Build_your_own_kubernetes_cluster_from_scratch_-_Part_1.pdf

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KUBERNETES, DEEP, DIVE Build your own kubernetes cluster from scratch - Part 1 Using Systemd to control Master/Worker components.

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Dridi Walid, [email protected] - Kubernetes Consultant / Trainer - Cloud Native Engineer @FnacDarty Linkedin: https://www.linkedin.com/in/dridi-walid Who am I ?

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1. Architecture Overview 2. Pause Container (POD) 3. ETCD 4. kube-apiserver 5. kubectl 6. kube-scheduler 7. kubelet 8. Run nginx pod 9. kube-proxy 10. kube-controller-manager 11. Q&A Agenda

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Architecture Overview

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1. Architecture Overview Node1 kube apiserver etcd controller manager scheduler kubectl kubelet Load Balancer End Users kubelet kube-proxy kube-proxy Node2 Container Runtime (Docker) Container Runtime (Docker) Pod1 Pod1 Developer Master Workers

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Pause Container

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2. Pause Container (POD) The ‘pause’ container is a container which runs a process that performs no function but sleeps forever and holds the network namespace for the pod. Pod should be the ﬁrst process with PID 1 otherwise it throws an error. Kubernetes creates pause containers to acquire the respective pod’s IP address and set up the network namespace for all other containers to join that pod. Docker image used for pause container is http://gcr.io/google_containers/pause-amd64:3.0

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2. Pause Container (POD) Pause Nginx Redis Linux Network Namespace 10.10.0.2 localhost:80 localhost:6379 /cache cache-volume POD

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2. Pause Container (POD) Pause Nginx Ghost localhost IPC Network PID UTS(Hostname) ● IPC: Interprocess Communication ● Network: Virtual Network Interface ● PID: Process IDs ● UTS: Hostname Source: http://man7.org/linux/man-pages/man7/namespa ces.7.html Shared Linux Namespaces:

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2. Pause Container (POD) IPC Pause docker images: Image: gcr.io/google_containers/pause-amd64:3.0 Source Code: https://github.com/kubernetes/kubernetes/tree/master/build/pause

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2. Pause Container (POD) How to create a pod by using the pause container and sharing namespaces: Add nginx container to this pod to work as proxy to ghost container on port 2368: Start the pause container with Docker: // nginx.conf error_log stderr; events { worker_connections 1024; } http { access_log /dev/stdout combined; server { listen 80 default_server; server_name _; location / { proxy_pass http://127.0.0.1:2368; } } }

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2. Pause Container (POD) How to create a pod by using the pause container and sharing namespaces: Add ghost container to this pod: Browse to localhost:8090, you should have ghost frontpage

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2. Pause Container (POD) Inspect container IPs

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2. Pause Container (POD) Resources: ● https://www.ianlewis.org/en/almighty-pause-container ● https://en.wikipedia.org/wiki/Linux_namespaces ● http://man7.org/linux/man-pages/man7/namespaces.7.html

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ETCD

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● Highly-available key value store thanks to Raft Distributed Consensus Protocol, ● Written in Go, ● Good for: ○ Shared conﬁguration, ○ Service Discovery ● Simple http interface (Stored Objects are requested using curl) ● Watch speciﬁc keys for changes and react to changes in values, ● ... Features: 3. ETCD

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Installation: 3. ETCD

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3. ETCD Systemd unit:

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Swagger documentation: 3. ETCD

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3. ETCD

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kube-apiserver

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4. kube-apiserver API Server — The Gateway to Kubernetes ● Kubernetes objects are exposed via simple REST API through which basic CRUD operations are performed and API Server acts as the gateway to the platform. ● Internal components such as kubelet, scheduler, and controller access the API via the API Server for orchestration and coordination. ● The distributed key/value database, etcd, is accessible only through the API Server

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4. kube-apiserver Installation:

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Systemd unit: 4. kube-apiserver

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Kubectl

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5. Kubectl What’s kubectl: Is a client for the Kubernetes API, which is an HTTP API and every Kubernetes operation is exposed as an API endpoint and can be executed by an HTTP request to this endpoint.

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5. Kubectl Installation:

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5. Kubectl Developer k8S Cluster API SERVER ... localhost:800 Kubectl ﬂow

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5. Kubectl Kubectl version

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5. Kubectl UI User Interface API CLI Command Line Interface Kubernetes Master Node 1 Node 1 Node 1 Node 1 Image Registry

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5. Kubectl Get k8s version using a native curl http request

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5. Kubectl The conﬁguration ﬁle is by default located in: Set the KUBECONFIG environment variable: