Why Docker Containers Revolutionize Application Deployment

Container technology originates from Linux kernel virtualization, providing lightweight isolation. Docker popularized containers by enabling portable packaging of applications, libraries, and even the OS filesystem.

Compared to virtual machines, containers offer higher resource efficiency, faster startup (seconds or milliseconds), consistent runtime environments, easier migration across platforms, and simpler maintenance and scaling.

Key Docker Concepts

Image : packaged application with its dependencies and filesystem.

Image Registry : stores and shares images, can be public or private.

Container : runtime instance of an image, isolated process on the host.

Typical Docker Workflow

1. Build an image on the development machine.

2. Push the image to a registry.

3. Pull the image on a production host and run a container.

Installation Example (Linux)

curl -fsSL get.docker.com -o get-docker.sh
sh get-docker.sh

For CentOS 8, use a lower‑version package:

wget -O /etc/yum.repos.d/docker-ce.repo https://repo.huaweicloud.com/docker-ce/linux/centos/docker-ce.repo
sed -i 's+download.docker.com+repo.huaweicloud.com/docker-ce+' /etc/yum.repos.d/docker-ce.repo
yum install docker-ce-18.06.3.ce -y
systemctl restart docker

Building and Running a Simple Image

# Dockerfile
# Use official Nginx image
FROM nginx:alpine
# Modify index.html
RUN echo "hello world" > /usr/share/nginx/html/index.html
EXPOSE 80

Build and tag the image: docker build -t hello . List images:

# docker images
REPOSITORY   TAG    IMAGE ID   CREATED          SIZE
hello       latest d120ec16dcea 17 minutes ago 158MB
nginx       alpine eeb27ee6b893 2 months ago   148MB

Run the container locally: docker run -p 8080:80 hello Access http://127.0.0.1:8080 to see “hello world”.

Pushing to Huawei Cloud SWR

Tag the image with the registry address and push:

# docker tag hello swr.cn-east-3.myhuaweicloud.com/container/hello:v1
docker push swr.cn-east-3.myhuaweicloud.com/container/hello:v1

Pull the image later with:

docker pull swr.cn-east-3.myhuaweicloud.com/container/hello:v1