kube-dns deployment文件分析

[root@docker1 kubedns]# cat kubedns-controller.yaml 
# Copyright 2016 The Kubernetes Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Should keep target in cluster/addons/dns-horizontal-autoscaler/dns-horizontal-autoscaler.yaml
# in sync with this file.

# Warning: This is a file generated from the base underscore template file: kubedns-controller.yaml.base

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: kube-dns
  namespace: kube-system
  #deployment自定义标签
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
#Spec--pod详细定义
spec:
  # replicas: not specified here:
  # 1. In order to make Addon Manager do not reconcile this replicas parameter.
  # 2. Default is 1.
  # 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.
  strategy:
    rollingUpdate:
      maxSurge: 10%
      maxUnavailable: 0
  selector:
    matchLabels:
      k8s-app: kube-dns
  template:
    metadata:
      labels:
        k8s-app: kube-dns
      #自定义注解，调度中的关键pod
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"
      #pod的volume定义，提供给pod内所有container mount
      volumes:
      - name: kube-dns-config
        #使用config map配置，cm可以通过kubectl get cm -n kube-system获得
###################################################
#[root@docker1 ~]# kubectl get cm -n kube-system -o yaml
#apiVersion: v1
#items:
#- apiVersion: v1
#  kind: ConfigMap
# metadata:
#    creationTimestamp: 2017-07-09T15:07:48Z
#    labels:
#      addonmanager.kubernetes.io/mode: EnsureExists
#    name: kube-dns
#    namespace: kube-system
#    resourceVersion: "5693"
#    selfLink: /api/v1/namespaces/kube-system/configmaps/kube-dns
#    uid: 5ebf1bf0-64b8-11e7-ae06-000c29420d98
#kind: List
#resourceVersion: ""
#selfLink: ""
##################################################
        configMap:
          name: kube-dns
          optional: true
      ####开始具体容器的定义####
      containers:
      - name: kubedns
      ###kubedns容器负责和k8s API接口通信获得相关服务信息并进行DNS注册，使用内存树状保存dns配置
        image: gcr.io/google_containers/k8s-dns-kube-dns-amd64:1.14.4
        resources:
          # TODO: Set memory limits when we've profiled the container for large
          # clusters, then set request = limit to keep this container in
          # guaranteed class. Currently, this container falls into the
          # "burstable" category so the kubelet doesn't backoff from restarting it.
          limits:
            memory: 170Mi
          requests:
            cpu: 100m
            memory: 70Mi
        ##livnessprboe负责探测相关容器是否存活（running），如果超过5次探测失败就要kill掉，重启该容器
        livenessProbe:
          httpGet:
            path: /healthcheck/kubedns
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        ##readiness 用于检测容器服务是否已经就绪（ready状态），如果不就绪，service里就会删除该pod
        readinessProbe:
          httpGet:
            path: /readiness
            port: 8081
            scheme: HTTP
          # we poll on pod startup for the Kubernetes master service and
          # only setup the /readiness HTTP server once that's available.
          initialDelaySeconds: 3
          timeoutSeconds: 5
        ##容器启动参数
        args:
        - --domain=cluster.local.
        - --dns-port=10053
        - --config-dir=/kube-dns-config
        - --v=2
        #{{ pillar['federations_domain_map'] }}
        - --kube-master-url=http://172.16.199.17:8080
        #容器环境变量
        env:
        - name: PROMETHEUS_PORT
          value: "10055"
        ports:
        - containerPort: 10053
          name: dns-local
          protocol: UDP
        - containerPort: 10053
          name: dns-tcp-local
          protocol: TCP
        - containerPort: 10055
          name: metrics
          protocol: TCP
        #具体容器volume挂载，这里的name必须等于spec.template.spec.volume下的名称定义
        volumeMounts:
        - name: kube-dns-config
          mountPath: /kube-dns-config
      - name: dnsmasq
      ##dnsmasq提供缓存，并对其它pod提供DNS查询接口，该容器实际上是service里定义的真实dns通信端口
        image: gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.4
        livenessProbe:
          httpGet:
            path: /healthcheck/dnsmasq
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - -v=2
        - -logtostderr
        - -configDir=/etc/k8s/dns/dnsmasq-nanny
        - -restartDnsmasq=true
        - --
        - -k
        ##dnsmasq缓存大小
        - --cache-size=1000
        - --log-facility=-
        ##指定dnsmasq的上级查询服务器
        - --server=/cluster.local./127.0.0.1#10053
        - --server=/in-addr.arpa/127.0.0.1#10053
        - --server=/ip6.arpa/127.0.0.1#10053
        ports:
        - containerPort: 53
          name: dns
          protocol: UDP
        - containerPort: 53
          name: dns-tcp
          protocol: TCP
        # see: https://github.com/kubernetes/kubernetes/issues/29055 for details
        resources:
          requests:
            cpu: 150m
            memory: 20Mi
        volumeMounts:
        - name: kube-dns-config
          mountPath: /etc/k8s/dns/dnsmasq-nanny
      - name: sidecar
      ##sidecar负责对上述两个容器服务进行健康性探测，执行具体的dnsprobe请求来确认dns服务是否正常
      ##对外暴露了10054端口，可通过curl http://pod-ip/metrics获得输出
        image: gcr.io/google_containers/k8s-dns-sidecar-amd64:1.14.4
        livenessProbe:
          httpGet:
            path: /metrics
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --v=2
        - --logtostderr
        - --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local.,5,A
        - --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local.,5,A
        ports:
        - containerPort: 10054
          name: metrics
          protocol: TCP
        resources:
          requests:
            memory: 20Mi
            cpu: 10m
      dnsPolicy: Default  # Don't use cluster DNS. 使得pod使用kubelet设置的DNS
      serviceAccountName: kube-dns

