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docs: update blue green update document
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Signed-off-by: Rory Z <[email protected]>
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Rory-Z committed Oct 22, 2024
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147 changes: 77 additions & 70 deletions docs/en_US/tasks/configure-emqx-blueGreenUpdate.md
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Expand Up @@ -18,31 +18,6 @@ This feature only supports `apps.emqx.io/v1beta4 EmqxEnterprise` and `apps.emqx.

2. During the rolling update process, only N - 1 Pods can provide services because it takes some time for new Pods to start up and become ready. This may lead to a decrease in service availability.

```mermaid
timeline
section Update start
Current Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Rolling update
Current Cluster<br>Have Endpoint
: pod-0
: pod-1
Update Cluster<br>Have Endpoint
: pod-2
Current Cluster<br>Have Endpoint
: pod-0
Update Cluster<br>Have Endpoint
: pod-1
: pod-2
section Finish Update
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
```

## Solution

Regarding the issue of rolling updates mentioned in the previous text, EMQX Operator provides a blue-green deployment upgrade solution. When upgrading the EMQX cluster using EMQX custom resources, EMQX Operator will create a new EMQX cluster and redirect the Kubernetes Service to the new EMQX cluster after it is ready. It will then gradually delete Pods from the old EMQX cluster to achieve the purpose of updating the EMQX cluster.
Expand All @@ -51,51 +26,67 @@ When deleting Pods from the old EMQX cluster, EMQX Operator can also take advant

The entire upgrade process can be roughly divided into the following steps:

1. Create a cluster with the same specifications.

2. After the new cluster is ready, redirect the service to the new cluster and remove the old cluster from the service. At this time, the new cluster starts to receive traffic, and existing connections in the old cluster are not affected.

3. (Only supported by EMQX Enterprise Edition) Use EMQX node evacuation function to evacuate connections on each node one by one.

4. Gradually scale down the old cluster to 0 nodes.

1. Create new Pods with the EMQX custom resource, and join the new Pods to the EMQX cluster.
2. After the new Pods are ready, redirect the Service to the new Pods and remove the old Pods from the Service. At this time, the new Pods start to receive traffic, and existing connections in the old Pods are not affected.
3. (Only supported by EMQX Enterprise Edition) Use the EMQX node evacuation function to evacuate connections on each node one by one.
4. Gradually scale down the old Pods to 0.
5. Complete the upgrade.

```mermaid
timeline
section Update start
Current Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Create update cluster
Current Cluster
: pod-0
: pod-1
: pod-2
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Updating cluster
Current Cluster
: pod-0
: pod-1
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
Current Cluster
: pod-0
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Finish Update
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
stateDiagram-v2
[*] --> Step1
Step1: Create new pods
state Step1 {
[*] --> CreateNewPods
CreateNewPods: Create new pods
CreateNewPods --> NewPodsJoinTheCluster
NewPodsJoinTheCluster: New pods join the cluster
NewPodsJoinTheCluster --> WaitNewPodsReady
WaitNewPodsReady: Wait new pods ready
WaitNewPodsReady --> LBServiceSelectNewPods
LBServiceSelectNewPods: Redirect the Service to the new Pods and remove the old Pods from the Service
LBServiceSelectNewPods --> [*]
}
Step1 --> Step2
Step2: Delete old pods
state HasReplNode <<choice>>
state NodeEvacuationToNewPod1 <<choice>>
state NodeEvacuationToNewPod2 <<choice>>
state Step2 {
[*] --> SelectOldestPod
SelectOldestPod: Select oldest pod
SelectOldestPod --> HasReplNode
HasReplNode --> SelectOldestReplPod: Has EMQX's replicant node pod
SelectOldestReplPod: Select oldest EMQX's replicant node pod
SelectOldestReplPod --> NodeEvacuationToNewPod1
NodeEvacuationToNewPod1 --> NodeEvacuationToNewReplPod1: New pods has EMQX's replicant node
NodeEvacuationToNewReplPod1: Node evacuation to new EMQX's replicant node pod
NodeEvacuationToNewReplPod1 --> DeleteThisOldestPod1
NodeEvacuationToNewPod1 --> NodeEvacuationToNewCorePod1: New pods has no EMQX's replicant node
NodeEvacuationToNewCorePod1: Node evacuation to new EMQX's core node pod
NodeEvacuationToNewCorePod1 --> DeleteThisOldestPod1
DeleteThisOldestPod1: Delete this oldest pod
DeleteThisOldestPod1 --> HasReplNode
HasReplNode --> SelectOldestCorePod: Has no EMQX's replicant node pod
SelectOldestCorePod: Select oldest EMQX's core node pod
SelectOldestCorePod --> NodeEvacuationToNewPod2
NodeEvacuationToNewPod2 --> NodeEvacuationToNewReplPod2: New pods has EMQX's replicant node
NodeEvacuationToNewReplPod2: Node evacuation to new EMQX's replicant node pod
NodeEvacuationToNewReplPod2 --> DeleteThisOldestPod2
NodeEvacuationToNewPod2 --> NodeEvacuationToNewCorePod2: New pods has no EMQX's replicant node
NodeEvacuationToNewCorePod2: Node evacuation to new EMQX's core node pod
NodeEvacuationToNewCorePod2 --> DeleteThisOldestPod2
DeleteThisOldestPod2: Delete this oldest pod
DeleteThisOldestPod2 --> [*]
}
Step2 --> Complete
Complete --> [*]
```

