Kubernetes（k8s）安装dns附件组件以及使用
2021-02-02 05:16
标签：pen namespace guarantee ant int 机制 三台 bee release 1、K8s附加组件DNS服务。 答：Kubernetes中有一个很重要的特性，服务子发现。一旦一个service被创建，该service的service ip和service port等信息都可以被注入到pod中供它们使用。kubernetes主要支持两种service发现机制，第一种是环境变量，第二种是DNS。没有dns服务的时候，kubernetes会采用环境变量的形式，一个有很多service，环境变量会变得很复杂，为了解决这个问题，我们使用DNS服务。 2、Pod的环境变量如何查看呢？ 如果有几个Service就会有几个环境变量，这里进行简单的过滤。 如果环境变量过多的话，会变得很复杂，所以引入了DNS服务。 3、下载DNS的资料包，如下所示： 修改skydns-rc.yaml配置文件。 需要将此地址的ip地址修改为自己api-server的地址。 开始创建RC，创建需要很长时间的。 开始创建SVC，修改配置文件，使用kubectl get svc查看CLUSTER-IP的地址，只要未被使用，就可以配置到skydns-svc.yaml 配置文件中即可。 创建svc的命令，如下所示： 根据命名空间来查看创建好的pod，可以看到这个Pod里面的四个容器都已经运行起来了。 如果希望所有的Pod都使用DNS的话，还需要修改一下配置文件。修改kubelet配置，修改各个node节点上的/etc/kubernetes/kubelet配置文件，增加如下行。然后再重启各个node节点的kubelet。 4、修改kubelet配置，修改各个node节点上的/etc/kubernetes/kubelet配置文件，增加如下行。然后再重启各个node节点的kubelet。 这个地址就是刚才自己配置的svc的地址，可以使用命令进行查看。 然后重启三台Node节点的kubelet服务。 如何测试DNS是否生效呢，可以使用下面的配置进行测试。 可以检测一下，svc的vip是否可以解析出来。 可以看出来和SVC的地址一样。 注意，刚才创建的dns服务，只有新起的pod里面才可以使用，如果已经存在的pod里面还没有使用dns服务的。如果想要之前的pod使用dns服务，需要将他们删除掉，重新创建一下的。 备注：如果配置好了DNS之后，创建的RC里面就可以不使用环境变量的地址（即VIP的地址），可以使用service（svc）的名称既可以找到这个service。 Kubernetes（k8s）安装dns附件组件以及使用 标签：pen namespace guarantee ant int 机制 三台 bee release 原文地址：https://www.cnblogs.com/biehongli/p/13156981.html 1 [root@k8s-master ~]# kubectl get all -o wide
2 NAME DESIRED CURRENT READY AGE CONTAINER(S) IMAGE(S) SELECTOR
3 rc/mysql 1 1 1 16h mysql 192.168.110.133:5000/mysql:5.7.30 app=mysql
4 rc/myweb 1 1 1 1h myweb 192.168.110.133:5000/tomcat:latest app=myweb
5
6 NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
7 svc/kubernetes 10.254.0.1
1 root@myweb-hsdwn:/usr/local/tomcat# env | grep -iE ‘kubernetes|mysql|myweb‘
2 KUBERNETES_SERVICE_PORT_HTTPS=443
3 MYSQL_PORT=tcp://10.254.207.238:3306
4 MYSQL_PORT_3306_TCP_ADDR=10.254.207.238
5 KUBERNETES_SERVICE_PORT=443
6 MYSQL_PORT_3306_TCP_PORT=3306
7 HOSTNAME=myweb-hsdwn
8 MYSQL_PORT_3306_TCP=tcp://10.254.207.238:3306
9 KUBERNETES_PORT_443_TCP=tcp://10.254.0.1:443
10 MYSQL_SERVICE_PORT=3306
11 MYSQL_SERVICE_HOST=10.254.207.238
12 MYSQL_PORT_3306_TCP_PROTO=tcp
13 KUBERNETES_PORT_443_TCP_PROTO=tcp
14 KUBERNETES_PORT_443_TCP_ADDR=10.254.0.1
15 KUBERNETES_SERVICE_HOST=10.254.0.1
16 KUBERNETES_PORT=tcp://10.254.0.1:443
17 KUBERNETES_PORT_443_TCP_PORT=443
18 root@myweb-hsdwn:/usr/local/tomcat#
1 root@myweb-hsdwn:/usr/local/tomcat# env | grep -iE ‘kubernetes|mysql|myweb‘ | wc -l
