Questions to be Answered on Docker images

RajeshKumar1

1. List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.

2. What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.

3. How to Create a Docker Image Using a Container?

Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.

4. How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

5. Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.

6. How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

Kumar

RajeshKumar1

List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.
Answer:

docker images --> Used to see all the images availble in the localhost
docker exec -it "container name" --> attaches terminal to running container
docker inspect "container name" --> display's image configuration
docker logs "container name" --> displays logs of a container
docker stats "container name" --> displays cpu resources, memory usgae, i/o usage of a running contianer.
What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.
Answer:

It is nothing but a list of the applications. It contains root file system + user file system + app file system

How to Create a Docker Image Using a Container?

Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.

Answer:

Pull a latest image of an OS, here let's take Ubuntu for example.
Using the image create an container.
Start running container.
Enter into Container using docker exec -it "container name" /bin/bash
Download the required software,
1. before that we need to update list available softwares using apt-get update
2. Install required software
  a. apt-get install -y git
  b. apt-get install -y apache2
3. commit the container as new image using below command
  a. docker commit "container name" "name of the image":"version"
4. We can see the newly created image using command docker images.

How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.
Answer:

Create a docker file in a folder
Go to the folder path and open docker file
Add the list of the commands in the docker file, save the file and exit
run the below command to create image using docker file
docker build -t "image name":"version" . --> here . indicates the path of the dockerfile. As running command from the same path "." is mentioned. If we run from a different path then path of the file should be mentioned.
Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.
Answer:

FROM --> pulls base image which is required for building new image.
RUN --> Executes commands during build process
CMD --> specified default commands
ENV --> Set the enviornment variables
Copy --> Copying files from host to image
How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.
Answer:

Run the command docker login
Browser opens and ask for the Authentication
Once Authentication completed in browser same will get updated to terminal.
Chose the image which you want to upload to docker registry
run the command "docker push image name" which will push image to docker registry
while pushing repo name in docker registry and image name should be same.

RajaS

1. List of 5 Commands to Troubleshoot Docker Images
Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.
docker inspect -- used to check the low-leve information about image like metadata, layers, etc.
docker history -- check the layer details and the approach / commands used to create image
docker images -- to list the images created
docker logs -- to check the logs of container created out of image
docker exec -it for interactive debugging

2. What is Docker Image?
Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.
Docker image is a pre-defined template that holds the applications, libraries, dependencies, etc. to create container

3. How to Create a Docker Image Using a Container?
Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.
Docker image can be created using manual process OR Dockerfile
To create a image, we will need to create container with itd mode and then have required applications installed, for e.g. Java, apache2, etc. Execute docker commit command to create image and we can add tag as well. This approach will create image with combined layers
docker commit
docker tag

4. How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.
The approach can be used in automation mode to create image based on the configuration / steps laid out in Dockerfile. This method will create different image layer for each item in file. Dockerfile can have below keywords
FROM base package
RUN apt-get install packages
CMD bin/bash execution

5. Top 10 Instructions of Dockerfile
Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.
FROM base package
RUN apt-get install packages
CMD bin/bash execution
COPY to copy files and directories
ENV set the environment variable
EXPOSE create port mappings
LABEL add metadata
VOLUME create mounts
ARG pass variables
WORKDIR set working directory

6. How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.
docker build - to build the image
docker tag - tag with registry address to lookup
docker login - command to login the hub
docker push -- to push the build to registery

durgaA

List of 5 Commands to Troubleshoot Docker Images
docker images - it will provide the list of images
docker inspect image-id - it will provide the detailed information of image which is given in the command
docker history image-id - it will provide the history which is given in command
docker events - it will show the real time events
docker logs container-id - it will give the logs of the container

What is Docker Image?
Docker Image is an application. Image will contains the Root fs and user fs and application fs.

How to Create a Docker Image Using a Container?
1.create container from base image eg. ubuntu
docker run -dit --name --container-name imagename
2.execute the conatiner
docker exec -it container-id /bin/bash
3.install required tools
apt-get install git -y
4.commit the created container to image
docker commit -m message container-id image-name
5.verify the images and run the images
docker images
docker run -idt image-name

How to Create a Docker Image Using a Dockerfile?
1.create the new directory for dockerfile
2.create the docker file name dockerfile by using vi editor and enter the list of tools to be install inside the container and save.

build the image
docker build -t imagename:dockerfile
4.list the image
docker images
5.run the image
docker run -idt image-name
How to Upload Docker Images to a Docker Registry
1.login to registry
Do the authentication
3.Push the image
4.verify the push

SantoshKumar

List of 5 Commands to Troubleshoot Docker Images
docker history myimage
show the history
docker run -it myimage /bin/bash
It will create a container and allow us to open shell there.
docker inspect myimage
It shows all the internal details/configurations of the image in json format
docker diff containername
It shows the changes happeningin the container
docker logs containername
It shows the logs of the container
docker tag imagename taggedname
It is used to give a alias for the image

What is docker image?
Docker image contains root file system, user file system, and application file system.
First 2 is the base, application file system could be anything.

