Kubernetes（k8s）的RC(Replication Controller)副本控制器
薛正华 2020-06-21
1、RC(Replication Controller)副本控制器，Replication Controller的作用。
应用托管在kubernetes之后，kubernetes需要保证应用能够持续运行，这是RC的工作内容，它会确保任何时间kubernetes中都有指定数量的Pod在运行。在此基础上，RC还提供了一些更高级的特性，比如滚动升级，升级回滚等等。
通俗的理解就是，当将应用通过K8s运行起来之后，我们的k8s是需要保证容器一直处于持续运行，保证它的高可用，那么我们的RC就可以确保容器的高可用，RC的工作原理就是，RC是会一直监控我们的K8S容器，也就是说POD资源它的运行状态，一旦发现这个Pod资源有异常了，那么我们的RC就会控制k8s在其他的Node节点上启动一个新的Pod，以此来保证这个业务的高可用运行。RC除了保证Pod高可用之外，还提供了更高级的特性，比如滚动升级，升级回滚等等。
2、首先，查看你的k8s各个节点状态是否正常运行，然后创建一个rc的目录，用于存放RC(Replication Controller)的yaml配置文件。
[ ~]# kubectl get nods
the server doesn‘t have a resource type "nods"
[ ~]# kubectl get node
NAME STATUS AGE
k8s-master Ready 6d
k8s-node2 Ready 6d
k8s-node3 Ready 6d
[ ~]# kubectl get nodes
NAME STATUS AGE
k8s-master Ready 6d
k8s-node2 Ready 6d
k8s-node3 Ready 6d
[ ~]# clear
[ ~]# kubectl get componentstatus
NAME STATUS MESSAGE ERROR
scheduler Healthy ok
controller-manager Healthy ok
etcd-0 Healthy {"health":"true"}
[ ~]# clear
[ ~]# cd k8s/
[master k8s]# ls
pod
[master k8s]# mkdir rc
[ k8s]# cd rc/
[master rc]# ls
[master rc]# vim nginx_rc_yaml
[ rc]# kubectl create -f nginx_rc_yaml
replicationcontroller "myweb" created
[ rc]# kubectl get rc
NAME DESIRED CURRENT READY AGE
myweb 2 2 1 13s
[ rc]#创建nginx_rc_yaml配置文件，配置内容，如下所示。
# 声明api的版本。
apiVersion: v1
# kind代表资源的类型，资源是ReplicationController。
kind: ReplicationController
# 资源叫什么名字，是在其属性metadata里面的。
metadata:
# 第一个属性name的值是myweb，即ReplicationController的名字就叫做myweb。
name: myweb
# spec是详细，详细里面定义了一个容器。
spec:
# 声明副本数量是2，代表了RC会启动两个相同的Pod。
replicas: 2
# 选择器。
selector:
app: myweb
# Pod的启动模板，和Pod的yaml配置信息基本差不多的，几乎一样，但是这里没有名称，是因为两个Pod名称不能完全一样的。
# 没有指定名称，RC会随机生成一个名称。
template:
# 资源叫什么名字，是在其属性metadata里面的。但是这里让RC随机生成指定数量的名称。
metadata:
# 给Pod贴上了一个标签，标签是app: web，标签是有一定的作用的。
labels:
app: myweb
# spec是详细，详细里面定义了一个容器。
spec:
# 定义一个容器，可以声明多个容器的。
containers:
# 容器的名称叫做myweb
- name: myweb
# 使用了什么镜像，可以使用官方公有的，也可以使用私有的。
image: 192.168.110.133:5000/nginx:1.13
# ports定义容器的端口。
ports:
# 容器的端口是80，如果容器有多个端口，可以在后面接着写一行即可。
- containerPort: 80配置，如下所示：
如果如何控制yaml的格式，可以使用notepad++的yaml语言格式，或者在线yaml解析，或者idea的yaml配置文件，idea的yaml配置文件也推荐使用哦。
创建好RC(Replication Controller)之后，可以进行检查。可以看到RC创建了两个Pod，可以查看一下Pod的数量和状态。
[ rc]# kubectl get rc NAME DESIRED CURRENT READY AGE myweb 2 2 1 7m [ rc]# kubectl get pods NAME READY STATUS RESTARTS AGE myweb-0hqc5 0/1 ImagePullBackOff 0 8m myweb-2np4k 1/1 Running 0 8m nginx 1/1 Running 1 3d test1 0/1 ImagePullBackOff 0 2d test2 2/2 Running 1 2d test4 1/1 Running 0 2d [ rc]#
很明显，我这里创建的两个Pod，有一个启动失败了。此时，我想将失败的Pod删除掉，但是我删除了一个，RC又帮助你启动了一个，嗯，真的是高可用啊，然后我将RC删除掉，这两个Pod就随着被删除掉了。
[ ~]# kubectl get rc NAME DESIRED CURRENT READY AGE myweb 2 2 1 17m [ ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE myweb-8cp7h 0/1 ImagePullBackOff 0 5m 172.16.85.3 k8s-master myweb-qcgjl 1/1 Running 1 14m 172.16.5.2 k8s-node2 nginx 1/1 Running 2 3d 172.16.38.3 k8s-node3 test1 0/1 ImagePullBackOff 0 2d 172.16.85.2 k8s-master test2 2/2 Running 3 2d 172.16.38.2 k8s-node3 test4 1/1 Running 1 2d 172.16.5.3 k8s-node2 [ ~]# kubectl delete rc myweb replicationcontroller "myweb" deleted [ ~]# kubectl get rc No resources found. [ ~]#
这里我将没有用的测试Pod都删除掉，因为我笔记本只有8g内存，可能内存不够用了。搞了一个小时，不是内存的问题，是之前部署k8s的时候，测试nginx的时候将nginx拼错了，尴尬。
[ ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB 192.168.110.133:5000/nginx 1.13 ae513a47849c 2 years ago 109 MB docker.io/nginx 1.13 ae513a47849c 2 years ago 109 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB docker.io/tianyebj/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ ~]#
而我的RC的yaml的配置文件，如下所示：
Version: v1
kind: ReplicationController
metadata:
name: myweb
spec:
replicas: 2
selector:
app: myweb
template:
metadata:
labels:
app: myweb
spec:
containers:
- name: myweb
image: 192.168.110.133:5000/nginx:1.13
# imagePullPolicy: IfNotPresent
ports:
- containerPort: 80但是主节点的docker镜像是192.168.110.133:5000/ngnix，造成了每次创建RC，在主节点的Pod都无法启动，尴尬，还排查了这么久。真打脸。
[ ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB 192.168.110.133:5000/ngnix 1.13 ae513a47849c 2 years ago 109 MB registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ ~]#
报错信息，也贴一下吧，方便自己以后使用，如下所示：
[ ~]# kubectl describe pod myweb-qwgsf
Name: myweb-qwgsf
Namespace: default
Node: k8s-master/192.168.110.133
Start Time: Thu, 11 Jun 2020 17:21:45 +0800
Labels: app=myweb
Status: Pending
IP: 172.16.85.2
Controllers: ReplicationController/myweb
Containers:
myweb:
Container ID:
Image: 192.168.110.133:5000/nginx:1.13
Image ID:
Port: 80/TCP
State: Waiting
Reason: ErrImagePull
Ready: False
Restart Count: 0
Volume Mounts: <none>
Environment Variables: <none>
Conditions:
Type Status
Initialized True
Ready False
PodScheduled True
No volumes.
QoS Class: BestEffort
Tolerations: <none>
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
12m 12m 1 {kubelet k8s-master} Warning MissingClusterDNS kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
12m 12m 1 {default-scheduler } Normal Scheduled Successfully assigned myweb-qwgsf to k8s-master
12m 6m 6 {kubelet k8s-master} spec.containers{myweb} Normal Pulling pulling image "192.168.110.133:5000/nginx:1.13"
12m 6m 6 {kubelet k8s-master} spec.containers{myweb} Warning Failed Failed to pull image "192.168.110.133:5000/nginx:1.13": Error while pulling image: Get http://192.168.110.133:5000/v1/repositories/nginx/images: dial tcp 192.168.110.133:5000: connect: connection refused
12m 6m 6 {kubelet k8s-master} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "myweb" with ErrImagePull: "Error while pulling image: Get http://192.168.110.133:5000/v1/repositories/nginx/images: dial tcp 192.168.110.133:5000: connect: connection refused"
12m 4m 31 {kubelet k8s-master} spec.containers{myweb} Normal BackOff Back-off pulling image "192.168.110.133:5000/nginx:1.13"
12m 4m 31 {kubelet k8s-master} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "myweb" with ImagePullBackOff: "Back-off pulling image \"192.168.110.133:5000/nginx:1.13\""
32s 32s 1 {kubelet k8s-master} Warning MissingClusterDNS kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.
