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https://github.com/amazingandyyy/k8-cert
Notes for Kubernetes Certified Application Developer (CKAD)
https://github.com/amazingandyyy/k8-cert
ckad ckad-certification k8s kubernetes
Last synced: about 1 month ago
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Notes for Kubernetes Certified Application Developer (CKAD)
- Host: GitHub
- URL: https://github.com/amazingandyyy/k8-cert
- Owner: amazingandyyy
- Created: 2020-01-10T19:24:30.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2020-01-17T06:35:38.000Z (about 5 years ago)
- Last Synced: 2024-10-28T04:04:09.937Z (3 months ago)
- Topics: ckad, ckad-certification, k8s, kubernetes
- Language: JavaScript
- Homepage:
- Size: 571 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# K8S
```
kubectl config set-context --current --namespace=
```
## Certification
### core
- pod
- deployment
- replicaSets
- namespaces
### configurations
#### ConfigMaps
- imperative
- use `kubectkl create configMap --from-literal==`
- use `kubectkl create configMap --from-from=`
- declarative
- kind: ConfigMaps(v1)
- no spec, data install, then key: value pairs
- use configmap in pods
```yaml
spec:
containers:
- name: pod-name
image: docker/pod
ports:
- containerPort: 8080
envFrom:
- configMapRef:
name: app-config
# key: APP_COLOR (single env)
```
#### Secret
- imperative: similar to configMap
- declarative
```yaml
spec:
envFrom:
- secretRef:
name: app-config
```
or inject from volume
```yaml
spec:
volumes:
- name: app-secret-volume
secret:
secretName: app-secret
```
#### SecurityContext
- declarative on container or pod level
```yaml
spec:
securityContext:
runAsUser: 1000
capabilities:
add: ["MAC_ADMIN"]
```
#### Resource
```yaml
spec:
containers:
- name: image-name
resources:
request:
memory: "1Gi"
cpu: 1
limits:
memory: "2Gi"
cpu: 2
```
### Taint & Tolerations
- `kubectl tain nodes node-1 app=blue:NoSchedule`
- pod.yaml
```yaml
...
spec:
containers:
- name: nginx
image: nginx
tolerations:
- key: "app"
operator: "Equal"
value: "blue"
effect: "NoSchedule"
```
## Node Affinity
```yaml
spec:
containers:
...
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: app_type
operator: In
values:
- beta
```
### Service account
- `kubectl create sa dashboard-sa` it will then create a secret token e.g. dashboard-sa-token-kbbdn
- `kubectl describe secret dashboard-sa-token-kbbdn`
- add to pod with spec.serviceAccount
## Topics
### Multi-container Pod
```yaml
spec:
containers:
- name: simple-webapp
image: docker/simple-webapp
ports:
- containerPort: 8080
- name: log-agent
image: docker/log-agent
- name: ...
```
- logs design patterns:
- sidecar(small container along with the main app)
- adapter(every main app send to one small container before save to DB)
- ambassador(send to a centralized small container and then save to DB)
### Observability
- spec.readinessProbe: health check to make sure the app is really running after deploying
```yaml
spec:
readinessProbe:
httpGet:
path: /ready
port: 8080
initialDelaySeconds: 10
periodSeconds: 5
failureThreshold: 8
```
- spec.livenessProbe
- health check to avoid when the pod is running but service is down
### Labels
- labels
- use metadata.labels
- or use `kubectl label pods pod-name key=value`
- or use `kubectl run my-server --image=nginx --labels="key=value,env=prod"`
- select `kubectl get pods --selector env=pod`
- spec.selector
- spec.selector.matchLabels.key: value
- example: rs uses selector to find the pod, then service uses the label to connect to the pod in the rs
- 
- metadata.annotations
### Update & Deployment
- spec.strategy.type can be “Recreate” or “RollingUpdate”(the default value)
- rolling update
- `kubectl apply -f ` will trigger a rolling updates
- rollout
- use `kubectl rollout status deployment/myapp-deployment`
- use `kubectl rollout history deployment/myapp-deployment`
### Job/CronJob
- kind: Job(batch/v1beta1), need a pod in spec.template
- spec.schedule: "*/1 * * * *"
- kind: CronJob(batch/v1), need a pod in spec.template
### Services** use selector to apply to p
- kind: Service(v1)
- spec.type: NodePort
- 
- spec.ports
- targetPort
- port
- nodePort (to the outside world)
- spec.selector
- spec.type: ClusterIP
- spec.ports
- targetPort
- port (act like a load balancer)
- spec.selector
### Ingress
- Ingress Controller = Deployment + Service + ConfigMap + Auth
- 
- kind: Ingress - Ingress resources
- one service
```yaml
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: test-ingress
spec:
backend:
serviceName: testsvc
servicePort: 80
```
- route to multiple services
```yaml
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: simple-fanout-example
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
# (O) http://:/watch --> http://:/
# (X) http://:/watch --> http://:/watch
spec:
rules:
- host: foo.bar.com
http:
paths:
- path: /foo
backend:
serviceName: service1
servicePort: 4200
- path: /bar
backend:
serviceName: service2
servicePort: 8080
```
- route to sub domain with multiple services
```yaml
spec:
rules:
- host: foo.bar.com
http:
paths:
- backend:
serviceName: service1
servicePort: 80
- host: bar.foo.com
http:
paths:
- backend:
serviceName: service2
servicePort: 80
```
### State Persistence
- spec.volumes
- spec.volumes.hostPath.path
- spec.containers.volumeMounts
- kind: PersistentVolume(v1)
- spec.accessModes
- capacity.storage
- kind: PersistentVolumeClaim(v1)
- or use it in the pod, spec.volumes.persistentVolumeClaim.claimName
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