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更新cilium文档、滚动更新文档
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gjmzj committed Aug 19, 2018
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6 changes: 3 additions & 3 deletions docs/06.cilium.md
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![cilium_http_gsg](../pics/cilium_http_gsg.jpg)

根据文件[http-sw-app.yaml](..//roles/cilium/files/star_war_example/http-sw-app.yaml) 创建 `$ kubectl create -f http-sw-app.yaml` 后，验证如下：
根据文件[http-sw-app.yaml](../roles/cilium/files/star_war_example/http-sw-app.yaml) 创建 `$ kubectl create -f http-sw-app.yaml` 后，验证如下：

``` bash
$ kubectl get pods,svc
Expand Down Expand Up @@ -88,7 +88,7 @@ Ship landed # 成功着陆

![cilium_http_l3_l4_gsg](../pics/cilium_http_l3_l4_gsg.jpg)

根据文件[sw_l3_l4_policy.yaml](..//roles/cilium/files/star_war_example/sw_l3_l4_policy.yaml) 创建 `$ kubectl apply -f sw_l3_l4_policy.yaml` 后，验证如下：
根据文件[sw_l3_l4_policy.yaml](../roles/cilium/files/star_war_example/sw_l3_l4_policy.yaml) 创建 `$ kubectl apply -f sw_l3_l4_policy.yaml` 后，验证如下：

``` bash
$ kubectl exec tiefighter -- curl -s -XPOST deathstar.default.svc.cluster.local/v1/request-landing
Expand Down Expand Up @@ -148,7 +148,7 @@ main.main()

![cilium_http_l3_l4_l7_gsg](../pics/cilium_http_l3_l4_l7_gsg.jpg)

限制L7 的安全策略，根据文件[sw_l3_l4_l7_policy.yaml](..//roles/cilium/files/star_war_example/sw_l3_l4_l7_policy.yaml) 创建 `$ kubectl apply -f sw_l3_l4_policy.yaml` 后，验证如下：
限制L7 的安全策略，根据文件[sw_l3_l4_l7_policy.yaml](../roles/cilium/files/star_war_example/sw_l3_l4_l7_policy.yaml) 创建 `$ kubectl apply -f sw_l3_l4_l7_policy.yaml` 后，验证如下：

``` bash
$ kubectl exec tiefighter -- curl -s -XPOST deathstar.default.svc.cluster.local/v1/request-landing
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221 changes: 169 additions & 52 deletions docs/guide/rollingupdateWithZeroDowntime.md
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## 4、演示
>使用kubectl更新一个已部署的应用程序，并模拟回滚。为了方便分析，将应用程序的pod副本数量设置为10。
```javascript
kubectl -n k8s-ecoysystem-apps scale deployment helloworldapi --replicas=10
``` bash
$ kubectl run busy --image=busybox:1.28.4 sleep 36000000 --replicas=10
```
### 4.1. 发布微服务
```javascript
查看部署列表
$ kubectl get deployments -n k8s-ecoysystem-apps
查看正在运行的pod
$ kubectl get pods -n k8s-ecoysystem-apps
通过pod描述，查看应用程序的当前映像版本
$ kubectl describe pods -n k8s-ecoysystem-apps
- 当前服务状态查看
``` bash
# 查看部署列表
root@kube-aio:~# kubectl get deploy busy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
busy 10 10 10 10 5m

# 查看正在运行的pod
root@kube-aio:~# kubectl get pod | grep busy
busy-794c95f5d7-56b6w 1/1 Running 0 5m
busy-794c95f5d7-8ddjr 1/1 Running 0 5m
busy-794c95f5d7-8zm8r 1/1 Running 0 5m
busy-794c95f5d7-9hjhp 1/1 Running 0 5m
busy-794c95f5d7-df2r2 1/1 Running 0 5m
busy-794c95f5d7-fsn94 1/1 Running 0 5m
busy-794c95f5d7-k4w8r 1/1 Running 0 5m
busy-794c95f5d7-lsmgb 1/1 Running 0 5m
busy-794c95f5d7-rg8kw 1/1 Running 0 5m
busy-794c95f5d7-xpxxt 1/1 Running 0 5m

# 通过pod描述，查看应用程序的当前映像版本
root@kube-aio:~# kubectl describe pod busy-794c95f5d7-56b6w |grep Image
Image: busybox:1.28.4
Image ID: docker-pullable://busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47
```
![](../../pics/prePublish.png)

