docs: update blue green update document

[Rory-Z]

Summary by CodeRabbit

• Documentation
  • Revised English and Chinese documents on blue-green deployment for EMQX, improving clarity and usability.
  • Enhanced background sections to detail limitations of traditional rolling updates.
  • Updated steps for creating new Pods and redirecting service traffic during upgrades.
  • Introduced state diagrams for clearer visual representation of the upgrade process.
  • Expanded configuration examples and monitoring sections to provide comprehensive user guidance.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 76.04%. Comparing base (75eb1ef) to head (d43a316).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1081      +/-   ##
==========================================
- Coverage   76.27%   76.04%   -0.23%     
==========================================
  Files          69       69              
  Lines        6250     6250              
==========================================
- Hits         4767     4753      -14     
- Misses       1245     1255      +10     
- Partials      238      242       +4     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[coderabbitai[bot]]

Walkthrough

The pull request involves updates to the documentation for the blue-green deployment strategy of the EMQX cluster. Changes include enhanced clarity in the task objectives, background, and solution sections, with a focus on creating new Pods instead of clusters. The upgrade process has been reformatted for readability, and state diagrams have replaced previous diagrams to illustrate the upgrade steps. Configuration examples have been updated, and a new monitoring section has been added to provide tools for tracking connection metrics during the upgrade.

Changes

File Path	Change Summary
docs/en_US/tasks/configure-emqx-blueGreenUpdate.md	Revised for clarity on blue-green deployment, expanded background, restructured solution, added state diagram, updated deployment commands, and added monitoring section.
docs/zh_CN/tasks/configure-emqx-blueGreenUpdate.md	Improved explanation of blue-green deployment, expanded background, restructured solution, added state diagram, updated configuration examples, and expanded monitoring section.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant EMQX Cluster
    participant New Pods
    participant Old Pods

    User->>EMQX Cluster: Initiate Upgrade
    EMQX Cluster->>New Pods: Create New Pods
    New Pods->>EMQX Cluster: Join Existing Cluster
    EMQX Cluster->>User: Redirect Traffic to New Pods
    User->>Old Pods: Gradually Remove Old Pods
    Old Pods->>EMQX Cluster: Evacuate Connections
    EMQX Cluster->>User: Upgrade Complete

🐇 "In the garden where upgrades bloom,
New Pods arise, dispelling gloom.
Old ones fade, as traffic flows,
With YAML guides, the process grows.
Monitoring metrics, clear as day,
Blue-green magic, hip-hip-hooray!" 🌼

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[Rory-Z]

should we suggest another architecture which do not serve MQTT traffic on core nodes ?

In this document, just deployment only core nodes cluster, should I change cluster to core + repl cluster ?

[zmstone]

should I change cluster to core + repl clus

but I can see replicant node in the flow

HasReplNode --> SelectOldestReplPod: Has EMQX replicant node pod