如何知道 CoreDNS 在 kubernetes pod 中生效
how to know the CoreDNS take effect in kubernetes pod
我正在部署 coredns（运行 在 node-01 中）：
{
"kind": "Deployment",
"apiVersion": "extensions/v1beta1",
"metadata": {
"name": "coredns",
"namespace": "kube-system",
"selfLink": "/apis/extensions/v1beta1/namespaces/kube-system/deployments/coredns",
"uid": "5d470d90-6cdf-4ef1-be00-6774d70fcb54",
"resourceVersion": "14708222",
"generation": 18,
"creationTimestamp": "2019-09-22T06:28:28Z",
"labels": {
"addonmanager.kubernetes.io/mode": "Reconcile",
"k8s-app": "kube-dns",
"kubernetes.io/cluster-service": "true",
"kubernetes.io/name": "CoreDNS"
},
"annotations": {
"deployment.kubernetes.io/revision": "6"
}
},
"spec": {
"replicas": 1,
"selector": {
"matchLabels": {
"k8s-app": "kube-dns"
}
},
"template": {
"metadata": {
"creationTimestamp": null,
"labels": {
"k8s-app": "kube-dns"
},
"annotations": {
"seccomp.security.alpha.kubernetes.io/pod": "docker/default"
}
},
"spec": {
"volumes": [
{
"name": "config-volume",
"configMap": {
"name": "coredns",
"items": [
{
"key": "Corefile",
"path": "Corefile"
}
],
"defaultMode": 420
}
}
],
"containers": [
{
"name": "coredns",
"image": "gcr.azk8s.cn/google-containers/coredns:1.3.1",
"args": [
"-conf",
"/etc/coredns/Corefile"
],
"ports": [
{
"name": "dns",
"containerPort": 53,
"protocol": "UDP"
},
{
"name": "dns-tcp",
"containerPort": 53,
"protocol": "TCP"
},
{
"name": "metrics",
"containerPort": 9153,
"protocol": "TCP"
}
],
"resources": {
"limits": {
"memory": "70Mi"
},
"requests": {
"cpu": "100m",
"memory": "70Mi"
}
},
"volumeMounts": [
{
"name": "config-volume",
"readOnly": true,
"mountPath": "/etc/coredns"
}
],
"livenessProbe": {
"httpGet": {
"path": "/health",
"port": 8080,
"scheme": "HTTP"
},
"initialDelaySeconds": 60,
"timeoutSeconds": 5,
"periodSeconds": 10,
"successThreshold": 1,
"failureThreshold": 5
},
"readinessProbe": {
"httpGet": {
"path": "/health",
"port": 8080,
"scheme": "HTTP"
},
"timeoutSeconds": 1,
"periodSeconds": 10,
"successThreshold": 1,
"failureThreshold": 3
},
"terminationMessagePath": "/dev/termination-log",
"terminationMessagePolicy": "File",
"imagePullPolicy": "IfNotPresent",
"securityContext": {
"capabilities": {
"add": [
"NET_BIND_SERVICE"
],
"drop": [
"all"
]
},
"readOnlyRootFilesystem": true,
"allowPrivilegeEscalation": false
}
}
],
"restartPolicy": "Always",
"terminationGracePeriodSeconds": 30,
"dnsPolicy": "Default",
"nodeSelector": {
"beta.kubernetes.io/os": "linux"
},
"serviceAccountName": "coredns",
"serviceAccount": "coredns",
"securityContext": {},
"schedulerName": "default-scheduler",
"tolerations": [
{
"key": "CriticalAddonsOnly",
"operator": "Exists"
}
],
"priorityClassName": "system-cluster-critical"
}
},
"strategy": {
"type": "RollingUpdate",
"rollingUpdate": {
"maxUnavailable": 1,
"maxSurge": "25%"
}
},
"revisionHistoryLimit": 10,
"progressDeadlineSeconds": 600
},
"status": {
"observedGeneration": 18,
"replicas": 1,
"updatedReplicas": 1,
"readyReplicas": 1,
"availableReplicas": 1,
"conditions": [
{
"type": "Available",
"status": "True",
"lastUpdateTime": "2019-09-22T06:28:28Z",
"lastTransitionTime": "2019-09-22T06:28:28Z",
"reason": "MinimumReplicasAvailable",
"message": "Deployment has minimum availability."
