DigitalOcean Kubernetes production Cluster

Description of our DOKS setup and tools/applications w/ configurations and brief tutorials.

-> All the stuff comes without warranty! Think twice about any configuration or approach here!

Setup Overview

We use DigitalOcean Managed Kubernetes (in Amsterdam Datacenter 3/AMS3).
The setup is following:

• Kubernetes Cluster w/ 2 Node workers s-1vcpu-2gb-intel,
• DigitalOcean Load Balancer for accepting traffic - incoming HTTP requests,
• Ingress Controller w/ nginx for routing traffic within Cluster into Kubernetes Services.

We use Kubernetes Dashboard, Lens (via kubectl) and kubectl for monitoring and adminsitration. Majority of application administration is performed by applying config files in following manner kubectl apply -f kubernetes-ingress-config.yaml. Overview is carried on either in GUI or by querying via kubectl, such as kubectl get nodes, kubectl get deployments or kubectl describe ingress hello-kubernetes-ingress.

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Our K8s cluster overview

1. Cluster Visualization - blue components are either external (DNS Services, Load Balancer / DBs or Image Registry) or added to the cluster later (Ingress). It shows architecture of MySQL & Redis databases in cluster and one PHP app utilizing it. Orange color is used for external communication/traffic.
2. Running cluster architecture - 1 DOKS (Master) & 2 Nodes (2nd+ nodes are optional - therefore blue).
3. DOKS Volume policy - 1 Volume can be attached to just 1 Node at the time. We show how to run 1/1 Replica databases, which is sufficient for simple usecase like ours. You can use Managed by cloud provider ones.
4. YAML config file - basic example schema.

Tools running in K8s cluster

• Ingress - (1-Click apps/Helm) kubernetes-ingress-config.yaml,
• cert-manager - (1-Click apps/Helm) !TODO configs,
• mysql-deployment/ - MySQL Database Server in K8s Cluster.
  • 0-encode-base64.sh - Prepare base64 encoded root passwd.
  • 0-mysql-secret.yaml - Apply MySQL Secret onto cluster.
  • 1-pv-pvc-mysql.yaml - Create PV and get PVC (Persistent Volume and subsequent Persistent Volume Claim on it).
  • 2-deployment-mysql.yaml - Deployment of MySQL utilising PVC as volume and mounted /var/lib/mysql on it.
  • 3-service-mysql.yaml - Expose as mysql-service port 3306.
• Adminer - (adminer Docker image Deployment) Adminer GUI client for browsing DBs running on mysql-service (expose from mysql-deployment pt.3) run at adminer.yourdomain.com,
• redis-deployment/ Remote Dictionary Server in K8s Cluster.
  • 0-encode-base64.zsh - Prepare base64 encoded root passwd.
  • 0-redis-secret.yaml - Apply Redis Secret onto cluster.
  • 1-pv-pvc-redis.yaml - Create PV and get PVC (Persistent Volume and subsequent Persistent Volume Claim on it).
  • 2-deployment-redis.yaml - Deployment of Redis utilising PVC as volume and mounted /var/lib/mysql on it.
  • 3-service-redis.yaml - Expose as redis-service port 6379.
• Prometheus monitoring - IN THE PROCESS. 1-Click app DOKS Helm package bugged.

Detailed installation of Databases - steps in READMEs:

• mysql-deployment/README.md,
• redis-deployment/README.md.

App Configs - run in K8s cluster

• adminer.yaml - Adminer tool from up. // <- use this
• app-hello-kubernetes-first.yaml - Dummy application 1. // <- use this
• app-hello-kubernetes-second.yaml - Dummy application 2. // <- use this
• app-swimmpair.yaml - Production SwimmPair - example of LAMP web application w/ all necessary services. // <- don't use this

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Kubernetes Objects - general basic must-know

Cluster Architecture

• Nodes - Master Node, Worker Nodes, (The Kubernetes API)

Workload

• Deployments - define Pods and ReplicaSets

Services, Load Balancing, and Networking

• Ingress
• Service (port, targetPort)

Storage

• Volume - Persistent Volume
• Persistent Volume Claim

Configuration

• Secret

Tasks

• HorizontalPodAutoscaler - attached to Deployment