Point-to-point Traffic Redirection to a Single Machine (e.g., Troubleshooting Issues)

Automatic address discovery and load balancing mechanisms have many advantages; they make it possible to build scalable distributed microservices systems. However, this dynamic traffic allocation also brings a lot of complexity. A typical issue is that we can no longer predict which provider machine a request will hit. Yet, being able to expect or control requests to a specific provider machine can be very useful in certain scenarios. For instance, when developers troubleshoot complex issues in testing or production environments, reliably reproducing issues on a specific machine can greatly aid in final problem resolution.

Before You Begin

Task Details

In this task, we will use the User service as an example, redirecting all calls to the user details method UserService#getInfo from the Frontend application to a fixed instance.

host1.png

Redirect User Details Service Calls to a Fixed Machine

First, determine the actual list of machines that deploy the User application.

  1. $ kubectl get pods -n dubbo-demo
  2. # list result here

Set conditional routing rules for the getInfo method call of the org.apache.dubbo.samples.UserService, forwarding all calls of this method to a specified machine.

Steps

  1. Open the Dubbo Admin console.
  2. In the left navigation bar, select【Service Governance】>【Conditional Routing】.
  3. Click “Create” and enter the service org.apache.dubbo.samples.UserService.

Admin screenshot for specifying machine flow configuration

Open the machine logs and refresh the page to trigger user detail service calls. You can see that only the specified instance in the rules keeps refreshing the following log:

  1. Received getInfo request......

Rule Explanation

Rule Key: org.apache.dubbo.samples.UserService

Rule Body

  1. configVersion: v3.0
  2. enabled: true
  3. force: false
  4. conditions:
  5.   - 'method=getInfo => host = {your ip address}'

Replace {your ip address} with the actual deployment address of User.

Cleanup

To avoid affecting other tasks, delete or disable the conditional routing rules just configured through Admin.

Other Considerations

In production, redirecting traffic to fixed machines should involve safety assessments to avoid overloading a single machine, which can affect system stability. Additionally, in a cloud-native environment, IP addresses can change more frequently and may become invalid. Be sure to promptly clean up routing rules bound to specific IPs.

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Last modified September 30, 2024: Update & Translate Overview Docs (#3040) (d37ebceaea7)