31s 20s 2 {kubelet k8s-master} spec.containers{myweb} Normal Pulling pulling image "192.168.110.133:5000/nginx:1.13"
31s 20s 2 {kubelet k8s-master} spec.containers{myweb} Warning Failed Failed to pull image "192.168.110.133:5000/nginx:1.13": Error while pulling image: Get http://192.168.110.133:5000/v1/repositories/nginx/images: dial tcp 192.168.110.133:5000: connect: connection refused
31s 20s 2 {kubelet k8s-master} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "myweb" with ErrImagePull: "Error while pulling image: Get http://192.168.110.133:5000/v1/repositories/nginx/images: dial tcp 192.168.110.133:5000: connect: connection refused"
30s 8s 2 {kubelet k8s-master} spec.containers{myweb} Normal BackOff Back-off pulling image "192.168.110.133:5000/nginx:1.13"
30s 8s 2 {kubelet k8s-master} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "myweb" with ImagePullBackOff: "Back-off pulling image \"192.168.110.133:5000/nginx:1.13\""此处，将主节点的Docker镜像删除掉。
[ ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB 192.168.110.133:5000/ngnix 1.13 ae513a47849c 2 years ago 109 MB registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES [ ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a27987d97039 registry "/entrypoint.sh /e..." 5 days ago Exited (2) 3 days ago registry ee95778bd5d9 busybox "sh" 6 days ago Exited (127) 6 days ago friendly_payne 6d459781a3e5 busybox "sh" 6 days ago Exited (137) 5 days ago gracious_nightingale [ ~]# docker rmi -f ae513a47849c Untagged: 192.168.110.133:5000/ngnix:1.13 Untagged: 192.168.110.133:5000/:e4f0474a75c510f40b37b6b7dc2516241ffa8bde5a442bde3d372c9519c84d90 Deleted: sha256:ae513a47849c895a155ddfb868d6ba247f60240ec8495482eca74c4a2c13a881 Deleted: sha256:160a8bd939a9421818f499ba4fbfaca3dd5c86ad7a6b97b6889149fd39bd91dd Deleted: sha256:f246685cc80c2faa655ba1ec9f0a35d44e52b6f83863dc16f46c5bca149bfefc Deleted: sha256:d626a8ad97a1f9c1f2c4db3814751ada64f60aed927764a3f994fcd88363b659 [ ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ ~]#
此时，将三台节点重启了，或者重启服务，我这里直接重启了三台机器，其所有服务全部重启。
[ ~]# free -h
total used free shared buff/cache available
Mem: 2.2G 880M 453M 12M 953M 1.1G
Swap: 2.0G 0B 2.0G
[ ~]# kubectl get node
NAME STATUS AGE
k8s-master Ready 6d
k8s-node2 Ready 6d
k8s-node3 Ready 6d
[ ~]# kubectl get componentstatus
NAME STATUS MESSAGE ERROR
scheduler Healthy ok
controller-manager Healthy ok
etcd-0 Healthy {"health":"true"}
[ ~]# kubectl get rc
NAME DESIRED CURRENT READY AGE
myweb 2 2 2 16m
[ ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/nginx latest 2622e6cca7eb 41 hours ago 132 MB
docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB
docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB
192.168.110.133:5000/nginx 1.13 ae513a47849c 2 years ago 109 MB
docker.io/nginx 1.13 ae513a47849c 2 years ago 109 MB
registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB
192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB
[ ~]# kubectl get node -o wide
NAME STATUS AGE EXTERNAL-IP
k8s-master Ready 6d <none>
k8s-node2 Ready 6d <none>
k8s-node3 Ready 6d <none>
[ ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE
myweb-2h8b1 1/1 Running 1 17m 172.16.85.2 k8s-master
myweb-lfkmp 1/1 Running 1 17m 172.16.5.2 k8s-node2
test4 1/1 Running 1 13m 172.16.38.2 k8s-node3
[ ~]#