```javascript
升级镜像版本到v2.3
$ kubectl -n k8s-ecoysystem-apps set image deployments/helloworldapi helloworldapi=registry.wuling.com/justmine/helloworldapi:v2.3
- 升级镜像版本到1.29
- 为了更清晰看到更新过程，可另开一个窗口使用`$ watch kubectl get deployment busy`实时查看变化
``` bash
$ kubectl set image deployments/busy busy=busybox:1.29
```

![](../../pics/postPublish.png)

### 4.2. 验证发布
```javascript
检查rollout状态
kubectl -n k8s-ecoysystem-apps rollout status deployments/helloworldapi
检查pod详情
kubectl describe pods -n k8s-ecoysystem-apps
``` bash
# 检查rollout状态
root@kube-aio:~# kubectl rollout status deployments/busy
deployment "busy" successfully rolled out

# 检查pod详情
root@kube-aio:~# kubectl describe pod busy-665cdb7b-44jnt |grep Image
Image: busybox:1.29
Image ID: docker-pullable://busybox@sha256:cb63aa0641a885f54de20f61d152187419e8f6b159ed11a251a09d115fdff9bd
```

![](../../pics/validatePublish.png)

从上图可以看到，镜像已经升级到v2.3版本
从上面可以看到，镜像已经升级到1.29版本
### 4.3. 回滚发布
```javascript
kubectl -n k8s-ecoysystem-apps rollout undo deployments/helloworldapi
``` bash
# 回滚发布
root@kube-aio:~# kubectl rollout undo deployments/busy
deployment.apps "busy"

# 回滚完成
root@kube-aio:~# kubectl rollout status deployments/busy
deployment "busy" successfully rolled out

# 镜像又回退到1.28.4 版本
root@kube-aio:~# kubectl describe pod busy-794c95f5d7-4x9bn |grep Image
Image: busybox:1.28.4
Image ID: docker-pullable://busybox@sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47
```

![](../../pics/rollbackPublish.png)

到目前为止，整个滚动发布工作就圆满完成了！！！
**那么如果我们想回滚到指定版本呢？答案是k8s完美支持，并且还可以通过资源文件进行配置保留的历史版次量**。由于篇幅有限，感兴趣的朋友，可以自己下去实战，回滚命令如下：
```javascript
kubectl -n k8s-ecoysystem-apps rollout undo deployment/helloworldapi --to-revision=<版次>
kubectl rollout undo deployment/busy --to-revision=<版次>
```
## 5、原理
k8s精确地控制着整个发布过程，分批次有序地进行着滚动更新，直到把所有旧的副本全部更新到新版本。实际上，k8s是通过两个参数来精确地控制着每次滚动的pod数量：

>* **`maxSurge` 滚动更新过程中运行操作期望副本数的最大pod数，可以为绝对数值(eg：5)，但不能为0；也可以为百分数(eg：10%)。默认为25%。**
>* **`maxUnavailable` 滚动更新过程中不可用的最大pod数，可以为绝对数值(eg：5)，但不能为0；也可以为百分数(eg：10%)。默认为25%。**
如果未指定这两个可选参数，则k8s会使用默认配置：
```javascript
kubectl -n k8s-ecoysystem-apps get deployment helloworldapi -o yaml
>* **`maxSurge` 滚动更新过程中运行操作期望副本数的最大pod数，可以为绝对数值(eg：5)，但不能为0；也可以为百分数(eg：10%)。**
>* **`maxUnavailable` 滚动更新过程中不可用的最大pod数，可以为绝对数值(eg：5)，但不能为0；也可以为百分数(eg：10%)。**
如果未指定这两个可选参数，则k8s会使用默认配置：
``` bash
root@kube-aio:~# kubectl get deploy busy -o yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "3"
creationTimestamp: 2018-08-19T02:42:56Z
generation: 3
labels:
run: busy
name: busy
namespace: default
resourceVersion: "199461"
selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/busy
uid: 93fde307-a359-11e8-a93b-525400c61543
spec:
progressDeadlineSeconds: 600
replicas: 10
revisionHistoryLimit: 10
selector:
matchLabels:
run: busy
strategy:
rollingUpdate:
maxSurge: 1 # 滚动更新中最多超过预期值的 pod数
maxUnavailable: 1 # 滚动更新中最多不可用的 pod数
type: RollingUpdate
...
```

![](../../pics/publishDefaulConfig.png)

### 5.1. 浅析部署概况
![](../../pics/theory-dep-summary.png)