## How to update the EMQX cluster through blue-green deployment.
Expand Down Expand Up @@ -131,7 +122,7 @@ spec:

`sessEvictRate`: MQTT Session evacuation rate, only supported by EMQX Enterprise Edition (unit: count/second)。

Save the above content as: `emqx-update.yaml`, execute the following command to deploy EMQX:
Save the above content as: `emqx-update.yaml`, execute the following command to deploy EMQX, in this example, just deploy EMQX core node cluster without replicant node:

```bash
$ kubectl apply -f emqx-update.yaml
Expand Down Expand Up @@ -231,10 +222,26 @@ Output is similar to:
emqx.apps.emqx.io/emqx-ee patched
```

- Check status.
- Check the status of the EMQX core nodes

```bash
kubectl get emqx emqx-ee -o json | jq '.status.coreNodesStatus'
{
"currentReplicas": 2,
"currentRevision": "54fc496fb4",
"readyReplicas": 4,
"replicas": 2,
"updateReplicas": 2,
"updateRevision": "5d87d4c6bd"
}
```

In this example, the old StatefulSet is `emqx-${currentRevision}`, which has 2 pods, and all pods are ready. The new StatefulSet is `emqx-${updateRevision}`, which has 2 pods, and 2 pods are being updated. Then the EMQX Operator will start the node evacuation process.

- Check node evacuations status.

```bash
$ kubectl get emqx emqx-ee -o json | jq ".status.nodEvacuationsStatus"
$ kubectl get emqx emqx-ee -o json | jq ".status.nodeEvacuationsStatus"
[
{
Expand Down
121 changes: 58 additions & 63 deletions docs/zh_CN/tasks/configure-emqx-blueGreenUpdate.md
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Expand Up @@ -17,31 +17,6 @@
1. 在进行滚动更新时，对应的 Service 会同时选中新的和旧的 Pod。这可能导致 MQTT 客户端连接到错误的 Pod 上，从而频繁断开连接并进行重连操作。
2. 在滚动更新过程中，只有 N - 1 个 Pod 能够提供服务，因为新的 Pod 需要一定时间来启动和准备就绪。这可能导致服务的可用性下降。