RC(Replication Controller)会始终保持Pod的数量为2，可以自己删除一个Pod，k8s的RC(Replication Controller)会里面帮助你启动一个新的Pod，RC(Replication Controller)会时刻监控Pod的状态，少了就启动，多了就进行删除，数量和配置文件yaml的数量一致。
3、RC(Replication Controller)如何与Pod进行关联呢？
答：使用到的标签Label（标签选择器）。在nginx_rc.yaml配置文件中，定义了RC的选择器是通过标签app:myweb来选择的，每一个Pod在运行的时候会自动加上一个标签叫做app:myweb，这样的话，RC会自动根据标签来选择我们的Pod。
可以通过命令kubectl describe pod myweb-2h8b1来查看标签。
[ rc]# kubectl describe pod myweb-2h8b1
Name: myweb-2h8b1
Namespace: default
Node: k8s-master/192.168.110.133
Start Time: Thu, 11 Jun 2020 17:51:06 +0800
Labels: app=myweb
Status: Running
IP: 172.16.85.2
Controllers: ReplicationController/myweb
Containers:
myweb:
Container ID: docker://27a9e6dfb65be540bb50c98d820a5b773c0ed01d09d2350baf6027cdf9e22257
Image: 192.168.110.133:5000/nginx:1.13
Image ID: docker-pullable://docker.io/:b1d09e9718890e6ebbbd2bc319ef1611559e30ce1b6f56b2e3b479d9da51dc35
Port: 80/TCP
State: Running
Started: Thu, 11 Jun 2020 18:06:34 +0800
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Thu, 11 Jun 2020 18:01:41 +0800
Finished: Thu, 11 Jun 2020 18:05:42 +0800
Ready: True
Restart Count: 1
Volume Mounts: <none>
Environment Variables: <none>
Conditions:
Type Status
Initialized True
Ready True
PodScheduled True
No volumes.
QoS Class: BestEffort
Tolerations: <none>
No events.
[ rc]#
通过查看RC的标签。
[ rc]# kubectl get rc -o wide NAME DESIRED CURRENT READY AGE CONTAINER(S) IMAGE(S) SELECTOR myweb 2 2 2 3h myweb 192.168.110.133:5000/nginx:1.13 app=myweb [ rc]#
RC(Replication Controller)是通过标签（标签选择器）来选择Pod，通过标签来决定这个Pod是归我来管理的。
通过修改创建好的Pod可以测试，如果多于指定数量的Pod数量，就会被删除掉，注意，删除掉的Pod是最年轻的那个Pod。kubectl edit pod test4命令可以修改创建好的Pod。
[ rc]# kubectl get all NAME DESIRED CURRENT READY AGE rc/myweb 2 2 2 3h NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE svc/kubernetes 10.254.0.1 <none> 443/TCP 6d NAME READY STATUS RESTARTS AGE po/myweb-2h8b1 1/1 Running 1 3h po/myweb-lfkmp 1/1 Running 1 3h po/test4 1/1 Running 1 3h [master rc]# kubectl edit pod test4 pod "test4" edited [ rc]# kubectl get all NAME DESIRED CURRENT READY AGE rc/myweb 2 2 2 3h NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE svc/kubernetes 10.254.0.1 <none> 443/TCP 6d NAME READY STATUS RESTARTS AGE po/myweb-lfkmp 1/1 Running 1 3h po/test4 1/1 Running 1 3h [ rc]#
4、RC(Replication Controller)的滚动升级。
答：滚动升级是一种平滑过渡的升级方式，通过逐步替换的策略，保证整体系统的稳定，在初始升级的时候就可以及时发现，调整问题，以保证问题影响度不好扩大。Kubernetes中滚动升级的命令如下所示：
首先，这里将配置文件nginx_rc.yaml进行拷贝，然后修改配置文件nginx_rc2.yaml，将myweb替换为myweb2。
[master rc]# cp nginx_rc.yaml nginx_rc2.yaml [master rc]# ls nginx_rc2.yaml nginx_rc.yaml [master rc]# vim nginx_rc2.yaml [ rc]#
具体配置，如下所示：
将myweb替换为myweb2，替换过后，然后将镜像版本修改为latest版本，如下所示：
将Nginx的latest版本镜像拉取下来docker pull docker.io/nginx:latest。然后将镜像上传到私有仓库里面，方便下载。
这里需要注意的是，我之前在配置Docker镜像加速的时候，在三台机器的vim /etc/sysconfig/docker。
1 [ ~]# vim /etc/sysconfig/docker
我在这个配置文件里面加的镜像加速和配置私有仓库地址。貌似并不是很好使的。
下面，在三台机器的上面，进行如下配置，将Docker镜像加速和私有仓库配置到下面这里。
1 [ ~]# docker pull docker.io/nginx:1.15 2 Trying to pull repository docker.io/library/nginx ... 3 Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
修改配置文件，在三台机器上面都配置如下所示配置，[ ~]# vim /etc/docker/daemon.json
1 { "insecure-registries":["192.168.110.133:5000"] ,"registry-mirrors":["https://docker.mirrors.ustc.edu.cn"]}然后重启三台机器的Docker服务systemctl restart docker。如果实在下载不下来，需要自己从网上找个https://hub.docker.com/
