How can Docker settings be defined to coexist with existing applications?

Using namespaces and cgroups is the correct approach for defining Docker settings to coexist with existing applications because these technologies provide the isolation and resource management that Docker needs to operate effectively alongside other applications on the same host.

Namespaces allow Docker to create isolated environments for each container, ensuring that the processes running inside a container are separate from those running in the host OS and in other containers. This isolation prevents conflicts between applications and also enhances security, as containers can't interfere with each other.

Cgroups (control groups) are used to limit and prioritize the resources (like CPU and memory) that each container can use. This ensures that a container does not consume all the resources of the host machine, which could impact the performance of existing applications running on that host. Together, namespaces and cgroups help maintain a stable environment, ensuring that Docker containers can coexist with existing applications without affecting their performance or stability.

Utilizing containers exclusively may not be viable due to existing applications that cannot be containerized. Modifying application source code is often impractical or unnecessary, as many applications are designed to run in their own runtime environments without adjustments. Creating virtual machines, while providing a level of isolation, introduces additional complexity and overhead not typically needed for basic coexistence scenarios, making it less efficient