``` bash
# 初始状态
root@kube-aio:~# kubectl get deploy busy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
busy 10 10 10 10 1h

# 再做一遍回退
root@kube-aio:~# kubectl rollout undo deploy busy
deployment.apps "busy"

# 更新过程1
root@kube-aio:~# kubectl get deploy busy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
busy 10 11 2 9 1h

# 更新过程2
root@kube-aio:~# kubectl get deploy busy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
busy 10 11 4 9 1h

# 更新过程3
root@kube-aio:~# kubectl get deploy busy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
busy 10 11 6 9 1h

# 更新结束
root@kube-aio:~# kubectl get deploy busy
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
busy 10 10 10 10 1h
```
>* `DESIRED`   最终期望处于READY状态的副本数  
>* `CURRENT` 当前的副本总数
>* `UP-TO-DATE` 当前完成更新的副本数
>* `AVAILABLE` 当前可用的副本数
当前的副本总数 = 10 + 10 * 25% = 13，所以CURRENT为13。
当前可用的副本数 = 10 - 10 * 25% = 8，所以AVAILABLE为8。
当前的副本总数：10(DESIRED) + 1(maxSurge) = 11，所以CURRENT为11。
当前可用的副本数：10(DESIRED) - 1(maxUnavailable) = 9，所以AVAILABLE为9。

### 5.2. 浅析部署详情
```javascript
kubectl -n k8s-ecoysystem-apps describe deployment helloworldapi
```
![](../../pics/theory-dep-detail.png)

整个滚动过程是通过控制两个副本集来完成的，新的副本集：helloworldapi-6564f59f66；旧的副本集：helloworldapi-6f4959c8c7 。
``` bash
root@kube-aio:~# kubectl describe deploy busy
Name: busy
Namespace: default
CreationTimestamp: Sun, 19 Aug 2018 12:27:19 +0800
Labels: run=busy
Annotations: deployment.kubernetes.io/revision=2
Selector: run=busy
Replicas: 10 desired | 10 updated | 10 total | 10 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 1 max unavailable, 1 max surge
Pod Template:
Labels: run=busy
Containers:
busy:
Image: busybox:1.29
Port: <none>
Host Port: <none>
Args:
sleep
3600000
Environment: <none>
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: busy-84cb46955d (10/10 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 1m deployment-controller Scaled up replica set busy-9669c8599 to 10
Normal ScalingReplicaSet 46s deployment-controller Scaled up replica set busy-84cb46955d to 1
Normal ScalingReplicaSet 46s deployment-controller Scaled down replica set busy-9669c8599 to 9
Normal ScalingReplicaSet 46s deployment-controller Scaled up replica set busy-84cb46955d to 2
Normal ScalingReplicaSet 43s deployment-controller Scaled down replica set busy-9669c8599 to 8
Normal ScalingReplicaSet 43s deployment-controller Scaled up replica set busy-84cb46955d to 3
Normal ScalingReplicaSet 43s deployment-controller Scaled down replica set busy-9669c8599 to 7
Normal ScalingReplicaSet 43s deployment-controller Scaled up replica set busy-84cb46955d to 4
Normal ScalingReplicaSet 40s deployment-controller Scaled down replica set busy-9669c8599 to 6
Normal ScalingReplicaSet 28s (x12 over 40s) deployment-controller (combined from similar events): Scaled down replica set busy-9669c8599 to 0
```
整个滚动过程是通过控制两个副本集来完成的，新的副本集：busy-84cb46955d；旧的副本集：busy-9669c8599 。
理想状态下的滚动过程：
>1. 创建了一个新的副本集，并为其分配3个新版本的pod，使副本总数达到13，一切正常。
>2. 通知旧副本集，销毁2个旧版本的pod，使可用副本总数保持到8，一起正常。
>3. 当两个副本销毁成功后，通知新副本集，再新增2个新版本的pod，使副本总数达到13，一切正常。
>1. 创建新副本集，并为其分配1个新版本的pod。
>2. 通知旧副本集，销毁1个旧版本的pod。
>3. 当旧副本销毁成功后，通知新副本集，再新增1个新版本的pod；当新副本创建成功后，通知旧副本再减少1个pod。
>只要销毁成功，新副本集就会创造新的pod，一直循环，直到旧的副本集pod数量为0。
### 5.4 总结
**`无论理想还是不理想，k8s最终都会使应用程序全部更新到期望状态，都会始终保持最大的副本总数和可用副本总数的不变性！！！`**
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