[ ~]# docker pull docker.io/nginx:1.15 Trying to pull repository docker.io/library/nginx ... sha256:23b4dcdf0d34d4a129755fc6f52e1c6e23bb34ea011b315d87e193033bcd1b68: Pulling from docker.io/library/nginx 743f2d6c1f65: Pull complete 6bfc4ec4420a: Pull complete 688a776db95f: Pull complete Digest: sha256:23b4dcdf0d34d4a129755fc6f52e1c6e23bb34ea011b315d87e193033bcd1b68 Status: Downloaded newer image for docker.io/nginx:1.15 [ ~]#
然后将ngnix1.15上传到私有仓库里面。可以使用docker images命令查看是否已经上传到私有仓库。
[master rc]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB docker.io/nginx 1.15 53f3fd8007f7 13 months ago 109 MB 192.168.110.133:5000/nginx 1.13 ae513a47849c 2 years ago 109 MB docker.io/nginx 1.13 ae513a47849c 2 years ago 109 MB registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ rc]# docker tag docker.io/nginx:1.15 192.168.110.133:5000/nginx:1.15 [ rc]# docker push 192.168.110.133:5000/nginx:1.15 The push refers to a repository [192.168.110.133:5000/nginx] Put http://192.168.110.133:5000/v1/repositories/nginx/: dial tcp 192.168.110.133:5000: connect: connection refused [master rc]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 8 days ago 1.22 MB docker.io/registry latest 708bc6af7e5e 4 months ago 25.8 MB docker.io/nginx 1.15 53f3fd8007f7 13 months ago 109 MB 192.168.110.133:5000/nginx 1.15 53f3fd8007f7 13 months ago 109 MB docker.io/nginx 1.13 ae513a47849c 2 years ago 109 MB 192.168.110.133:5000/nginx 1.13 ae513a47849c 2 years ago 109 MB registry.access.redhat.com/rhel7/pod-infrastructure latest 99965fb98423 2 years ago 209 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ rc]#
滚动升级是一种平滑过渡的升级方式，通过逐步替换的策略，保证整体系统的稳定，在初始升级的时候就可以及时发现，调整问题，以保证问题影响度不好扩大。Kubernetes中滚动升级的命令如下所示：
这里需要注意的是，想要看看Docker私有仓库是否有你想要的镜像，可以使用如下所示查看：
[node3 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/busybox latest 1c35c4412082 9 days ago 1.22 MB 192.168.110.133:5000/nginx 1.15 53f3fd8007f7 13 months ago 109 MB docker.io/nginx 1.15 53f3fd8007f7 13 months ago 109 MB 192.168.110.133:5000/nginx 1.13 ae513a47849c 2 years ago 109 MB docker.io/tianyebj/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB 192.168.110.133:5000/pod-infrastructure latest 34d3450d733b 3 years ago 205 MB [ docker]#
还有关于使用镜像加速和私有仓库的配置，这里需要说明的是，我的Docker的版本是1.13.1。
[ ~]# docker version Client: Version: 1.13.1 API version: 1.26 Package version: docker-1.13.1-161.git64e9980.el7_8.x86_64 Go version: go1.10.3 Git commit: 64e9980/1.13.1 Built: Tue Apr 28 14:43:01 2020 OS/Arch: linux/amd64 Server: Version: 1.13.1 API version: 1.26 (minimum version 1.12) Package version: docker-1.13.1-161.git64e9980.el7_8.x86_64 Go version: go1.10.3 Git commit: 64e9980/1.13.1 Built: Tue Apr 28 14:43:01 2020 OS/Arch: linux/amd64 Experimental: false [ ~]#
关于镜像加速和私有仓库的配置，我此时由于不需要从网上下载所需的软件，这里将三台机器的/etc/docker/daemon.json配置文件全部后面加上了_bak，这里不需要使用它们了。
[ ~]# cat /etc/docker/daemon.json_bak
{ "insecure-registries":["192.168.110.133:5000"]}
[ ~]# cd /etc/docker/
[node3 docker]# ls
certs.d daemon.json_20200612 daemon.json_bak key.json seccomp.json
[ docker]#
关于镜像加速和私有仓库的配置，如果配置不好，真的难为si你的。所以这里说了很多次。此时，三台机器的镜像加速和私有中心在这个里面还进行了配置。特此说明。
[ docker]# cat /etc/sysconfig/docker
# /etc/sysconfig/docker
# Modify these options if you want to change the way the docker daemon runs
# OPTIONS=‘--selinux-enabled --log-driver=journald --signature-verification=false‘
# 信任私有仓库，镜像加速
OPTIONS=‘--selinux-enabled --log-driver=journald --signature-verification=false
--registry-mirror=https://registry.docker-cn.com --insecure-registry=192.168.110.133:5000‘
