9fe98dbb32

```

This command creates and starts a new Ubuntu container in detached mode. The container ID is displayed as the output.

2. List the running containers:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS         PORTS   NAMES

c6c6a3fba661   ubuntu   "/bin/bash"   2 minutes ago   Up 2 minutes          zen_archimedes

```

This command lists the currently running containers, including the newly created Ubuntu container.

3. Stop a running container:

```bash

docker stop zen_archimedes

```

Output (no output indicates successful execution):

This command stops the container with the name `zen_archimedes`.

4. List the running containers again:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED      STATUS        PORTS   NAMES

```

This command displays an empty list since the previously running container has been stopped.

5. List all containers (including stopped containers):

```bash

docker ps -a

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS                      PORTS   NAMES

c6c6a3fba661   ubuntu   "/bin/bash"   10 minutes ago   Exited (0) 2 minutes ago          zen_archimedes

```

This command lists all containers, including the stopped container `zen_archimedes`.

6. Difference between `run` and `start` commands:

   - `docker run` creates and starts a new container from an image. It is used to create and start a container in one step.

   - `docker start` starts one or more stopped containers. It is used to restart a container that was previously created.

7. Run an interactive Ubuntu container:

```bash

docker run -it ubuntu

```

Output:

```

root@39a88861c09e:/#

```

This command starts a new interactive session inside an Ubuntu container, allowing you to execute commands within the container.

8. Check for the `yum` package manager inside the container:

```bash

yum

```

Output (example):

```

bash: yum: command not found

```

The `yum` package manager is not available in Ubuntu, so it returns a "command not found" error.

9. Check for the `apt-get` package manager inside the container:

```bash

apt-get

```

Output (example):

```

bash: apt-get: command not found

```

The `apt-get` package manager is available in Ubuntu and returns a "command not found" error only if the package is not installed.

10. Exit the interactive session:

```bash

exit

```

Output (no output indicates successful execution):

This command exits the interactive session inside the container and returns you to the host machine's terminal.

11. List all containers (including stopped containers):

```bash

docker ps -a

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED        STATUS                      PORTS   NAMES

39a88861c09e   ubuntu   "/bin/bash"   2 minutes ago   Exited (0) 20 seconds ago          thirsty_davinci

```

This command displays the stopped container `thirsty_davinci`.

12. Run an interactive Ubuntu container again:

```bash

docker run -it ubuntu

```

Output:

```

root@ca7987d7c124:/#

```

This command starts a new interactive session inside another Ubuntu container.

13. Detach from the interactive session using keyboard shortcuts:

Press `Ctrl+p` followed by `Ctrl+q`.

Output (no output indicates successful execution):

This command detaches the interactive session without stopping the container.

14. List the running containers:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS         PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   2 minutes ago   Up 2 minutes          musing_curie

```

This command shows the running container `musing_curie`.

15. Stop a running container:

```bash

docker stop musing_curie

```

Output (no output indicates successful execution):

This command stops the container `musing_curie`.

16. List all containers (including stopped containers):

```bash

docker ps -a

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS                      PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   6 minutes ago   Exited (0) 3 seconds ago           musing_curie

```

This command displays the stopped container `musing_curie`.

17. Start a stopped container:

```bash

docker start musing_curie

```

Output (no output indicates successful execution):

This command starts the stopped container `musing_curie`.

18. List the running containers:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED          STATUS         PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   6 minutes ago    Up 3 seconds          musing_curie

```

This command shows the running container `musing_curie`.

19. Attach to a running container:

```bash

docker attach musing_curie

```

Output:

```

root@ca7987d7c124:/#

```

This command attaches to the running container `musing_curie` and provides an interactive session inside the container.

20. Difference between `docker attach` and `docker run -it`:

   - `docker attach` attaches the host's standard input, output, and error streams to a running container, allowing you to interact with the container's terminal.

   - `docker run -it` starts a new container and provides an interactive session with a terminal.

21. List the running containers:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS          PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   10 minutes ago   Up 2 minutes           musing_curie

```

This command shows the running container `musing_curie`.

22. List all containers (including stopped containers):

```bash

docker ps -a

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS                      PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   10 minutes ago   Exited (0) 1 second ago           musing_curie

```

This command displays the stopped container `musing_curie`.

23. Detach from the interactive session using keyboard shortcuts:

Press `Ctrl+p` followed by `Ctrl+q`.

Output (no output indicates successful execution

):

This command detaches the interactive session without stopping the container.

