07. Networking
01. Explore Environment
02. CNI weave
03. Deploy Network Solution
04. Networking Weave
05. Service Networking
06. CoreDNS in Kubernetes
07. CKA – Ingress Networking – 1
08. CKA – Ingress Networking – 2
root@controlplane:~# k describe deployment.apps/coredns -n kube-system
Name: coredns
Namespace: kube-system
CreationTimestamp: Thu, 03 Feb 2022 01:55:46 +0000
Labels: k8s-app=kube-dns
Annotations: deployment.kubernetes.io/revision: 1
Selector: k8s-app=kube-dns
Replicas: 2 desired | 2 updated | 2 total | 2 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 1 max unavailable, 25% max surge
Pod Template:02. How many pods of the DNS server are deployed?
ask :) 2
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/coredns 2/2 2 2 13m
03. What is the name of the service created for accessing CoreDNS?
ask : kube-dns
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 15m
04. What is the IP of the CoreDNS server that should be configured on PODs to resolve services?
서비스를 해결하기 위해 POD에서 구성해야 하는 CoreDNS 서버의 IP는 무엇입니까?
ask : 10.96.0.10
service 의 클러스터 ip 가 10.96.0.10 이었음.
05. Where is the configuration file located for configuring the CoreDNS service?
ask : /etc/coredns/Corefile
root@controlplane:~# k describe deployment.apps/coredns -n kube-system
Name: coredns
Namespace: kube-system
CreationTimestamp: Thu, 03 Feb 2022 01:55:46 +0000
Labels: k8s-app=kube-dns
Annotations: deployment.kubernetes.io/revision: 1
Selector: k8s-app=kube-dns
Replicas: 2 desired | 2 updated | 2 total | 2 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 1 max unavailable, 25% max surge
Pod Template:
Labels: k8s-app=kube-dns
Service Account: coredns
Containers:
coredns:
Image: k8s.gcr.io/coredns:1.7.0
Ports: 53/UDP, 53/TCP, 9153/TCP
Host Ports: 0/UDP, 0/TCP, 0/TCP
Args:
-conf
/etc/coredns/Corefile
Limits:
memory: 170Mi
Requests:
cpu: 100m
memory: 70Mi
Liveness: http-get http://:8080/health delay=60s timeout=5s period=10s #success=1 #failure=5
Readiness: http-get http://:8181/ready delay=0s timeout=1s period=10s #success=1 #failure=3
Environment: <none>
Mounts:
/etc/coredns from config-volume (ro)
Volumes:
config-volume:
Type: ConfigMap (a volume populated by a ConfigMap)
Name: coredns
Optional: false
Priority Class Name: system-cluster-critical
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: coredns-74ff55c5b (2/2 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 16m deployment-controller Scaled up replica set coredns-74ff55c5b to 2
06. How is the Corefile passed in to the CoreDNS POD?
Corefile은 CoreDNS POD에 어떻게 전달됩니까?
1) Stored on the kube master
2) pulled from git
3) Configured as a ConfigMap object
4) Corefile comes built-in with CoreDNS pod
root@controlplane:~# kubectl get configmap
NAME DATA AGE
kube-root-ca.crt 1 19mUse the kubectl get configmap command for
kube-system namespace and inspect the correct ConfigMap.
07. What is the name of the ConfigMap object created for Corefile?
1) dns-config
2) corefile-config
3) coredns
4) kube-proxy
root@controlplane:~# k get cm -n kube-system
NAME DATA AGE
coredns 1 23m
extension-apiserver-authentication 6 24m
kube-flannel-cfg 2 23m
kube-proxy 2 23m
kube-root-ca.crt 1 23m
kubeadm-config 2 23m
kubelet-config-1.20 1 23m
08. What is the root domain/zone configured for this kubernetes cluster?
ask : cluster.local
networking:
dnsDomain: cluster.local
podSubnet: 10.244.0.0/16
serviceSubnet: 10.96.0.0/12
info
09. We have deployed a set of PODs and Services in the default and payroll namespaces.
Inspect them and go to the next question.
기본 및 급여 네임스페이스에 POD 및 서비스 세트를 배포했습니다.
그것들을 조사하고 다음 질문으로 가십시오.
