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Showing posts with the label Containers

Kubernetes - Concepts, Components & Use-Cases

Kubernetes (K8s) is an open-source container-orchestration platform for automating application deployment, management and scaling. Concepts 1. Kubernetes uses the concepts of pods - an object that consists of one or more containers which share network namespace 2. Kubernetes automates deploying, scaling and managing containerized application on a group (cluster) of (bare metal or virtual) servers, such as ensuring that in case a container within a pod crashes, it will be restarted. Use case: A developer needs 5 application containers on a host. The way he can do it using docker is type the command: "docker run <application_name>" individually 5 times, to create 5 containers on the host machine. What if a production environment requires 200 containers? If you have an automation script that does run the above command 200 times to create 200 containers, how do you monitor them? How do you ensure the underlying host resources aren't stretched or depleted? K8s to the res

Container Concepts

Container = Namespaces + CGroups + Layered Filesystem Namespaces A 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. Changes to the global resource are visible to other processes that are members of the namespace but are invisible to other processes. Namespaces limit how much you can see and therefore use: 1. PID 2. Network 3. UTS 4. Mount 5. IPC 6. User CGroups (Control Groups) Control groups are a Linux kernel feature which allows processes to be organized into hierarchical groups whose usage of various types of resources can then be limited and monitored. CGroups limit how much you can use: 1. CPU 2. Memory Layered Filesystem Different files and directory structures are layered in order and on top of each other to be reflected as one directory tree.      Layered Filesystem allows reuse and push/pull deltas. It's an advanced multilayered unificati