24. Display resource usage statistics of running containers:

```bash

docker stats

```

Output (example):

```

CONTAINER ID   NAME            CPU %     MEM USAGE / LIMIT     MEM %     NET I/O       BLOCK I/O     PIDS

ca7987d7c124   musing_curie    0.00%     3.898MiB / 7.632GiB   0.05%     648B / 648B   0B / 0B       1

```

This command displays real-time statistics for the running container(s), including CPU usage, memory usage, network I/O, block I/O, and process ID statistics.

25. Suspend the current Docker command:

Press `Ctrl+z`.

Output (example):

```

[1]+  Stopped                 docker stats

```

This command suspends the current Docker command and returns you to the host machine's terminal.

26. List the running containers:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED        STATUS                      PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   13 minutes ago   Up 4 minutes                       musing_curie

```

This command shows the running container `musing_curie`.

docker rm, docker rm -f, docker rmi

1. List the running containers:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED        STATUS         PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   10 minutes ago   Up 4 minutes          musing_curie

```

This command lists the currently running containers.

2. Remove a container by its name:

```bash

docker rm musing_curie

```

Output (example):

```

musing_curie

```

This command removes the container with the name `musing_curie`.

3. Forcefully remove a running container:

```bash

docker rm -f musing_curie

```

Output (example):

```

musing_curie

```

This command forcefully removes the running container with the name `musing_curie`.

4. List the running containers again:

```bash

docker ps

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS         PORTS   NAMES

```

This command shows an empty list since the previously running container has been removed.

5. List the Docker images available:

```bash

docker images

```

Output (example):

```

REPOSITORY   TAG       IMAGE ID       CREATED        SIZE

ubuntu       latest    1318b700e415   7 months ago   72.7MB

hello-world  latest    fce289e99eb9   7 months ago   13.3kB

```

This command lists the Docker images available on your system.

6. Remove an image:

```bash

docker rmi ubuntu

```

Output (example):

```

Untagged: ubuntu:latest

Deleted: sha256:1318b700e4154643f20de8ab4747b329ac0b54e87dcb24d62cb82e8b42a67114

Deleted: sha256:631ceee03dceb948f93a9b3316a313ee55e1d7cf30835a3d496f34b6aa6c7f65

```

This command removes the Ubuntu image.

7. Remove an image:

```bash

docker rmi hello-world

```

Output (example):

```

Untagged: hello-world:latest

Deleted: sha256:fce289e99eb9a84ed5af6b23b1a50fe16f32b3cbed6487b9daf18e8bcaf67d2f

```

This command removes the "Hello World" image.

8. List the Docker images again:

```bash

docker images

```

Output (example):

```

REPOSITORY   TAG       IMAGE ID       CREATED        SIZE

```

This command shows an empty list since both the Ubuntu and "Hello World" images have been removed.

9. List all containers (including stopped containers):

```bash

docker ps -a

```

Output (example):

```

CONTAINER ID   IMAGE    COMMAND   CREATED         STATUS                      PORTS   NAMES

ca7987d7c124   ubuntu   "/bin/bash"   20 minutes ago   Exited (0) 10 minutes ago          musing_curie

```

This command lists all containers, including the previously removed container `musing_curie`.

To create an Amazon Elastic Container Registry (ECR) repository named "repo1" using the AWS Management Console, follow these steps:

1. Open the AWS Management Console in your web browser and log in to your AWS account.

2. Navigate to the Amazon ECR service by searching for "ECR" in the AWS services search bar and selecting "Amazon Elastic Container Registry."

3. In the ECR console, click on the "Repositories" tab on the left-hand side.

4. Click on the "Create repository" button.

5. In the "Create repository" dialog box, provide the following details:

   - Repository name: Enter "repo1" as the name for your repository.

   - Tag immutability: Choose whether you want the tags on the images to be mutable or immutable.

   - Image scan setting: Specify whether you want images to be scanned for vulnerabilities.

   - Encryption: Choose whether you want the repository to be encrypted at rest using Amazon ECR managed keys or a custom key.

   - Lifecycle policy: If needed, configure a lifecycle policy to manage image lifecycle.

6. After providing the necessary information, click on the "Create repository" button.

7. The ECR repository named "repo1" will be created, and you will be redirected to the repository details page.

8. From the repository details page, you can find the repository URI, ARN, and other information related to the repository.

9. You can now use this repository to push and pull Docker images using the provided repository URI.

By following these steps in the AWS Management Console, you can create an ECR repository named "repo1" and manage your container images within it.