Basic Questions/Answers for Docker.

Question 1: What is Docker?

Answer: Docker is an open-source containerization platform. It used to automate deployment of any application, using lightweight portal container. 

Question 2: What is Container?

Answer:  Container is deployed bundle of an application that contain all necessary dependencies and configuration files.

All the elements shared with based OS kernel.  

Question 3: What is dangling docker image?

Answer: Dangling images are untagged Docker images that are not associated with any container. They are created when they are overwritten with a new image with the same name and tag.

Question 4: What is Container lifecycle?

Answer: Container Following is the most common.

• Create container.
• Run container.
• Pause Container.
• Stop Container.
• Start Container.
• Restart Container.
• Kill Container.
• Destroy container.

Question 5: Mostly used Docker Commands.

Answer: Following are the commonly used command.

1. To run a container.
   

   docker run -it -d -p <hostport:container-port>        <image-name> 
   
   Example: docker run -it -d -p 8080:80 nginx

2. To list all running containers.
   

   docker ps

3. To list all container including exit one.
   

   docker ps -a

4. To stop container.
   

   docker stop <container-name or container-id> 
   
   example: docker stop nginx

5.  To remove container.
   

   docker rm <container-name>
   
   example: docker rm nginx

6. To build a Docker image.
   

   docker build -t <image-name:tag> 
   
   example: docker build -t nginx:v1
   

7. To list Docker images
   

   docker image ls or docker images

8. To remove Docker images
   

   docker rmi <image-name/or image-id>
   
   docker rmi nginx:v1

9. To remove unused docker images
   

   docker image prune -a