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[root@docker1 kubedns]# cat kubedns-controller.yaml

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

# http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# Should keep target in cluster/addons/dns-horizontal-autoscaler/dns-horizontal-autoscaler.yaml

# in sync with this file.

# Warning: This is a file generated from the base underscore template file: kubedns-controller.yaml.base

apiVersion: extensions/v1beta1

kind: Deployment

metadata:

namespace: kube-system

#deployment自定义标签

labels:

k8s-app: kube-dns

kubernetes.io/cluster-service: "true"

addonmanager.kubernetes.io/mode: Reconcile

#Spec--pod详细定义

spec:

# replicas: not specified here:

# 1. In order to make Addon Manager do not reconcile this replicas parameter.

# 2. Default is 1.

# 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on.

strategy:

rollingUpdate:

maxSurge: 10%

maxUnavailable: 0

selector:

matchLabels:

k8s-app: kube-dns

template:

metadata:

labels:

k8s-app: kube-dns

#自定义注解，调度中的关键pod

annotations:

scheduler.alpha.kubernetes.io/critical-pod: ''

spec:

tolerations:

- key: "CriticalAddonsOnly"

operator: "Exists"

#pod的volume定义，提供给pod内所有container mount

volumes:

- name: kube-dns-config

#使用config map配置，cm可以通过kubectl get cm -n kube-system获得

###################################################

#[root@docker1 ~]# kubectl get cm -n kube-system -o yaml

#apiVersion: v1

#items:

#- apiVersion: v1

# kind: ConfigMap

# metadata:

# creationTimestamp: 2017-07-09T15:07:48Z

# labels:

# addonmanager.kubernetes.io/mode: EnsureExists

# name: kube-dns

# namespace: kube-system

# resourceVersion: "5693"

# selfLink: /api/v1/namespaces/kube-system/configmaps/kube-dns

# uid: 5ebf1bf0-64b8-11e7-ae06-000c29420d98

#kind: List

#resourceVersion: ""

#selfLink: ""

##################################################

configMap:

optional: true

####开始具体容器的定义####

containers:

- name: kubedns

###kubedns容器负责和k8s API接口通信获得相关服务信息并进行DNS注册，使用内存树状保存dns配置

image: gcr.io/google_containers/k8s-dns-kube-dns-amd64:1.14.4

resources:

# TODO: Set memory limits when we've profiled the container for large

# clusters, then set request = limit to keep this container in

# guaranteed class. Currently, this container falls into the

# "burstable" category so the kubelet doesn't backoff from restarting it.

limits:

memory: 170Mi

requests:

cpu: 100m

memory: 70Mi

##livnessprboe负责探测相关容器是否存活（running），如果超过5次探测失败就要kill掉，重启该容器

livenessProbe:

httpGet:

path: /healthcheck/kubedns

port: 10054

scheme: HTTP

initialDelaySeconds: 60

timeoutSeconds: 5

successThreshold: 1

failureThreshold: 5

##readiness 用于检测容器服务是否已经就绪（ready状态），如果不就绪，service里就会删除该pod

readinessProbe:

httpGet:

path: /readiness

port: 8081

scheme: HTTP

# we poll on pod startup for the Kubernetes master service and

# only setup the /readiness HTTP server once that's available.

initialDelaySeconds: 3

timeoutSeconds: 5

##容器启动参数

args:

- --domain=cluster.local.

- --dns-port=10053

- --config-dir=/kube-dns-config

- --v=2

#{{ pillar['federations_domain_map'] }}

- --kube-master-url=http://172.16.199.17:8080

#容器环境变量

env:

- name: PROMETHEUS_PORT

value: "10055"

ports:

- containerPort: 10053

protocol: UDP

- containerPort: 10053

protocol: TCP

- containerPort: 10055

protocol: TCP

#具体容器volume挂载，这里的name必须等于spec.template.spec.volume下的名称定义

volumeMounts:

- name: kube-dns-config

mountPath: /kube-dns-config

- name: dnsmasq

##dnsmasq提供缓存，并对其它pod提供DNS查询接口，该容器实际上是service里定义的真实dns通信端口

image: gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.4

livenessProbe:

httpGet:

path: /healthcheck/dnsmasq

port: 10054

scheme: HTTP

initialDelaySeconds: 60

timeoutSeconds: 5

successThreshold: 1

failureThreshold: 5

args:

- -v=2

- -logtostderr

- -configDir=/etc/k8s/dns/dnsmasq-nanny

- -restartDnsmasq=true

- --

- -k

##dnsmasq缓存大小

- --cache-size=1000

- --log-facility=-

##指定dnsmasq的上级查询服务器

- --server=/cluster.local./127.0.0.1#10053

- --server=/in-addr.arpa/127.0.0.1#10053

- --server=/ip6.arpa/127.0.0.1#10053

ports:

- containerPort: 53

protocol: UDP

- containerPort: 53

protocol: TCP

# see: https://github.com/kubernetes/kubernetes/issues/29055 for details

resources:

requests:

cpu: 150m

memory: 20Mi

volumeMounts:

- name: kube-dns-config

mountPath: /etc/k8s/dns/dnsmasq-nanny

- name: sidecar

##sidecar负责对上述两个容器服务进行健康性探测，执行具体的dnsprobe请求来确认dns服务是否正常

##对外暴露了10054端口，可通过curl http://pod-ip/metrics获得输出

image: gcr.io/google_containers/k8s-dns-sidecar-amd64:1.14.4

livenessProbe:

httpGet:

path: /metrics

port: 10054

scheme: HTTP

initialDelaySeconds: 60

timeoutSeconds: 5

successThreshold: 1

failureThreshold: 5

args:

- --v=2

- --logtostderr

- --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local.,5,A

- --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local.,5,A

ports:

- containerPort: 10054

protocol: TCP

resources:

requests:

memory: 20Mi

cpu: 10m

dnsPolicy: Default # Don't use cluster DNS. 使得pod使用kubelet设置的DNS

serviceAccountName: kube-dns

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kube-dns deployment文件分析

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