How to Create a Docker Image Using a Container?
If we have a container, lets say myubuntu, so to create an image we can run the following command
docker commit myubuntu myUbuntuV1
Where myUbuntuV1 is the new image

How to Create a Docker Image Using a Dockerfile
To create an image from the dockerfile using which we want to create an image,
there should be a file named dockerfile in the same directory and then we can run the
below command:-
docker build -t ubuntu-new-image:dockerfile
Now ubuntu-new-image will be created

Top 10 Instructions of Dockerfile
FROM ubuntu
This is used to tell what is the base image used to build this image.

COPY . /app
It tells that copy from hosting env to image

RUN apt-get update
It tells to update packages during build of the image

RUN apt-get install apache2
It tells to install papache2

CMD ["command"]
It tells that when container runs, what command need to be executed.

How to Upload Docker Images to a Docker Registry
It is the same concept as we do in case of git
docker push imagename url

ManuBhatnagar

List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.

docker logs <cid> --for checking log
docker inspect -- for image details and info
docker history <imge_name> -- for history
docker run -it <img_name> /bin/bash ---manually explore the filesystem

What is Docker Image?
A Docker image is a package that contains everything your app needs to run
Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.
A Docker image is a package that contains everything your app needs to run.

Mainly contains ( Root File structure - OS) + UserSpace (Dependecies n all -- .net framework, JRE etc) + Application space + Docker file etc.

How to Create a Docker Image Using a Container?
Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.
docker pull <image_name>
docker run -it --name myimage_name <image_name>
apt-get update
apt-get install -y git apache2
docker commit myimage_name ubuntu-git-apache2:v1

Verify Image----
docker images

How to Create a Docker Image Using a Dockerfile?
It involves set of instructions in a file .

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

Create a docker file in a directory
mkdir dockerFile
cd dockerFile
Open VI editor and paste the instructions need to create a image, Save the file

docker build command to create the image
docker build -t ubuntu-git-apache2:dockerFile

Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.
from --for the base image
run --exec during image build
cMD default command to run when a container starts.
env --environment variables inside the container.
entryPoint Configures a fixed executable to run; works well with CMD.

How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

docker login
Add passcode to link for lgin
tag it
docker tag local_img username/repository_name:tag
docker push username/repository_name:tag
Verify @dcker hub

RifaquatullahKhan

Ans1:
docker images List all images
docker images -a List all images, including intermediate layers
docker images --digests Show image encryption digests
docker images nginx List all images for the nginx repository
docker images -q Show only image IDs
Ans2:
Docker image is a blueprint container with root,user and app filesystem needed to run applications.
Ans3:
Steps
1. Pull the Ubuntu base image
docker pull ubuntu:latest
2. Run a container interactively
docker run -it --name myubuntu ubuntu:latest
3. Install git and apache2 inside the container
Inside the container shell:

	apt-get update
	apt-get install -y git apache2
	exit
4. Commit the container to a new image
	docker commit myubuntu ubuntu-git-apache2:v1
5. Verify the image
	docker images

6. Tag your image for clarity
	docker tag ubuntu-git-apache2:v1 myrepo/ubuntu-git-apache2:lab1
7. (Optional) Run a container from your new image
	docker run -it myrepo/ubuntu-git-apache2:lab1 bash

Ans4:
1. Create a new directory for your Dockerfile
mkdir dockerfile-lab
cd dockerfile-lab
2. Create the Dockerfile

Dockerfile

FROM ubuntu:latest

	RUN apt-get update && \
		apt-get install -y git apache2 && \
		apt-get clean

	CMD ["/bin/bash"]
Save this as Dockerfile.