```mermaid
timeline
section Update start
Current Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Rolling update
Current Cluster<br>Have Endpoint
: pod-0
: pod-1
Update Cluster<br>Have Endpoint
: pod-2
Current Cluster<br>Have Endpoint
: pod-0
Update Cluster<br>Have Endpoint
: pod-1
: pod-2
section Finish Update
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
```

## 解决方案

针对上文提到的滚动更新的问题，EMQX Operator 提供了蓝绿发布的升级方案，通过 EMQX 自定义资源升级 EMQX 集群时，EMQX Operator 会创建新的 EMQX 集群，并在集群就绪后将 Kubernetes Service 指向新的 EMQX 集群，并逐步删除旧的 EMQX 集群的 Pod，从而达到更新 EMQX 集群的目的。
Expand All @@ -50,47 +25,67 @@ timeline

整个升级流程大致可分为以下几步：

1. 创建一个相同规格的集群。
2. 新集群就绪后，将 service 指向新集群，并将旧集群从 service 中摘除，此时新集群开始接受流量，旧集群现有的连接不受影响。
3. （仅支持 EMQX 企业版）通过 EMQX 节点疏散功能，逐个对节点上的连接进行疏散。
4. 将旧的集群逐步缩容到 0 个节点。
1. 使用 EMQX 自定义资源创建新的 Pods，并将新的 Pods 加入 EMQX 集群。
2. 当新的 Pods 就绪后，将 Service 重定向到新的 Pods，并从 Service 中移除旧的 Pods。此时，新的 Pods 开始接收流量，旧的 Pods 中的现有连接不受影响。
3. （仅 EMQX 企业版支持）使用 EMQX 节点疏散功能逐个疏散每个节点上的连接。
4. 逐渐将旧的 Pods 缩减至 0。
5. 完成升级。

```mermaid
timeline
section Update start
Current Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Create update cluster
Current Cluster
: pod-0
: pod-1
: pod-2
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Updating cluster
Current Cluster
: pod-0
: pod-1
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
Current Cluster
: pod-0
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
section Finish Update
Update Cluster<br>Have Endpoint
: pod-0
: pod-1
: pod-2
stateDiagram-v2
[*] --> Step1
Step1: Create new pods
state Step1 {
[*] --> CreateNewPods
CreateNewPods: Create new pods
CreateNewPods --> NewPodsJoinTheCluster
NewPodsJoinTheCluster: New pods join the cluster
NewPodsJoinTheCluster --> WaitNewPodsReady
WaitNewPodsReady: Wait new pods ready
WaitNewPodsReady --> LBServiceSelectNewPods
LBServiceSelectNewPods: Redirect the Service to the new Pods and remove the old Pods from the Service
LBServiceSelectNewPods --> [*]
}
Step1 --> Step2
Step2: Delete old pods
state HasReplNode <<choice>>
state NodeEvacuationToNewPod1 <<choice>>
state NodeEvacuationToNewPod2 <<choice>>
state Step2 {
[*] --> SelectOldestPod
SelectOldestPod: Select oldest pod
SelectOldestPod --> HasReplNode
HasReplNode --> SelectOldestReplPod: Has EMQX's replicant node pod
SelectOldestReplPod: Select oldest EMQX's replicant node pod
SelectOldestReplPod --> NodeEvacuationToNewPod1
NodeEvacuationToNewPod1 --> NodeEvacuationToNewReplPod1: New pods has EMQX's replicant node
NodeEvacuationToNewReplPod1: Node evacuation to new EMQX's replicant node pod
NodeEvacuationToNewReplPod1 --> DeleteThisOldestPod1
NodeEvacuationToNewPod1 --> NodeEvacuationToNewCorePod1: New pods has no EMQX's replicant node
NodeEvacuationToNewCorePod1: Node evacuation to new EMQX's core node pod
NodeEvacuationToNewCorePod1 --> DeleteThisOldestPod1
DeleteThisOldestPod1: Delete this oldest pod
DeleteThisOldestPod1 --> HasReplNode
HasReplNode --> SelectOldestCorePod: Has no EMQX's replicant node pod
SelectOldestCorePod: Select oldest EMQX's core node pod
SelectOldestCorePod --> NodeEvacuationToNewPod2
NodeEvacuationToNewPod2 --> NodeEvacuationToNewReplPod2: New pods has EMQX's replicant node
NodeEvacuationToNewReplPod2: Node evacuation to new EMQX's replicant node pod
NodeEvacuationToNewReplPod2 --> DeleteThisOldestPod2
NodeEvacuationToNewPod2 --> NodeEvacuationToNewCorePod2: New pods has no EMQX's replicant node
NodeEvacuationToNewCorePod2: Node evacuation to new EMQX's core node pod
NodeEvacuationToNewCorePod2 --> DeleteThisOldestPod2
DeleteThisOldestPod2: Delete this oldest pod
DeleteThisOldestPod2 --> [*]
}
Step2 --> Complete
Complete --> [*]
```

## 如何通过蓝绿发布更新 EMQX 集群
Expand Down

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