https://github.com/rishant/kubernetes-learning
Kubernetes-learning
https://github.com/rishant/kubernetes-learning
Last synced: 10 months ago
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Kubernetes-learning
- Host: GitHub
- URL: https://github.com/rishant/kubernetes-learning
- Owner: rishant
- Created: 2024-07-11T04:38:30.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2024-12-07T07:20:08.000Z (about 1 year ago)
- Last Synced: 2024-12-07T08:19:32.377Z (about 1 year ago)
- Size: 2.93 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
"# Kubernetes-learning"
### References:
```
https://kubernetes.io/docs/reference/kubectl/quick-reference/
https://spacelift.io/blog/kubernetes-cheat-sheet
https://www.youtube.com/watch?v=_f9ql2Y5Xcc&list=PLl4APkPHzsUUOkOv3i62UidrLmSB8DcGC&index=8
https://github.com/piyushsachdeva/CKA-2024/tree/main
https://www.youtube.com/watch?v=yVLXIydlU_0&list=PLl4APkPHzsUUOkOv3i62UidrLmSB8DcGC&index=11
```
## Kubernetes RoadMap
```
Kubernetes
├── Cluster
│ ├── Node
│ │ ├── Master Node
│ │ │ ├── API Server
│ │ │ ├── Controller Manager
│ │ │ ├── Scheduler
│ │ │ └── etcd
│ │ ├── Worker Node
│ │ ├── Kubelet
│ │ ├── Kube-Proxy
│ │ └── Container Runtime
│ └── Namespace [Isolation - namespace is a way to divide cluster resources between multiple users or applications]
├── Workloads
│ ├── Pod [Deploy Image]
│ ├── ReplicationController [Auto Scale (Container Replicas), Auto-Healing (Fault-tolarance spawn), Not-applied-with-existing-pods]
│ ├── ReplicaSet [Auto Scale (Container Replicas), Auto-Healing (Fault-tolarance spawn), Applied-with-existing-pods]
│ ├── Deployment [Stateless Microservices application] (Rolling Updates | Rollbacks | Blue GreenCanary )
│ ├── StatefulSet [Statelful Database application]
│ ├── DaemonSet [Logging, Monitoring]
│ ├── Job
│ └── CronJob
├── Services & Networking
│ ├── Service
│ │ ├── ClusterIP [Inter communication - Expose Cluster IP --> to talk Inter Container communication --> example: Front App Container talk to Backend Application Container]
│ │ ├── NodePort [External Communication - Expose Node Port --> to access publicly deployed --> Frontend Web Application --> via Browser]
│ │ ├── LoadBalancer
│ │ └── ExternalName
│ ├── Ingress
│ ├── NetworkPolicy
│ └── DNS
├── Storage
│ ├── Volume
│ │ ├── emptyDir
│ │ ├── hostPath
│ │ ├── nfs
│ │ ├── awsElasticBlockStore
│ │ ├── gcePersistentDisk
│ │ ├── azureDisk
│ │ ├── azureFile
│ │ ├── cephFS
│ │ ├── iscsi
│ │ ├── local
│ │ └── csi
│ ├── PersistentVolume
│ ├── PersistentVolumeClaim
│ └── StorageClass
├── Configuration
│ ├── ConfigMap
│ ├── Secret
│ ├── ResourceQuota
│ ├── LimitRange
│ ├── HorizontalPodAutoscaler
│ └── PodDisruptionBudget
├── Security
│ ├── ServiceAccount
│ ├── Role
│ ├── RoleBinding
│ ├── ClusterRole
│ ├── ClusterRoleBinding
│ └── PodSecurityPolicy
└── Extensions & Add-ons
├── Helm
├── Operators
├── CustomResourceDefinition (CRD)
├── Prometheus
├── Grafana
├── Fluentd
├── Istio
├── Linkerd
└── Metrics Server
```
## `Configmap`
Summary of ConfigMap Usage in Kubernetes:
| Method | Use Case |
| ------------ | ----------|
| Environment Variables | Store app configurations and inject them into the container. |
| Mounted as Files in a Volume | Share configuration files with the container. |
| Command-Line Arguments | Pass ConfigMap values as container arguments. |
| Entire Volume | Mount all ConfigMap keys as individual files. |
| Other Kubernetes Resources | Use in Deployments, StatefulSets, etc., for scaling purposes. |
## 1. ConfigMap - Environment Variables:
```
---configmap_env_variables.yaml---
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
APP_NAME: "MyApp"
APP_VERSION: "1.0"
----------------------------------
cmd:/> kubectl apply -f configmap_env_variables.yaml
--------deployment.yml----------
apiVersion: v1
kind: Pod
metadata:
name: app-pod
spec:
containers:
- name: app-container
image: nginx
env:
- name: APP_NAME
valueFrom:
configMapKeyRef:
name: app-config
key: APP_NAME
- name: APP_VERSION
valueFrom:
configMapKeyRef:
name: app-config
key: APP_VERSION
----------------------------------------
```
## 2. Mounted as Files in a Volume
```
-----configmap_mount_as_file.yaml-----
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
config.json: |
{
"app_name": "MyApp",
"app_version": "1.0"
}
--------------------------------------
cmd:/> kubectl apply -f configmap_mount_as_file.yaml
-------deploymnet.yaml-------
apiVersion: v1
kind: Pod
metadata:
name: app-pod
spec:
containers:
- name: app-container
image: nginx
volumeMounts:
- name: config-volume
mountPath: /etc/config
volumes:
- name: config-volume
configMap:
name: app-config
---------------------------------------
Note:
1. This will mount the config.json file into the container at /etc/config/config.json.
```
## 3. Command-Line Arguments
```
-------ConfigMap_cmdline.yaml--------
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
greeting: "Hello, World!"
--------------------------------------
cmd:/> kubectl apply -f ConfigMap_cmdline.yaml
-------deploymnet.yaml-------
apiVersion: v1
kind: Pod
metadata:
name: app-pod
spec:
containers:
- name: app-container
image: busybox
command: ["echo"]
args:
- "$(GREETING)"
env:
- name: GREETING
valueFrom:
configMapKeyRef:
name: app-config
key: greeting
-------------------------------
```
## 4. ConfigMap as an Entire Volume
```
-------ConfigMap_entire_volume.yaml--------
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
app.properties: |
app.name=MyApp
app.version=1.0
db.properties: |
db.name=MyDB
db.version=2.0
--------------------------------------
cmd:/> kubectl apply -f ConfigMap_entire_volume.yaml
-------deployment.yaml-----------------
apiVersion: v1
kind: Pod
metadata:
name: app-pod
spec:
containers:
- name: app-container
image: nginx
volumeMounts:
- name: config-volume
mountPath: /etc/config
volumes:
- name: config-volume
configMap:
name: app-config
---------------------------------------
Notes:
This will create two files inside the container:
/etc/config/app.properties
/etc/config/db.properties
```
## 5. Used by Another Kubernetes Resource
```
-------ConfigMap_another_k8s_resource.yaml--------
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
APP_NAME: "MyApp"
---------------------------------------------------
cmd:/> kubectl apply -f ConfigMap_another_k8s_resource.yaml
-------deployment.yaml-----------------
apiVersion: apps/v1
kind: Deployment
metadata:
name: app-deployment
spec:
replicas: 2
selector:
matchLabels:
app: my-app
template:
metadata:
labels:
app: my-app
spec:
containers:
- name: app-container
image: nginx
env:
- name: APP_NAME
valueFrom:
configMapKeyRef:
name: app-config
key: APP_NAME
-----------------------------------------
```