Ok
10. What name can be used to access the hr web server from the test Application?
You can execute a curl command on the test pod to test.
Alternatively, the test Application also has a UI.
Access it using the tab at the top of your terminal named test-app.
테스트 응용 프로그램에서 hr 웹 서버에 액세스하는 데 사용할 수 있는 이름은 무엇입니까?
테스트할 테스트 포드에서 curl 명령을 실행할 수 있습니다.
또는 테스트 애플리케이션에도 UI가 있습니다.
test-app이라는 터미널 상단의 탭을 사용하여 액세스하십시오.
1) web-service
2) test-service
3) web
4) web-service.payroll
11. Which of the names CANNOT be used to access the HR service from the test pod?
테스트 포드에서 HR 서비스에 액세스하는 데 사용할 수 없는 이름은 무엇입니까?
1) web-service.default
2) web-service
3) web-service.default.svc
4) web-service.default.pod
12. Which of the below name can be used to access the payroll service from the test application?
테스트 애플리케이션에서 급여 서비스에 액세스하는 데 사용할 수 있는 이름은 다음 중 무엇입니까?
1) web
2) web-service.default
3) web-service.payroll
4) web-service
root@controlplane:~# k get svc --all-namespaces
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
default kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 35m
default test-service NodePort 10.101.148.120 <none> 80:30080/TCP 27m
default web-service ClusterIP 10.111.195.66 <none> 80/TCP 27m
kube-system kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 35m
payroll web-service ClusterIP 10.106.241.53 <none> 80/TCP 27m
13. Which of the below name CANNOT be used to access the payroll service from the test application?
테스트 애플리케이션에서 급여 서비스에 액세스하는 데 사용할 수 없는 이름은 다음 중 무엇입니까?
1) web-service.payroll.svc.cluster.local
2) web-service.payroll.svc
3) web-service.payroll.svc.cluster
4) web-service.payroll
14. We just deployed a web server - webapp - that accesses a database mysql - server.
However the web server is failing to connect to the database server. Troubleshoot and fix the issue.
데이터베이스 mysql에 액세스하는 웹 서버(webapp)를 방금 배포했습니다.
그러나 웹 서버는 데이터베이스 서버에 연결하는 데 실패합니다. 문제를 해결하고 수정합니다.
They could be in different namespaces.
First locate the applications.
The web server interface can be seen by clicking the tab Web Server at the top of your terminal.
다른 네임스페이스에 있을 수 있습니다.
먼저 응용 프로그램을 찾습니다.
웹 서버 인터페이스는 터미널 상단의 웹 서버 탭을 클릭하여 볼 수 있습니다.
- Web Server: webapp
- Uses the right DB_Host name
mysql >> mysql.payroll
apiVersion: apps/v1
kind: Deployment
metadata:
name: webapp
labels:
name: webapp
spec:
selector:
matchLabels:
name: webapp
template:
metadata:
labels:
name: webapp
spec:
containers:
- name: simple-webapp-mysql
image: mmumshad/simple-webapp-mysql
ports:
- containerPort: 8080
env:
- name: DB_Host
value: mysql.payroll
- name: DB_User
value: root
- name: DB_Password
value: paswrd
---
kind: Service
apiVersion: v1
metadata:
name: webapp-service
spec:
selector:
name: webapp
type: NodePort
ports:
- port: 8080
targetPort: 8080
15. From the hr pod nslookup the mysql service and redirect the output to a file /root/CKA/nslookup.out
hr pod nslookup mysql 서비스에서 출력을 /root/CKA/nslookup.out 파일로 리디렉션합니다.
- nslookup output redirected
Run the command:
kubectl exec -it hr -- nslookup mysql.payroll > /root/CKA/nslookup.outhttps://kubernetes.io/ko/docs/tasks/administer-cluster/coredns/
서비스 디스커버리를 위해 CoreDNS 사용하기
이 페이지는 CoreDNS 업그레이드 프로세스와 kube-dns 대신 CoreDNS를 설치하는 방법을 보여준다. 시작하기 전에 쿠버네티스 클러스터가 필요하고, kubectl 커맨드-라인 툴이 클러스터와 통신할 수 있도
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