3. Build the image
docker build -t ubuntu-git-apache2:dockerfile .
4. List the images
	docker images
5. Run the new image
	docker run -it ubuntu-git-apache2:dockerfile

Ans5:
FROM
CMD
RUN
USER
ENV
EXPOSE
WORKDIR
Ans6 :
1 save image
docker container commit c1234f943de rhel-httpd:latest
2 tag and push
docker image tag rhel-httpd:latest registry-host:5000/myadmin/rhel-httpd:latest
docker image push registry-host:5000/myadmin/rhel-httpd:latest

TanujSharma

List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.

a) docker inspect <image_id|name> - details / metadata about the image, details like tag, repo, ctime, et cetera
b) docker logs <name|id> - view logs of container, I/O errors/messages
c) docker history <name|id> - provides historical data about the image
d) docker info - provides information like docker root directory
e) docker images - provides list of images, related info
f) docker events - provides real time events

What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.

Docker image is collection of filesystems (rootfs + userfs + appfs)

rootfs - root file system -- provides base to install app
userfs - user file system -- provides user management
appfs - app file system -- where app files are stored (config, et cetera)

How to Create a Docker Image Using a Container?

Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.

Process is manual in nature
Steps -
a) Pull the image - docker pull <image_name>
b) Run container interactively - docker run -it --name <container_name> <image_name:version>
c) Step b will cause to login to container; inside which we need to run / install packages per requirement, along with installation of certain pre-requisites
d) commmit this container to new image - docker commit <container_name> <new_name:tag>
e) validate whether image got created - docker images
f) tag/alias for better understanding or if required for further distribution, push to other sources like dockerhub, et cetera

How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

Process is automated in nature
Steps -
a) create a local directory
b) change directory path to the one we just created
c) create dockerfile with set of commands / instructions and save
d) build the image - docker build -t <image_name:tag> .
e) validate whether image got created - docker images
f) run new image or upload to other sources as per requirement - docker run -it <image_nmae:tag>; uploading part will be written in answer for question no, 6

Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.
a) FROM - base image which will be used to build new one
b) RUN - run commands / sequences during build process with appropriate flags to avoid prompts that usually happend during manual install
c) MAINTAINER - Information (name, email) about the person who creates image
d) COPY - copies file or directory from host to image
e) CMD - command to be executed inside container
f) EXPOSE - to expose container to port number so specified
g) ENV - sets up environment variable
h) ADD - copies file or directory from host to image
i) VOLUME - volume to be created post container creation
j) USER - set username and UID

How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

Provied we have image ready as written under answers for questions, 3 and 4,

a) get docker hub public account created
b) create repository with appropriate name
c) issue git login command from the VM / cli, which will provide login code and link that can be used to authenticate over CLI - docker login
d) once step c is done, tag / alias image with name similar to the repo name on dockerhub - docker tag <local_image_name:tag> <repo_name>
e) validate whether image is tagged / name got changed - docker images
f) docker push <repo_name>
g) logout from dockerhub via cli - docker logout

likithadonta

List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.
docker images - to list the images
docker inspect [cont id] - give low level detailed information
docker history [cont id] - to show layers of the image or history of layers
dokcer run -it [cont id] bash - start a container to it's interactive bash
docker logs [cont id] - if the container statrts and failes can use this to read logs.

What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.

Ans - Docker image is template used to create containers, it has dependencies needed to run an app. [ installed packages, base os, app source code, docker instructions e.g. RUN, CMD, COPY)

How to Create a Docker Image Using a Container?
Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.
Answer -
docker run -it ubuntu [ a base image]run command in the container.
Inside the container shell-
apt-get update
apt-get install -y git apache2
exit

Commit the container to a new image - docker commit myubuntu ubuntu-git-apache2:v1

docker images to verify

How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

First make a directory, in that directory make editable file [ vi file], vi is editor*, then run the script of all according to the requirement, is the image requirement is ubuntu iage with git, apache and java.
Commit that docker file, Tag the created image.

Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.
FROM, RUN, CMF, COPY, ADD, ENV, EXPOSE, WORKDIR, ENTRYPOINT, VOLUME

How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

tag your image with your dockerhub username:
log in to docker hub:
docker login
docker push username
check on docker hub

likithadonta

List of 5 Commands to Troubleshoot Docker Images

What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.

