我有两个应用，nginx和redis，其中nginx使用redis缓存一些数据，所以在nginx中必须配置redis地址。
一方面，我可以先应用 redis 部署并获取其 IP，然后应用 nginx 部署在我的minikube中设置两个应用程序。
但另一方面，为了简化在Kubernetes Dashboard中进行 QA 的安装，我想创建一个 Kubernetes YAML 文件（如GoogleCloudPlatform/microservices-demo/kubernetes-manifests.yaml）来将这两个应用程序部署在两个不同的Pod上。但是，如果我通过Environment Variables执行此操作，则无法获取 redis 地址。
那么我该如何实现呢？
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis-master
labels:
app: redis
spec:
selector:
matchLabels:
app: redis
role: master
tier: backend
replicas: 2
template:
metadata:
labels:
app: redis
role: master
tier: backend
spec:
containers:
- name: master-c
image: docker.io/redis:alpine
ports:
- containerPort: 6379
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-nginx
spec:
selector: # Defines how the Deployment finds which Pods to manage.
matchLabels:
app: my-nginx
template:
metadata: # Defines what the newly created Pods are labeled.
labels:
app: my-nginx
tier: frontend
spec:
terminationGracePeriodSeconds: 5
containers:
- name: my-nginx # Defines container name
image: my-nginx:dev # docker image load -i my-nginx-docker_image.tar
imagePullPolicy: Never # Always, IfNotPresent (default), Never
ports:
env:
- name: NGINX_ERROR_LOG_SEVERITY_LEVEL
value: debug
- name: MY_APP_REDIS_HOST
# How to use the IP address of the POD with redis-master labeled that is created by the previous deployment?
value: 10.86.50.235
# https://kubernetes.io/docs/tasks/inject-data-application/environment-variable-expose-pod-information/
# valueFrom:
# fieldRef:
# fieldPath: status.podIP # this is the current POD IP
- name: MY_APP_CLIENT_ID
value: client_id
- name: MY_APP_CLIENT_SECRET
# https://kubernetes.io/docs/concepts/configuration/secret
value: client_secret
---
# https://kubernetes.io/docs/concepts/services-networking/service/#defining-a-service
apiVersion: v1
kind: Service
# https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
# https://kubernetes.io/docs/concepts/overview/working-with-objects/field-selectors/
# metadata - Data that helps uniquely identify the object, including a name string, UID, and optional namespace
metadata:
name: my-nginx
spec:
type: NodePort
selector:
# Defines a proper selector for your pods with corresponding `.metadata.labels` field.
# Verify it using: kubectl get pods --selector app=my-nginx || kubectl get pod -l app=my-nginx
# Make sure the service points to correct pod by, for example, `kubectl describe pod -l app=my-nginx`
app: my-nginx
ports:
# By default and for convenience, the `targetPort` is set to the same value as the `port` field.
- name: http
port: 6080
targetPort: 80
# By default and for convenience, the Kubernetes control plane will allocate a port from a range (default: 30000-32767)
nodePort: 30080
- name: https
port: 6443
targetPort: 443
nodePort: 30443
添加了一些网络输出，
Microsoft Windows [Version 10.0.18362.900]
(c) 2019 Microsoft Corporation. All rights reserved.
