How does docker see the driver

With the development of Internet technology, the rise of cloud computing and the application of containerization technology have gradually become the preferred technology for companies and developers. As one of the most popular containerization technologies currently, Docker is widely used in cloud computing, engine services and other fields, causing more and more developers to conduct in-depth research and exploration on it.

Docker is a tool for quickly creating, deploying and running applications using container technology. It can run multiple containers on a single machine. Each container can run a different application and can be isolated from other containers and the host operating system. Docker integrates the user space and kernel of the operating system, allowing applications to run directly inside the system without having to adopt an abstraction level similar to a virtual machine. In this way, Docker saves too much memory and CPU resources, greatly improves its operating efficiency, and the operating environment is constantly improving.

Docker has an important component - the driver, which provides different working modes and different installation methods for Docker. Drivers are the interface between Docker and low-level operating system resources (such as kernel, network/storage/system components). For the Linux operating system, the Docker driver is based on the network bridge. By using the packet filter inside the Linux operating system, it realizes the filtering, forwarding and NAT of network packets, thus realizing the network interoperability and hosting between Docker containers. Host to container network access.

Docker officially supports four different drivers: overlay2, aufs, devicemapper, and btrfs. Each driver has its advantages and disadvantages. Different drivers are suitable for different environments and application scenarios. We need to choose the most suitable driver according to our actual situation.

First, let’s take a look at the most commonly used overlay2 driver. overlay2 is a lightweight driver that is efficient and reliable, and implements hierarchical management of Docker images. In addition, overlay2 supports the most common features in Docker, such as a writable container layer and data sharing between containers, volumes, and host file systems. This allows an image to store only its changed parts, thereby increasing the deployment speed of Docker containers and reducing storage space usage.

Secondly, the aufs driver is an early Docker driver that can implement layered management of images and copy-on-write technology. It can mount different folders in the same virtual file system. This makes sharing files between different Docker containers very simple. Although it is slightly slower than overlay2, it is still a driver that can be useful in certain situations.

Third, the devicemapper driver is the implementation of delayed allocation of container file system space, copy-on-write mirroring and data snapshot functions. It enables allocation and expansion of container file system space using block-based storage drivers with LVM (Logical Volume Manager) volumes. This driver is an advanced block device mapping technology officially supported by Docker, which can support dynamic allocation of disk space to containers, so that operations within the container can be transparently reflected on the host.

Finally, the btrfs driver is a driver based on Copy-on-Write technology, which can provide more file system functions and management methods for Docker containers. This driver comes with some of the features of modern file systems, such as replication, snapshots on different storage devices, data compression and redundant backups. Overall, Btrfs is a well-rounded file system that provides many advanced options for Docker containers.

Today, when we pay attention to saving every byte, it is increasingly important to choose the docker driver that suits you. Choosing an inappropriate driver may cause some applications to malfunction, reduce system stability, and increase the difficulty of debugging. Therefore, choosing the right Docker driver makes container management more efficient and reliable.

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