Ans - Docker image is template used to create containers, it has dependencies needed to run an app. [ installed packages, base os, app source code, docker instructions e.g. RUN, CMD, COPY)

How to Create a Docker Image Using a Container?
Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.
Answer -
docker run -it ubuntu [ a base image]run command in the container.
Inside the container shell-
apt-get update
apt-get install -y git apache2
exit

Commit the container to a new image - docker commit myubuntu ubuntu-git-apache2:v1

docker images to verify

How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

Top 10 Instructions of Dockerfile

How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

tag your image with your dockerhub username:
log in to docker hub:
docker login
docker push username
check on docker hub

BalaTheresa

List of 5 Commands to Troubleshoot Docker Images
My Answer:
docker images: Lists all docker images on the system including repo name, tag and size
docker inspect <image-id>: Displays detailed information about a Docker image
docker history <ImageID>: shows the history of a Docker image including the icluding the commands used to build it.
docker run -it <image_id>: Runs Docker container from the image in an iterative mode.
docker run -itd <image_id>: Runs Docker container from the image in an iterative mode and dettaches
What is Docker Image?
My Answer:
Docker images are read-only templates that contain instructions for creating a container.
Docker Image Components:
Application code: The actual code of the application
Dependencies: Libraries, frameworks and other dependencies required by the application
Configurations: Configuration files and settings for the application
Runtime Environment: The environment in which the application will run
How to Create a Docker Image Using a Container?
My answer:
By using "Docker commit" command, we can create a new Docker image from an existing container.
Key Commands:
docker ps -a:Lists all containers including stopped ones.
docker commit <my_container_id> <my_new_image_name> -m <commit_message_to_the_image> -p <specifies_the_author_of_image>
How to Create a Docker Image Using a Dockerfile?My answer
My answer:
Steps:
Create a Dockerfile
Write Dockerfile instructions:
FROM:Specify base image
RUN:Execute commands during build process
COPY: copy files from host machine to the container
WORKDIR: set the working dir in the container
CMD:default command to run when container starts
Build the Docker Image: builds a docker image from a Dockerfile
Command:
docker build -t <image_name>
Top 10 Instructions of Dockerfile
My Answer:
FROM: Specify base image
RUN: Execute commands during build process
COPY: copy files from host machine to the container
WORKDIR: set the working dir in the container
CMD: default command to run when container starts
EXPOSE: exposes a port from the container to host machine ex: EXPOSE 80
ENV: sets Environment variables in the container
ADD: Copies files from host machine
How to Upload Docker Images to a Docker Registry
My Answer:
Create a Docker Hub Account: goto Docker hub and create an account
Login to Docker Hub: Use "docker login" command to login to the Docker Hub
Tag your Docker Image:
CMD: docker tag my_image:latest <your_user_name>/my_image:latest
Push the Docker Image:
CMD: docker push <your_user_name>/my_image:latest

pankajsharma

Ans 1Docker imageDocker build;docker run;docker tag;docker commit
Ans 2😃ocker image is run time application with code and dependencies.It help in tag ,loading ,saving and commit within docker ecosysytem..
Ans 3: to create docker image we need to do following
pull the base image>run the container in interactively >>install the git and apache-2 inside the container>commit the container to a new image >>verify the image.
key command include
docker pull; docker run -it -name cn:image; inside the shell run apt-get update and apt-get install -y git apache 2 exit;docker commit

Ans 4Create a new directory for the dockerfile after that create a dockerfile ,next is build the image ,list the image and run the image.
mkdir for creating directory,using cd enter the dir,after that create the docker file using vi command and enter the below line in the file
Run apt-get update &&\
apt -get install -y git apache 2 &&\
apt-get clean

CMD ["/bin/bash"]

docker build - t image:docker file
docker image
docker run -it image:docker file

ans 5
FROM >specify the base image for new image
RUN>command is used during image build process
COPY>copy file from host machine to the container and vice -versa
WORKDIR>set the working directory
EXPOSE>document which post to expose
CMD>provide default command for an executing container
Volume>to create external mount point
inspect>to check the entire config details
update>to update any value in the config like cpu

ArunSolairajan

List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.

docker inspect - provides detailed information of image
docker logs - provides the logs of image which can be used for identifying the errors/issue
docker stats - monitors the resource usage of image in real time
docker history - provides the history of image
docker image ls - lists the available images

What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.

Docker image is a package which consists of file, libraries and configurations required within container for a application.

How to Create a Docker Image Using a Container?

Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.

Pull the base/source image
Run the container interactively
docker run -it --name containername imagename
Install the required process inside container
apt-get update or apt-get install -y [software1] [software2]
Commit the container to new image
docker commit containername newimagename
Verify the image
docker images
How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

Create the docker file with required commands to be executed
vi Dockerfile -> save the file after including all the required commands
Build image
docker build -t imagename
List the image to confirm once before running it
docker images
Run the new image
docker run -it newimagename
Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.

