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Kubernetes What are containers

Links: 110 Kubernetes Index

What are containers

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  • The container actually hosts cgroups, namespaces & union capable file system.
    • Because of these 3 a container looks and feels like an operating system.
The cgroups and namespaces capabilities of the Linux kernel.
  • cgroup: Control Groups provide a mechanism for aggregating/partitioning sets of tasks, and all their future children, into hierarchical groups with specialised behaviour.
  • namespace: wraps a global system resource in an abstraction that makes it appear to the processes within the namespace that they have their own isolated instance of the global resource.
cgroups = limits how much you can use; namespaces = limits what you can see (and therefore use)
  • cgroups provide resource metering and limiting like memory, CPU, block I/O, network, Device node (/dev/) access control
  • namespaces provides processes with their own view of the filesystem. We have multiple namespaces for pid, net, mnt, uts etc.


Last updated: 2022-09-05