Docker sits “on top” of the host operating system. Each application is then bundled in an image that contains all the configuration, libraries, files and executables the application needs to run.
What is docker host OS?
Docker is a container-based technology that only virtualizes the operating system. The Docker container sits on top of its physical server and the host operating system (most often Linux or Windows.)
Does Docker need OS?
Containers run directly on the kernel of hosting OS, this is why they are so lightweight and fast (plus they provide isolation of processes and nice distribution mechanism in the shape of docker hub, which plays well with the ability to connect containers with each other).
Can Docker containers have different OS?
Short answer is yes. Each docker container uses its own file system (has its own mount name space). As long as you don’t use any kernel specific features (like insmod of a kernel module in an application running inside a privileged container on Linux), containers themselves are portable.
What is Docker guest OS?
Guest OS can be any OS, like Linux or Windows, irrespective of host OS. In contrast, Docker containers host on a single physical server with a host OS, which shares among them. Sharing the host OS between containers makes them light and increases the boot time.
Does Docker use host kernel?
No. Docker image/container only has the application layer of the OS and uses the kernel and CPU of the host machine. … So if you have multiple docker containers running on a host they will all share the kernel of the host.
Does every Docker image contain OS?
Every image contains an complete os. Special docker made OS’s come with a few mega bytes: for example linux Alpine which is an OS with 8 megabytes! But bigger OS like ubuntu/windows can be a few gigabytes.
What OS do containers use?
Yes, they do. Every container is based on an OS image, e.g. Alpine, CentOS or Ubuntu. They just share the host kernel, but run every user-space process in a separate name space specific for that container.
Do containers have operating systems?
Unlike VMs, containers do not have an OS within it. They simply share the underlying kernel with the other containers.
Are Docker containers OS independent?
According to Docker, a container is ” a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run it.” And since containers are platform-independent, Docker can run across both Windows- and Linux-based platforms.
Can I run an OS in a container?
Containers are a type of software that can virtually package and isolate applications for deployment. Containers can share access to an operating system (OS) kernel without the traditional need for virtual machines (VMs).
Is a Docker base image the OS?
AFAIK, the docker image bases use standard OS images. In your example, it’s not like there’s a custom CentOS build which knows to use the parent’s kernel?
Does Docker image depend on OS?
Yes, docker images are OS-dependent as not all the images run on every OS. The reason is that every docker container that originated from some image will use the kernel of the host machine and not its own, unlike virtual machines.
What is a host or container host?
Container Host: Also called the Host OS. The Host OS is the operating system on which the Docker client and Docker daemon run. In the case of Linux and non-Hyper-V containers, the Host OS shares its kernel with running Docker containers. For Hyper-V each container has its own Hyper-V kernel.