PS C:\Users\ssfang> kubectl get pods
NAME READY STATUS RESTARTS AGE
my-nginx-pod 1/1 Running 9 5d14h
redis-master-7db899bccb-npl6s 1/1 Running 3 2d15h
redis-master-7db899bccb-rgx47 1/1 Running 3 2d15h
C:\Users\ssfang> kubectl exec redis-master-7db899bccb-npl6s -- cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5
C:\Users\ssfang> kubectl exec my-nginx-pod -- cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5
C:\Users\ssfang> kubectl -n kube-system get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx-controller-admission ClusterIP 10.108.221.2 <none> 443/TCP 7d11h
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 7d17h
C:\Users\ssfang> kubectl get ep kube-dns --namespace=kube-system
NAME ENDPOINTS AGE
kube-dns 172.17.0.2:53,172.17.0.5:53,172.17.0.2:9153 + 3 more... 7d17h
C:\Users\ssfang> kubectl get ep kube-dns --namespace=kube-system -o=yaml
apiVersion: v1
kind: Endpoints
metadata:
annotations:
endpoints.kubernetes.io/last-change-trigger-time: "2020-07-09T02:08:35Z"
creationTimestamp: "2020-07-01T09:34:44Z"
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: KubeDNS
managedFields:
- apiVersion: v1
fieldsType: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.: {}
f:endpoints.kubernetes.io/last-change-trigger-time: {}
f:labels:
.: {}
f:k8s-app: {}
f:kubernetes.io/cluster-service: {}
f:kubernetes.io/name: {}
f:subsets: {}
manager: kube-controller-manager
operation: Update
time: "2020-07-09T02:08:35Z"
name: kube-dns
namespace: kube-system
resourceVersion: "523617"
selfLink: /api/v1/namespaces/kube-system/endpoints/kube-dns
subsets:
- addresses:
nodeName: minikube
targetRef:
kind: Pod
namespace: kube-system
resourceVersion: "523566"
uid: ed3a9f46-718a-477a-8804-e87511db16d1
- ip: 172.17.0.5
nodeName: minikube
targetRef:
kind: Pod
name: coredns-546565776c-hmm5s
namespace: kube-system
resourceVersion: "523616"
uid: ae21c65c-e937-4e3d-8a7a-636d4f780855
ports:
- name: dns-tcp
port: 53
protocol: TCP
- name: metrics
port: 9153
protocol: TCP
- name: dns
port: 53
protocol: UDP
C:\Users\ssfang> kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d20h
my-nginx-service NodePort 10.98.82.96 <none> 6080:30080/TCP,6443:30443/TCP 7d13h
PS C:\Users\ssfang> kubectl describe pod/my-nginx-pod | findstr IP
IP: 172.17.0.8
IPs:
IP: 172.17.0.8
PS C:\Users\ssfang> kubectl describe service/my-nginx-service | findstr IP
IP: 10.98.82.96
C:\Users\ssfang> kubectl describe pod/my-nginx-65ffdfb5b5-dzgjk | findstr IP
IP: 172.17.0.4
IPs:
IP: 172.17.0.4
以两个带有 nginx 的 Pod 为例来检查网络，
- C:\Users\ssfang> kubectl exec my-nginx-pod -it -- bash
# How to install nslookup, dig, host commands in Linux
apt-get install dnsutils -y # In ubuntu
yum install bind-utils -y # In RHEL/Centos
root@my-nginx-pod:/etc# apt update && apt-get install -y dnsutils iputils-ping
root@my-nginx-pod:/etc# nslookup my-nginx-service
Server: 10.96.0.10
Address: 10.96.0.10#53
Name: my-nginx-service.default.svc.cluster.local
Address: 10.98.82.96
root@my-nginx-pod:/etc# nslookup my-nginx-pod
Server: 10.96.0.10
Address: 10.96.0.10#53
** server can't find my-nginx-pod: SERVFAIL
root@my-nginx-pod:/etc# ping -c3 -W60 my-nginx-pod
PING my-nginx-pod (172.17.0.8) 56(84) bytes of data.
64 bytes from my-nginx-pod (172.17.0.8): icmp_seq=1 ttl=64 time=0.011 ms
64 bytes from my-nginx-pod (172.17.0.8): icmp_seq=2 ttl=64 time=0.021 ms
64 bytes from my-nginx-pod (172.17.0.8): icmp_seq=3 ttl=64 time=0.020 ms
--- my-nginx-pod ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2065ms
rtt min/avg/max/mdev = 0.011/0.017/0.021/0.005 ms
root@my-nginx-pod:/etc# ping -c3 -W20 my-nginx-service
PING my-nginx-service.default.svc.cluster.local (10.98.82.96) 56(84) bytes of data.