if [ -z "${DOCKER_CERT_PATH}" ]; then
DOCKER_CERT_PATH=/etc/docker
fi
# Do not add registries in this file anymore. Use /etc/containers/registries.conf
# instead. For more information reference the registries.conf(5) man page.
# Location used for temporary files, such as those created by
# docker load and build operations. Default is /var/lib/docker/tmp
# Can be overriden by setting the following environment variable.
# DOCKER_TMPDIR=/var/tmp
# Controls the /etc/cron.daily/docker-logrotate cron job status.
# To disable, uncomment the line below.
# LOGROTATE=false
# docker-latest daemon can be used by starting the docker-latest unitfile.
# To use docker-latest client, uncomment below lines
#DOCKERBINARY=/usr/bin/docker-latest
#DOCKERDBINARY=/usr/bin/dockerd-latest
#DOCKER_CONTAINERD_BINARY=/usr/bin/docker-containerd-latest
#DOCKER_CONTAINERD_SHIM_BINARY=/usr/bin/docker-containerd-shim-latest
[ docker]#
饶了一大圈，此时进行滚动升级，滚动升级是一种平滑过渡的升级方式，通过逐步替换的策略，保证整体系统的稳定，在初始升级的时候就可以及时发现，调整问题，以保证问题影响度不好扩大。Kubernetes中滚动升级的命令如下所示：
[ rc]# kubectl rolling-update myweb -f nginx_rc2.yaml --update-period=10s Created myweb2 Scaling up myweb2 from 0 to 2, scaling down myweb from 2 to 0 (keep 2 pods available, don‘t exceed 3 pods) Scaling myweb2 up to 1 Scaling myweb down to 1 Scaling myweb2 up to 2 Scaling myweb down to 0 Update succeeded. Deleting myweb replicationcontroller "myweb" rolling updated to "myweb2" [ rc]#
创建一个myweb2的RC，将myweb2的RC的Pod数量由0调整为2，把myweb的RC的Pod数量由2调整为0。当myweb2存活了30秒以上就会删掉一个myweb，nginx也是myweb的容器，删除也是比较慢的。
升级开始后，首先依据提供的定义文件创建V2版本的RC，然后每隔10s（--update-period=10s）逐步的增加V2版本的Pod副本数，逐步减少V1版本Pod的副本数。升级完成之后，删除V1版本的RC，保留V2版本的RC，以及实现滚动升级。
[ ~]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE myweb2-f5400 1/1 Running 0 15s 172.16.38.3 k8s-node3 myweb2-mg9sk 1/1 Running 0 26s 172.16.85.2 k8s-master [ ~]#
升级之后还可以进行回滚，如下所示：
[ rc]# kubectl rolling-update myweb2 -f nginx_rc.yaml --update-period=10s Created myweb Scaling up myweb from 0 to 2, scaling down myweb2 from 2 to 0 (keep 2 pods available, don‘t exceed 3 pods) Scaling myweb up to 1 Scaling myweb2 down to 1 Scaling myweb up to 2 Scaling myweb2 down to 0 Update succeeded. Deleting myweb2 replicationcontroller "myweb2" rolling updated to "myweb" [ rc]#
升级过程中，发生了错误中途退出时候，可以选择继续升级。Kubernetes能够智能的判断升级中断之前的状态，然后紧接着继续执行升级。当然，也可以进行退出，命令如下所示：
[ rc]# kubectl rolling-update myweb myweb2 --update-period=10s --rollback Setting "myweb" replicas to 2 Continuing update with existing controller myweb. Scaling up myweb from 2 to 2, scaling down myweb2 from 1 to 0 (keep 2 pods available, don‘t exceed 3 pods) Scaling myweb2 down to 0 Update succeeded. Deleting myweb2 replicationcontroller "myweb" rolling updated to "myweb2" [ rc]#
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