Governing Microservices

Prerequisites

• You can create a microservice in Microservice List from Service Catalog and start the microservice. After the microservice starts, the service instance is registered under the corresponding service based on configurations in the .yaml file.
• If the microservice is not created in advance or has been deleted, the microservice is automatically created when the service instance is registered.
• After a microservice is created, you need to register the service instance before performing the corresponding operation.

Governance Policies

Supports the configuration of policies such as load balancing, rate limiting, fault tolerance, service degradation, circuit breaker, and fault injection. For details, see the following table.

Configuring Load Balancing

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Load Balancing.
6. Click Add. Select the microservices to be governed and select a proper load balancing policy. For details, see the following table.

   Policy	Description
   Round robin	Supports routes according to the location information about service instances.
   Random	Provides random routes for service instances.
   Response time weight	Provides weight routes with the minimum active number (latency) and supports service instances with slow service processing in receiving a small number of requests to prevent the system from stopping response. This load balancing policy is suitable for applications with low and stable service requests.
   Session stickiness	Provides a mechanism on the load balancer. In the specified session stickiness duration, this mechanism allocates the access requests related to the same user to the same instance. Session Stickiness Duration: session hold time. The value ranges from 0 to 86400, in seconds. Failures: number of access failures. The value ranges from 0 to 10. If the upper limit of failures or the session stickiness duration exceeds the specified values, the microservice stops accessing this instance.

7. Click OK to save the settings.

Configuring Rate Limiting

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Rate Limiting.
6. Click Add. The following table describes the configuration items of rate limiting.

   Configuration Item	Description	Value Range
   Object	Other microservices that access the microservice.	You can set the item in the drop-down list box next to Object.
   QPS	Requests generated per second. When the number of requests sent by the rate limiting object to the current service instance exceeds the specified value, the current service instance no longer accepts requests from the rate limiting object.	An integer ranging from 0 to 99999.

   NOTE:

   If a microservice has three instances, the rate limiting of each instance is set to 2700 QPS, then the total QPS is 8100, and rate limiting is triggered only when the QPS exceeds 8100.

7. Click OK to save the settings.

Configuring Service Degradation

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Service Degradation.
6. Click Add. Select a proper policy. The following table describes the configuration items of service degradation.

   Configuration Item	Description
   Object	Microservice to be degraded and the corresponding degradation method.
   Policy	Enable Disable

7. Click OK to save the settings.

Configuring Fault Tolerance

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Fault Tolerance.
6. Click Add. Select a proper policy. The following table describes the configuration items of fault tolerance.

   Configuration Item	Description
   Object	Microservice or method that the application relies on. You can select it from the drop-down list.
   Degradation Mode	Enable: The system processes the service request based on the selected fault tolerance policy when the request sent to the fault tolerance object encounters an error. Disable: The system waits until the timeout interval expires and then returns the failure result even though the service request fails to be implemented.
   Policy NOTE: Set this parameter when Degradation Mode is set to Enable.	Failover The system attempts to reestablish connections on different servers. Failfast The system does not attempt to reestablish a connection. After a request fails, a failure result is returned immediately. Failback The system attempts to reestablish connections on the same server. custom Number of attempts to reestablish connections on the same server Number of attempts to reestablish connections on new servers

7. Click OK to save the settings.

Configuring Circuit Breaker

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Circuit Breaker.
6. Click Add. Select a proper policy. The following table describes the configuration items of circuit breaker.

   Configuration Item	Description
   Object	Microservice or method invoked by the application.
   Trigger Condition	Manual Circuit breaker is triggered immediately and microservice instances are not called. Cancel Circuit breaker taking effect on the microservice instance is canceled and the microservice instance can be called. Automatic Circuit Breaker Time Window: circuit breaker duration. No response is sent within the time window. Failure Rate: failure rate of window requests, which is a triggering condition. Window Requests: number of requests received by the window, which is a triggering condition. Circuit breaker is triggered only when Failure Rate and Window Requests both reach their thresholds.

7. Click OK to save the settings.

Configuring Fault Injection

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Fault Injection.
6. Click Add. Select a proper policy. The following table describes the configuration items of fault injection.

   Configuration Item	Description
   Object	Microservices for which fault injection is required. You can specify a method for this configuration item.
   Type	Type of the fault injected to the microservice. Latency Error
   Protocol	Protocol for accessing the microservice when latency or fault occurs. Rest Highway
   Latency	Latency for accessing a microservice. This parameter is required when Type is set to Latency.
   HTTP Error Code	HTTP error code displayed during microservice access. This parameter is required when Type is set to Error. This error code is an HTTP error code.
   Trigger Probability	Probability of latency or fault occurrence.

7. Click OK to save the settings.

Configuring Blacklist and Whitelist

Based on the public key authentication mechanism, CSE provides the blacklist and whitelist functions. The blacklist and whitelist can be used to control which services can be accessed by microservices.

The blacklist and whitelist take effect only after public key authentication is enabled. For details, see Configuring Public Key Authentication.

1. Log in to ServiceStage and choose Infrastructure > Cloud Service Engines.
2. Click Console of a microservice engine.
3. Choose Service Governance.
4. Click the microservice to be governed.
5. Click Blacklist and Whitelist.
6. Click Add to add a blacklist or whitelist for the application. The following table describes the configuration items of blacklist and whitelist.

   Configuration Item	Description
   Type	Blacklist: Microservices matching the matching rule are not allowed to access the current service. Whitelist: Microservices matching the matching rule are allowed to access the current service.
   Matching Rule	Expressed by a regular expression. For example, if Matching Rule is set to data*, services whose name starts with data in the blacklist cannot access the current service, or services whose name starts with data in the whitelist can access the current service.

7. Click OK to save the settings.

Configuring Public Key Authentication

Public key authentication is a simple and efficient authentication mechanism between microservices provided by CSE. Its security is based on the reliable interaction between microservices and the service center. That is, the authentication mechanism must be enabled between microservices and the service center. The procedure is as follows:

1. When a microservice starts, a key pair is generated and the public key is registered with the service center.
2. Before accessing the provider, the consumer uses its own private key to sign a message.
3. The provider obtains the public key of the consumer from the service center and verifies the signed message.

To enable public key authentication, perform the following steps:

1. Enable public key authentication for both the consumer and provider.

   servicecomb:
     handler:
       chain:
         Consumer:
           default: auth-consumer
         Provider:
           default: auth-provider
2. Add the following dependency to the pom.xml file:

   <dependency> 
       <groupId>org.apache.servicecomb</groupId> 
       <artifactId>handler-publickey-auth</artifactId> 
     </dependency>