Docker uses a combination of namespaces and cgroups to provide isolation between containers, which allows multiple containers to run on the same host system without interfering with each other. Here’s a brief overview of how namespaces and cgroups work:
Namespaces: Namespaces provide a way to isolate different system resources between containers, such as the file system, network interfaces, process IDs, and more. Each container has its own set of namespaces, which are created when the container is started.
For example, each container has its own file system namespace, which means that the container sees a different file system than the host system. This allows containers to have their own root file system, which can be customized independently of the host system.
Cgroups: Cgroups provide a way to limit the resources that a container can use, such as CPU, memory, and disk I/O. Each container has its own set of cgroups, which are created when the container is started.
For example, you can use cgroups to limit the amount of CPU time that a container can use, or to limit the amount of memory that a container can allocate. This helps to prevent a single container from consuming all of the resources on a host system, which can cause other containers and applications to slow down or crash.
By using namespaces and cgroups, Docker is able to provide a lightweight form of isolation between containers, without the overhead of running a separate guest operating system for each container. This makes Docker much more efficient and scalable than traditional virtualization technologies.
Overall, namespaces and cgroups are critical components of Docker’s containerization technology, and play a key role in providing isolation and resource management for containers. By using namespaces and cgroups, Docker provides a secure and efficient platform for running containerized applications, and allows multiple containers to run on the same host system without interfering with each other.