2 16
3 root@myweb-hsdwn:/usr/local/tomcat#
1 [root@k8s-master tomcat_demo]# wget https://www.qstack.com.cn/skydns.zip
2 --2020-06-18 15:31:25-- https://www.qstack.com.cn/skydns.zip
3 Resolving www.qstack.com.cn (www.qstack.com.cn)... 123.125.46.149, 111.202.85.37
4 Connecting to www.qstack.com.cn (www.qstack.com.cn)|123.125.46.149|:443... connected.
5 HTTP request sent, awaiting response... 200 OK
6 Length: 3411 (3.3K) [application/zip]
7 Saving to: ‘skydns.zip’
8
9 100%[======================================================================================>] 3,411 --.-K/s in 0s
10
11 2020-06-18 15:31:26 (40.5 MB/s) - ‘skydns.zip’ saved [3411/3411]
12
13 [root@k8s-master tomcat_demo]# ls
14 mysql-rc.yml mysql-svc.yml skydns.zip tomcat-rc.yml tomcat-svc.yml
15 [root@k8s-master tomcat_demo]# cd ..
16 [root@k8s-master k8s]# mv tomcat_demo/skydns.zip .
17 [root@k8s-master k8s]# ls
18 book-master.war deploy pod rc skydns.zip svc tomcat_demo tomcat_demo.zip
19 [root@k8s-master k8s]# unzip skydns.zip
20 Archive: skydns.zip
21 creating: skydns/
22 inflating: skydns/skydns-rc.yaml
23 inflating: skydns/skydns-svc.yaml
24 inflating: skydns/test_dns_pod.yaml
25 [root@k8s-master k8s]# ls
26 book-master.war deploy pod rc skydns skydns.zip svc tomcat_demo tomcat_demo.zip
27 [root@k8s-master k8s]#
1 # Copyright 2016 The Kubernetes Authors.
2 #
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
6 #
7 # http://www.apache.org/licenses/LICENSE-2.0
8 #
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
14
15 # TODO - At some point, we need to rename all skydns-*.yaml.* files to kubedns-*.yaml.*
16 # Should keep target in cluster/addons/dns-horizontal-autoscaler/dns-horizontal-autoscaler.yaml
17 # in sync with this file.
18
19 # __MACHINE_GENERATED_WARNING__
20
21 apiVersion: extensions/v1beta1
22 kind: Deployment
23 metadata:
24 name: kube-dns
25 namespace: kube-system
26 labels:
27 k8s-app: kube-dns
28 kubernetes.io/cluster-service: "true"
29 spec:
30 replicas: 1
31 # replicas: not specified here:
32 # 1. In order to make Addon Manager do not reconcile this replicas parameter.
33 # 2. Default is 1.
34 # 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.
35 strategy:
36 rollingUpdate:
37 maxSurge: 10%
38 maxUnavailable: 0
39 selector:
40 matchLabels:
41 k8s-app: kube-dns
42 template:
43 metadata:
44 labels:
45 k8s-app: kube-dns
46 annotations:
47 scheduler.alpha.kubernetes.io/critical-pod: ‘‘
48 scheduler.alpha.kubernetes.io/tolerations: ‘[{"key":"CriticalAddonsOnly", "operator":"Exists"}]‘
49 spec:
50 containers:
51 - name: kubedns
52 image: myhub.fdccloud.com/library/kubedns-amd64:1.9
53 resources:
54 # TODO: Set memory limits when we‘ve profiled the container for large
55 # clusters, then set request = limit to keep this container in
56 # guaranteed class. Currently, this container falls into the
57 # "burstable" category so the kubelet doesn‘t backoff from restarting it.
58 limits:
59 memory: 170Mi
60 requests:
61 cpu: 100m
62 memory: 70Mi
63 livenessProbe:
64 httpGet:
65 path: /healthz-kubedns
66 port: 8080
67 scheme: HTTP
68 initialDelaySeconds: 60
69 timeoutSeconds: 5
70 successThreshold: 1
71 failureThreshold: 5
72 readinessProbe:
73 httpGet:
74 path: /readiness
75 port: 8081
76 scheme: HTTP
77 # we poll on pod startup for the Kubernetes master service and
78 # only setup the /readiness HTTP server once that‘s available.
79 initialDelaySeconds: 3
80 timeoutSeconds: 5
81 args:
82 - --domain=cluster.local.
83 - --dns-port=10053
84 - --config-map=kube-dns
85 - --kube-master-url=http://10.0.0.11:8080
86 # This should be set to v=2 only after the new image (cut from 1.5) has
87 # been released, otherwise we will flood the logs.