--- my-nginx-service.default.svc.cluster.local ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2060ms
root@my-nginx-pod:/etc# ping -c3 -W20 my-nginx-pod.default.svc.cluster.local
ping: my-nginx-pod.default.svc.cluster.local: Name or service not known
root@my-nginx-pod:/etc# ping -c3 -W20 my-nginx-service.default.svc.cluster.local
PING my-nginx-service.default.svc.cluster.local (10.98.82.96) 56(84) bytes of data.
--- my-nginx-service.default.svc.cluster.local ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2051ms
- C:\Users\ssfang> kubectl exec my-nginx-65ffdfb5b5-dzgjk -it -- bash
root@my-nginx-65ffdfb5b5-dzgjk:/etc# ping -c3 -W20 my-nginx-pod.default.svc.cluster.local
ping: my-nginx-pod.default.svc.cluster.local: Name or service not known
root@my-nginx-65ffdfb5b5-dzgjk:/etc# ping -c3 -W20 my-nginx-service.default.svc.cluster.local
ping: my-nginx-service.default.svc.cluster.local: Name or service not known
root@my-nginx-65ffdfb5b5-dzgjk:/etc# ping -c3 -W20 172.17.0.8
PING 172.17.0.8 (172.17.0.8) 56(84) bytes of data.
64 bytes from 172.17.0.8: icmp_seq=1 ttl=64 time=0.195 ms
64 bytes from 172.17.0.8: icmp_seq=2 ttl=64 time=0.039 ms
64 bytes from 172.17.0.8: icmp_seq=3 ttl=64 time=0.039 ms
--- 172.17.0.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2055ms
rtt min/avg/max/mdev = 0.039/0.091/0.195/0.073 ms
- C:\Users\ssfang> ssh -o StrictHostKeyChecking=no -i C:\Users\ssfang.minikube\machines\minikube\id_rsa docker@10.86.50.252 &:: minikube ssh
_ _
_ _ ( ) ( )
___ ___ (_) ___ (_)| |/') _ _ | |_ __
/' _ ` _ `\| |/' _ `\| || , < ( ) ( )| '_`\ /'__`\
| ( ) ( ) || || ( ) || || |\`\ | (_) || |_) )( ___/
(_) (_) (_)(_)(_) (_)(_)(_) (_)`\___/'(_,__/'`\____)
$ ping default.svc.cluster.local
ping: bad address 'default.svc.cluster.local'
$ ping my-nginx-pod.default.svc.cluster.local
ping: bad address 'my-nginx-pod.default.svc.cluster.local'
$ ping my-nginx-service.default.svc.cluster.local
ping: bad address 'my-nginx-service.default.svc.cluster.local'
$ nslookup whoami
Server: 10.86.50.1
Address: 10.86.50.1:53
** server can't find whoami: NXDOMAIN
** server can't find whoami: NXDOMAIN
$ ping -c3 -W20 172.17.0.8
PING 172.17.0.8 (172.17.0.8): 56 data bytes
64 bytes from 172.17.0.8: seq=0 ttl=64 time=0.053 ms
64 bytes from 172.17.0.8: seq=1 ttl=64 time=0.035 ms
64 bytes from 172.17.0.8: seq=2 ttl=64 time=0.040 ms
--- 172.17.0.8 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.035/0.042/0.053 ms
$ ping -c3 -W20 172.17.0.4
PING 172.17.0.4 (172.17.0.4): 56 data bytes
64 bytes from 172.17.0.4: seq=0 ttl=64 time=0.070 ms
64 bytes from 172.17.0.4: seq=1 ttl=64 time=0.039 ms
64 bytes from 172.17.0.4: seq=2 ttl=64 time=0.038 ms
--- 172.17.0.4 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.038/0.049/0.070 ms