Is it too troublesome to install dependencies directly on the server? Why do we have to reconfigure every time we go online if the environment is down? In fact, many teams have encountered these problems. Especially when deploying applications in a Linux environment, the trouble is not the code, but various environmental dependencies, version conflicts, and inconsistent configurations. Today, let's talk about what is so good about using Docker images to deploy Linux applications?

　　A Docker image is like a "lightweight Linux file system + runtime packaging", which encapsulates an application and everything it needs (running environment, libraries, configuration). The image is immutable and read-only. By running the image, you can quickly generate a container (a writable and interactive instance).

　　Seven advantages of using Docker images to deploy Linux applications:

　　Environmental consistency: Development environment = production environment, which is one of Docker's biggest killers.

　　Before: Local debugging is OK, but there is an error when going online. Operation and maintenance can't find the problem, and the development blames: "It can run here!"

　　Now: Use the same image to run locally, test, and online, with completely consistent configuration. What you see is what you get, greatly reducing "bugs caused by different environments"

　　In a word: images are deterministic, while naked deployment is metaphysics.

　　Fast deployment and rollback: go online in seconds.

　　Deployment in traditional ways can take several minutes or even dozens of minutes. But with Docker images, you only need to start the container and it will be done in a few seconds.

　　Want to roll back? Docker run old-image, the recovery is so fast. Especially suitable for teams with frequent iterations and continuous delivery. CI/CD perfectly combines Docker image building and deployment, and automates the entire process.

　　Strong isolation: does not affect the host machine,

　　Docker containers run in independent user spaces and are isolated from the host system. You can run multiple different versions of Python, MySQL, Node.js, and Java on the same server. They do not interfere with each other and do not pollute the system. No more worrying about "which version of the library to uninstall or not".

　　Flexible migration: images can run anywhere

　　Docker images are platform-independent. After you build the image, you can copy it to another Linux host and run it directly, upload it to a private warehouse for deployment, and flexibly schedule it in the container service.

　　Migration is no longer a matter of copying configuration + packaging code + verifying dependencies.

　　Easy version control and traceability

　　Each image has a unique tag or hash. You can: add a version number to each build, accurately control the online version, and quickly locate the problem image.

　　Similar to Git, Docker images can be rolled back, compared, and managed.

　　Save resources and expand capacity quickly

　　Docker containers share the host kernel and are very lightweight to start. Unlike virtual machines, they do not "run from BIOS to system once". During business peak hours, you can pull up multiple copies in seconds:

　docker run -d --name app1 yourapp
　docker run -d --name app2 yourapp

　　Use Nginx and Traefik for load balancing to easily cope with sudden traffic growth.

　　More secure and controllable

　　Although Docker does not mean absolute security, the container running permissions can be configured to prevent the code from arbitrarily accessing host resources. The image can be streamlined when building, removing redundant tools and reducing the attack surface. It supports read-only containers, firewall policies, network isolation, etc. Coupled with enterprise-level tools, it can achieve full process control of image content, source, and permissions.

　　Using Docker images to deploy Linux applications is not a trend, but a trend. It makes the environment no longer a problem, deployment no longer risky, and expansion no longer costly. It is the first step in your operation and maintenance automation and a pass for team collaboration.