FROM - Createsthe base image
RUN - Executes shell commands during build time
CMD - Provides default command to run at container start
ENTRYPOINT - Defines a fixed command, often combined with CMD for args
COPY - Copies files into the image
ADD - To add URLs and archives
ENV - To set environment variables
EXPOSE - Documents container listening to which port
WORKDIR - Sets the working directory for following instructions
VOLUME - Declares mount points for persistent or shared data
ARG - Defines build-time variables, usable during RUN

How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

Login to docker registry
docker login registry_server
Tag the image with full path to target repository in registry
docker tag imagename[:tag] registry_server/username/repository_name[:tag]
Push the image to registry
docker push registry_server/username/repository_name[:tag]

AshutoshBajpai

1. List of 5 Commands to Troubleshoot Docker Images

Question:
Please provide a list of five commands that are commonly used to troubleshoot issues related to Docker images. Briefly explain the purpose of each command.

Answer: Below are 5 troubleshooting commands:

logs Shows the container logs
ps Lists the containers
stats Displays container resources
top Displays container processes
events Shows real-time docker events

2. What is Docker Image?

Question:
What is a Docker image? Provide a concise definition and describe its primary components and purpose within the Docker ecosystem.

Answer: Docker images are the blueprint for containers, they typically contain the applications. Below are the primary components:

Layers - Represents each layer within the docker image.
Base Image - Represents the minimal OS image or application runtime environment
Dockerfile - scripting file used for creation of image for automation

3. How to Create a Docker Image Using a Container?

Question:
Describe the process of creating a Docker image using an existing container. Include the key commands involved in this workflow.

Answer: Export and import commands are used to create a docker image from an existing container.

docker export ash-ub-git-ap > ash-ub-git-ap.tar

Exports the filesystem of a container as a tar

cat ash-ub-git-ap.tar | docker import - ash-ub-git-ap:imported

Creates an image from a tarball

4. How to Create a Docker Image Using a Dockerfile?

Question:
Explain how to create a Docker image by utilizing a Dockerfile. Outline the general steps and the primary command used to build the image.

Answer:

Create the Dockerfile

# Dockerfile
FROM ubuntu:latest

RUN apt-get update && \
    apt-get install -y git apache2 && \
    apt-get clean

CMD ["/bin/bash"]

Save this as Dockerfile.

Build the image
docker build -t ubuntu-git-apache2:dockerfile .
List the images
docker images

5. Top 10 Instructions of Dockerfile

Question:
List the top ten instructions commonly used in a Dockerfile. For each instruction, provide a brief description of its function.

Answer:
FROM: Specifies the base image for building the new image
RUN: executes command
COPY: copies files from local to image
ADD: copies files, download from URLs and also can extract the archives
ENTRYPOINT: Defines the first command to execute once the container starts. Used before CMD
CMD: Defines the command to execute the once the container starts. Can be used to provide arguments to ENTRYPOINT
EXPOSE: used to expose the port
ENV: used to set variables
USER: used to run the apps in container as specific user
WORKDIR: Sets the working directory after executing a command

6. How to Upload Docker Images to a Docker Registry

Question:
Describe the procedure for uploading Docker images to a Docker registry. Include the sequence of commands typically required for this process.

Answer: The procedure to upload docker images to a Docker registry requires login to the docker registry and then push the image to the registry.

docker login docker tag ash-ub-git-ap:dockerfile ab/my_webapp:latest docker push ab/my_webapp:latest

RamEsh

List of 5 Commands to Troubleshoot Docker Images
1.find docker images
docker images
2.inspect images metadata
docker inspect image_name_or_id
3.check image history
docker history image_name_or_id
4.Check Container Logs To view logs from a running or stopped container:
docker logs container_id_or_name
What is Docker Image?
Docker image is an application , it dontians root fs + app fs + user fs
3.How to Create a Docker Image Using a Container?
1. run the base image to creat and start the container
  docker run -itd image_name
  2.exec container
  docker exec -it container_id_or_name /bin/bash
2. update the app and install required apps
  apt-get update
  apt-get install app_name
  4.exit
  5.using commit command create a image
  docker commit -m message container_id_or_name imagename:version
How to Create a Docker Image Using a Dockerfile?

1.make a dir for dockerfile
mkdir dock
1. create a dockerfile with base image detail and install app detail
  FROM baseimage:version
  RUN apt-get update && apt-get install git -y && apt-get instll apache2
  CMD ["/bin/bash"]
  3.build image using dockerfile
  docker build . -t imagename:version
  4.vaildate and run image file
  docker images
  docker run -itd iamgename
  6.How to Upload Docker Images to a Docker Registry
  1.login registry
  docker login
  2.authenticate
  3.push image into registry
  docker push iamgename