},
{
"type": "Progressing",
"status": "True",
"lastUpdateTime": "2020-02-12T14:54:06Z",
"lastTransitionTime": "2020-01-23T16:14:05Z",
"reason": "NewReplicaSetAvailable",
"message": "ReplicaSet \"coredns-89764d78c\" has successfully progressed."
}
],
"collisionCount": 1
}
}
当我从 pods（node-01 中的 运行）ping 域时，它失败了：
# access external domain
/ # ping baidu.com
ping: bad address 'baidu.com'
# access oneself
/ # ping eureka-0
PING eureka-0 (172.30.208.2): 56 data bytes
64 bytes from 172.30.208.2: seq=0 ttl=64 time=0.054 ms
# access other pod
/ # ping zuul-service
ping: bad address 'zuul-service'
我想在 node-01 的 pod 中安装 curl:
/ # apk add curl
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/main/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.9/main: temporary error (try again later)
WARNING: Ignoring APKINDEX.b89edf6e.tar.gz: No such file or directory
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/community/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.9/community: temporary error (try again later)
WARNING: Ignoring APKINDEX.737f7e01.tar.gz: No such file or directory
ERROR: unsatisfiable constraints:
curl (missing):
required by: world[curl]
当我在 Node-03 中执行这个命令时，它起作用了fine.what我应该怎么做才能找出哪里出了问题？
[root@ops001 ~]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE
coredns-89764d78c-zmz27 1/1 Running 0 90m
这是 kubernetes 版本：
[root@ops001 ~]# kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
azshara-k8s01 Ready <none> 144d v1.15.2 172.19.104.231 <none> CentOS Linux 7 (Core) 3.10.0-957.5.1.el7.x86_64 docker://19.3.1
azshara-k8s02 Ready <none> 144d v1.15.2 172.19.104.230 <none> CentOS Linux 7 (Core) 3.10.0-957.5.1.el7.x86_64 docker://18.9.6
azshara-k8s03 Ready <none> 144d v1.15.2 172.19.150.82 <none> CentOS Linux 7 (Core) 3.10.0-957.5.1.el7.x86_64 docker://18.9.6
如我所见，您正在为 docker 容器使用 openjdk:8-jre-alpine，因此：
使用此命令行进行安装：
RUN apk update 首先或
删除缓存：
RUN rm -rf /var/cache/apk/* && \
rm -rf /tmp/*
RUN apk --no-cache add curl 替换为 apk add curl
我正在部署 coredns（运行 在 node-01 中）：
{
"kind": "Deployment",
"apiVersion": "extensions/v1beta1",
"metadata": {
"name": "coredns",
"namespace": "kube-system",
"selfLink": "/apis/extensions/v1beta1/namespaces/kube-system/deployments/coredns",
"uid": "5d470d90-6cdf-4ef1-be00-6774d70fcb54",
"resourceVersion": "14708222",
"generation": 18,
"creationTimestamp": "2019-09-22T06:28:28Z",
"labels": {
"addonmanager.kubernetes.io/mode": "Reconcile",
"k8s-app": "kube-dns",
"kubernetes.io/cluster-service": "true",
"kubernetes.io/name": "CoreDNS"
},
"annotations": {
"deployment.kubernetes.io/revision": "6"
}
},
"spec": {
"replicas": 1,
"selector": {
"matchLabels": {
"k8s-app": "kube-dns"
}
},
"template": {
"metadata": {
"creationTimestamp": null,
"labels": {
"k8s-app": "kube-dns"
},
"annotations": {
"seccomp.security.alpha.kubernetes.io/pod": "docker/default"
}
},
"spec": {
"volumes": [
{
"name": "config-volume",
"configMap": {
"name": "coredns",
"items": [
{
"key": "Corefile",
"path": "Corefile"
}
],
"defaultMode": 420
}
}
],
"containers": [
{
"name": "coredns",
"image": "gcr.azk8s.cn/google-containers/coredns:1.3.1",
"args": [
"-conf",
"/etc/coredns/Corefile"
],
"ports": [
{
"name": "dns",
"containerPort": 53,
"protocol": "UDP"
},
{
"name": "dns-tcp",
"containerPort": 53,
"protocol": "TCP"
},
{
"name": "metrics",
"containerPort": 9153,
"protocol": "TCP"
}
],
"resources": {
"limits": {
"memory": "70Mi"
},
"requests": {
"cpu": "100m",
"memory": "70Mi"
}
},
"volumeMounts": [
{
"name": "config-volume",
"readOnly": true,
"mountPath": "/etc/coredns"
}
],
"livenessProbe": {
"httpGet": {
