Merge pull request #691 from Namanv0509/intro-k8s

Adding intro to k8s workshop

Author: miacycle

content/en/learning-paths/mastering-kubernetes-for-engineers/introduction/concepts/_index.md

@@ -0,0 +1,111 @@
+---
+docType: "Course"
+title: "Concepts"
+description: "Kubernetes Basic Concepts"
+lectures: 1
+courseTitle: "Concepts"
+themeColor: "#00B39F"
+weight: 1
+order: 1
+cardImage: ""
+---
+
+{{< chapterstyle >}}
+
+
+## History
+
+Kubernetes also called *k8s* (a "k" followed by 8 chars and a "s") or simply *kube* means "Helmsman" in Greek. It is a container orchestrator inspired by Google Borg System which were orchestrating billions of containers on Google infrastructure.  
+
+Version *v1.0.0* of Kubernetes was released in July 2015, the last version as of today (October 2024) is *v1.31.1*. The release cycle is quite fast with 3 minor releases per year.
+
+## Main functionalities
+
+Kubernetes is a container orchestrator offering main functionalities, such as:
+
+- Management of applications running in containers
+- Self-healing
+- Service discovery
+- Usage of Secrets and Configurations
+- Long-running process and batch jobs
+- Role Based Access Control (RBAC)
+- Storage Orchestration
+
+## Manages applications in production
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/environments.png" align="center" width="100%" alt="environments" >}}
+
+## Major project in the open-source ecosystem
+
+Kubernetes is the first graduated project within the [CNCF](https://cncf.io/projects), it was followed by major players like [etcd](https://etcd.io) and [Prometheus](https://prometheus.io/) 
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/cncf.png" align="center" width="100%" alt="CNCF" >}}
+
+## What is a Kubernetes cluster made of ?
+
+A Kubernetes cluster is composed of nodes, where a node is either a virtual machine or a bare metal server. A node can belong to the Control Plane which run processes in charge of managing the cluster and the applications running on it. Or, a node can be a Worker dedicated to run Pods, a group of containers sharing a network stack and storage.
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/cluster.png" align="center" width="100%" alt="cluster" >}}
+
+## How to access a cluster
+
+A cluster usually comes with a kubeconfig file which contains all the information to communicate with the cluster API Server. This file can be used to configure the standard *kubectl* binary to manage the cluster. The kubeconfig file can also be used with tools like [k9s](https://k9scli.io/), [Mirantis Lens](https://k8slens.dev/), ... which give a higher level view of the cluster.
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/access.png" align="center" width="100%" alt="access" >}}
+
+## Various workload resources for different use cases
+
+To run a Pod we often rely on a higher level resource, instead of running it directly. The workload resources are:
+
+- Deployment : web server
+- DaemonSet : one agent per node
+- Job / CronJob : batch
+- StatefulSet : stateful application
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/workloads.png" align="center" width="100%" alt="workload resources" >}}
+
+A request that reaches a Service is load-balanced between the exposed Pods
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/service.png" align="center" width="100%" alt="service" >}}
+
+
+A Pod can use several resources
+
+- ConfigMap : contains configuration data
+- Secret : contains sensitive data
+- PersistentVolumeClaim / PersistentVolume : storage management
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/pod-resources.png" align="center" width="100%" alt="pod resources" >}}
+
+
+## Several types of resources
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/summary.png" align="center" width="100%" alt="Summary" >}}
+
+## An application runs in a Namespace
+
+
+{{< image src="/images/learning-path/intro-kubernetes/concepts/namespace.png" align="center" width="100%" alt="Namespace" >}}
+
+## Resource creation
+
+Each resource is defined in a YAML specification which is sent to the API Server using the kubectl binary.
+
+```yaml
+apiVersion: v1
+kind: Pod
+metadata:
+  name: www
+spec:
+  containers:
+  - name: www
+    image: nginx:1.24
+```
+
+```bash
+kubectl apply -f www.yaml
+```
+
+
+
+{{< /chapterstyle >}}