for kubernetes objects in detail read

• https://trainingportal.linuxfoundation.org/learn/course/introduction-to-kubernetes
• https://kubernetes.io/docs/concepts/

objects

namespaces isolate/partition kubernetes entities into parts
which are from a kubernetes view to be managed seperately
which does not mean pods in different namespaces can't communicate but
e.g. that they are not using the same config maps, secrets though
kubectl get namespace lists all namespaces
kubectl create namespace konoha_ns creates a namespace

configmaps of a namespace can point to an address in another
namespace thus contacting services in other namespaces.
Access and resource limitation works via namespaces.

volumes and nodes are not namespaced.

for something that comes close to the hints of a language server
https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.30/#container-v1-core

                 pod                   service                     secret
                  ▲
                  │
                  │has one or more                                 configmap
                  │
              replicaset
                  ▲                                                volume
                  │
                  │has
                  │
               deployment                             daemonset

components

# text listed in a box is a listing of so called "node agents"
     ┌─────────────┐
     │control plane│
     ├─────────────┴────────────────────────────┐
     │    ┌────┐                                │
     │    │node│                                │
     │    ├────┴───────────────────────────┐    │
     │    │   api-server ◄─────────────────┼────┼───────┐
     │    │   controller-manager           │    │       │
     │    │   scheduler                    │    │       │
     │    │   etcd                         │    │       │
     │    │   kubelet                      │    │       │
     │    │   kubeproxy                    │    │       │
     │    │   container runtime            │    │       │
     │    │   addons                       │    │       │
     │    └────────────────────────────────┘    │       │
     └──────────────────────────────────────────┘       │
                                                        │
                           ┌────┐                       │
                           │node│                       │
                           ├────┴────────────────────┐  │
                           │   kubelet───────────────┼──┤
                           │   kubeproxy─────────────┼──┘
                           │   container runtime     │
                           │   addons                │
                           └─────────────────────────┘

---

for a test environment on one machine I use minikube

getting kubernetes on my servers I would use kubeadm

---

command cache:

kubectl apply
-f ./service.yaml
-f ./secret.yaml
-f ./deployment.yaml
-f ./configmap.yaml
-f ./mongo-express/service.yaml
-f ./mongo-express/deployment.yaml

clear; kubectl get all

kubectl delete deployment mongodb-d mongodb-express-d;
kubectl delete configmap mongodb-c;
kubectl delete service mongodb-s mongodb-express-s;
kubectl delete secret mongodb-sec;

---

to run kubernetes in a docker container docker run --privileged --name k3s -d -e K3S_TOKEN=mynodetoken rancher/k3s:v1.27.9-k3s1 server

---

create a cluster

read https://kubernetes.io/docs/setup/production-environment/tools/