88 - --v=0
89 #__PILLAR__FEDERATIONS__DOMAIN__MAP__
90 env:
91 - name: PROMETHEUS_PORT
92 value: "10055"
93 ports:
94 - containerPort: 10053
95 name: dns-local
96 protocol: UDP
97 - containerPort: 10053
98 name: dns-tcp-local
99 protocol: TCP
100 - containerPort: 10055
101 name: metrics
102 protocol: TCP
103 - name: dnsmasq
104 image: myhub.fdccloud.com/library/kube-dnsmasq-amd64:1.4
105 livenessProbe:
106 httpGet:
107 path: /healthz-dnsmasq
108 port: 8080
109 scheme: HTTP
110 initialDelaySeconds: 60
111 timeoutSeconds: 5
112 successThreshold: 1
113 failureThreshold: 5
114 args:
115 - --cache-size=1000
116 - --no-resolv
117 - --server=127.0.0.1#10053
118 #- --log-facility=-
119 ports:
120 - containerPort: 53
121 name: dns
122 protocol: UDP
123 - containerPort: 53
124 name: dns-tcp
125 protocol: TCP
126 # see: https://github.com/kubernetes/kubernetes/issues/29055 for details
127 resources:
128 requests:
129 cpu: 150m
130 memory: 10Mi
131 - name: dnsmasq-metrics
132 image: myhub.fdccloud.com/library/dnsmasq-metrics-amd64:1.0
133 livenessProbe:
134 httpGet:
135 path: /metrics
136 port: 10054
137 scheme: HTTP
138 initialDelaySeconds: 60
139 timeoutSeconds: 5
140 successThreshold: 1
141 failureThreshold: 5
142 args:
143 - --v=2
144 - --logtostderr
145 ports:
146 - containerPort: 10054
147 name: metrics
148 protocol: TCP
149 resources:
150 requests:
151 memory: 10Mi
152 - name: healthz
153 image: myhub.fdccloud.com/library/exechealthz-amd64:1.2
154 resources:
155 limits:
156 memory: 50Mi
157 requests:
158 cpu: 10m
159 # Note that this container shouldn‘t really need 50Mi of memory. The
160 # limits are set higher than expected pending investigation on #29688.
161 # The extra memory was stolen from the kubedns container to keep the
162 # net memory requested by the pod constant.
163 memory: 50Mi
164 args:
165 - --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null
166 - --url=/healthz-dnsmasq
167 - --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1:10053 >/dev/null
168 - --url=/healthz-kubedns
169 - --port=8080
170 - --quiet
171 ports:
172 - containerPort: 8080
173 protocol: TCP
174 dnsPolicy: Default # Don‘t use cluster DNS.
1 [root@k8s-master skydns]# kubectl create -f skydns-rc.yaml
2 deployment "kube-dns" created
3 [root@k8s-master skydns]#
1 [root@k8s-master ~]# kubectl get svc
2 NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
3 kubernetes 10.254.0.1
1 [root@k8s-master skydns]# vim skydns-svc.yaml
2 [root@k8s-master skydns]# kubectl create -f skydns-svc.yaml
3 service "kube-dns" created
4 [root@k8s-master skydns]#
1 [root@k8s-master skydns]# kubectl get pod --namespace=kube-system
2 NAME READY STATUS RESTARTS AGE
3 kube-dns-778415672-f9ssw 4/4 Running 0 6m
4 [root@k8s-master skydns]#
1 [root@k8s-master skydns]# kubectl get all --namespace=kube-system
2 NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
3 deploy/kube-dns 1 1 1 1 7m
4
5 NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
6 svc/kube-dns 10.254.230.254
1 KUBELET_ARGS="--cluster_dns=10.254.230.254 --cluster_domain=cluster.local"
1 [root@k8s-master skydns]# vim /etc/kubernetes/kubelet
2 [root@k8s-master skydns]# kubectl get svc --namespace=kube-system
3 NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
4 kube-dns 10.254.230.254
1 [root@k8s-master skydns]# systemctl restart kubelet.service
2
3 [root@k8s-node2 ~]# systemctl restart kubelet.service
4
5 [root@k8s-node3 ~]# systemctl restart kubelet.service
1 [root@k8s-master skydns]# ls
2 skydns-rc.yaml skydns-svc.yaml test_dns_pod.yaml
3 [root@k8s-master skydns]# cat test_dns_pod.yaml
4 apiVersion: v1
5 kind: Pod
6 metadata:
7 labels:
8 name: busybox
9 role: master
10 name: busybox2
11 spec:
12 containers:
13 - name: busybox
14 image: docker.io/busybox:latest
15 imagePullPolicy: IfNotPresent
16 command:
17 - sleep
18 - "3600"
19 [root@k8s-master skydns]# kubectl create -f test_dns_pod.yaml
20 pod "busybox2" created
21 [root@k8s-master skydns]# kubectl get pods
22 NAME READY STATUS RESTARTS AGE
23 busybox2 1/1 Running 0 20s
24 mysql-lmx4s 1/1 Running 0 59m
25 myweb-hsdwn 1/1 Running 0 45m
26 [root@k8s-master skydns]# kubectl exec -it busybox2 sh
27 / #
1 / # nslookup mysql
2 Server: 10.254.230.254
3 Address: 10.254.230.254:53
4
5 Name: mysql.default.svc.cluster.local
6 Address: 10.254.207.238
1 [root@k8s-master ~]# kubectl get svc
2 NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
3 kubernetes 10.254.0.1
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