"path": "/health",
"port": 8080,
"scheme": "HTTP"
},
"initialDelaySeconds": 60,
"timeoutSeconds": 5,
"periodSeconds": 10,
"successThreshold": 1,
"failureThreshold": 5
},
"readinessProbe": {
"httpGet": {
"path": "/health",
"port": 8080,
"scheme": "HTTP"
},
"timeoutSeconds": 1,
"periodSeconds": 10,
"successThreshold": 1,
"failureThreshold": 3
},
"terminationMessagePath": "/dev/termination-log",
"terminationMessagePolicy": "File",
"imagePullPolicy": "IfNotPresent",
"securityContext": {
"capabilities": {
"add": [
"NET_BIND_SERVICE"
],
"drop": [
"all"
]
},
"readOnlyRootFilesystem": true,
"allowPrivilegeEscalation": false
}
}
],
"restartPolicy": "Always",
"terminationGracePeriodSeconds": 30,
"dnsPolicy": "Default",
"nodeSelector": {
"beta.kubernetes.io/os": "linux"
},
"serviceAccountName": "coredns",
"serviceAccount": "coredns",
"securityContext": {},
"schedulerName": "default-scheduler",
"tolerations": [
{
"key": "CriticalAddonsOnly",
"operator": "Exists"
}
],
"priorityClassName": "system-cluster-critical"
}
},
"strategy": {
"type": "RollingUpdate",
"rollingUpdate": {
"maxUnavailable": 1,
"maxSurge": "25%"
}
},
"revisionHistoryLimit": 10,
"progressDeadlineSeconds": 600
},
"status": {
"observedGeneration": 18,
"replicas": 1,
"updatedReplicas": 1,
"readyReplicas": 1,
"availableReplicas": 1,
"conditions": [
{
"type": "Available",
"status": "True",
"lastUpdateTime": "2019-09-22T06:28:28Z",
"lastTransitionTime": "2019-09-22T06:28:28Z",
"reason": "MinimumReplicasAvailable",
"message": "Deployment has minimum availability."
},
{
"type": "Progressing",
"status": "True",
"lastUpdateTime": "2020-02-12T14:54:06Z",
"lastTransitionTime": "2020-01-23T16:14:05Z",
"reason": "NewReplicaSetAvailable",
"message": "ReplicaSet \"coredns-89764d78c\" has successfully progressed."
}
],
"collisionCount": 1
}
}
当我从 pods（node-01 中的 运行）ping 域时，它失败了：
# access external domain
/ # ping baidu.com
ping: bad address 'baidu.com'
# access oneself
/ # ping eureka-0
PING eureka-0 (172.30.208.2): 56 data bytes
64 bytes from 172.30.208.2: seq=0 ttl=64 time=0.054 ms
# access other pod
/ # ping zuul-service
ping: bad address 'zuul-service'
我想在 node-01 的 pod 中安装 curl:
/ # apk add curl
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/main/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.9/main: temporary error (try again later)
WARNING: Ignoring APKINDEX.b89edf6e.tar.gz: No such file or directory
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/community/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.9/community: temporary error (try again later)
WARNING: Ignoring APKINDEX.737f7e01.tar.gz: No such file or directory
ERROR: unsatisfiable constraints:
curl (missing):
required by: world[curl]
当我在 Node-03 中执行这个命令时，它起作用了fine.what我应该怎么做才能找出哪里出了问题？
[root@ops001 ~]# kubectl get pods --namespace=kube-system -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE
coredns-89764d78c-zmz27 1/1 Running 0 90m
这是 kubernetes 版本：
[root@ops001 ~]# kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
azshara-k8s01 Ready <none> 144d v1.15.2 172.19.104.231 <none> CentOS Linux 7 (Core) 3.10.0-957.5.1.el7.x86_64 docker://19.3.1
azshara-k8s02 Ready <none> 144d v1.15.2 172.19.104.230 <none> CentOS Linux 7 (Core) 3.10.0-957.5.1.el7.x86_64 docker://18.9.6
azshara-k8s03 Ready <none> 144d v1.15.2 172.19.150.82 <none> CentOS Linux 7 (Core) 3.10.0-957.5.1.el7.x86_64 docker://18.9.6
如我所见，您正在为 docker 容器使用 openjdk:8-jre-alpine，因此：
使用此命令行进行安装：
RUN apk update 首先或
删除缓存：
RUN rm -rf /var/cache/apk/* && \
rm -rf /tmp/*
RUN apk --no-cache add curl 替换为 apk add curl