Dyson Liu's Coding Journey: Create Your Docker Image

Friday, January 27, 2023

Create Your Docker Image

Create Your Docker Image

The article is described in the following scenarios:

Get the Nginx Image from Docker Registry (Container Registry)
Execute the Container and add/change files
Return to the background process and check the status
Build the new Image, and
Finally, upload to the Docker Registry

Use Nginx as a Web Server

Get nginx image from Docker Hub
```
docker pull nginx
```

Run nginx as a container with the name webserver

docker run -d -p 8080:80 --name webserver nginx

Options	Description
-d	--detch, Run container in background
-p	Publish all exposed ports to the port, format host-port:container-port
--name	Assign a name to the container
nginx	Docker image or ID

After execution, enter localhost:8080 in your host browser and see the “Welcome to nginx!” web page.

Stop, start and restart the container

docker stop webserver
docker start webserver
docker restart webserver

Make sure that the container is in the execution, then type the following command to enter the shell environment
```
docker exec -it webserver sh
```
Options Description

-i --interactive, Keep STDIN open even if not attached

-t --tty, Allocate a pseudo-TTY

The default home page of Nginx is located at /usr/share/nginx/html/index.html; you can use the following command to confirm it.

# cat /usr/share/nginx/html/index.html

Enter exit to leave the terminal and return to PowerShell.
Copy the file to replace the default web page with a simple Hello World.
```
<!DOCTYPE  html>
<html>
<head>
	<title>Hello World Sample</title>
</head>
<body>
	Hello World!
</body>
</html>
```
Overwrite the container’s homepage with the cp command.
```
docker cp ./index.html \
  webserver:/usr/share/nginx/html
```
Enter localhost:8080 in the browser, and you can see that the homepage has been updated.

Create a new image
Use docker commit to save the container as a new image.

docker commit webserver \
  <docker_hub_account> \
  /hello_world_nginx:1.0

Stop the container and remove it.

docker stop webserver
docker rm webserver

Run the newly docker image, and test in the browser.

docker run -d -p 8080:80 \
  --name webserver \
  <docker_hub_account>\
  /hello_world_nginx:1.0

Login to docker hub and upload the new docker image.
```
docker login
```
```
docker push \
  <docker_hub_account>\
  /hello_world_nginx:1.0
```
After completion, you can see the new docker image on the docker hub web page.

Reference:
How to Create a Docker Image From a Container

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