Istio architecture extension mechanism

Any system , With the continuous change of usage scenarios and usage methods , We will face many new challenges at any time . To meet these challenges , It is necessary to establish a complete plug-in mechanism on the premise that the kernel is basically stable , Plug-in users can extend in a customized way , And does not affect the stability of the basic architecture of the system .

Istio As the infrastructure supporting microservice communication , It has very high requirements for scalability , Provides multiple dimensions 、 Multi level plug-in extension mechanism , The general summary is as follows .

1）

Service registry

： Service management , You can provide customized service registry support .

2）

Communication protocol

： Not only support common HTTP The protocol and TCP agreement , It also supports various user-defined protocols .

3）

Link governance

： It not only supports various customized traffic scheduling and traffic management , It can also support users to process requests in a customized way .

4）

Telemetry and statistics

： Supports multiple adapters , And you can easily add new custom adapters .

Istio Through various forms of plug-in mechanisms to achieve a strong extensibility support , Plug ins are actually very simple from the implementation level , It is essentially a hook callback function

, Plug in registration is to hang the hook callback function on the plug-in mechanism , When the event comes , Trigger the call of the callback function . Therefore, the research on plug-in mechanism needs to focus on two points .

1） The abstraction of plug-ins . Abstraction is a basic ability that architects must have , Abstraction is the process of extracting invariance from change . By studying classical Abstract processes , It can provide a reference for the subsequent design of their own plug-in mechanism .

2） Callback and notification mechanism .

Istio Define the basic capabilities of service discovery through the abstract interface of service discovery , The service discovery abstract interface defines a registry to provide basic capabilities , Each registry only needs to implement this interface . Plug in callback and notification mechanism , The service registry provides callback triggering in two directions .

1） Register the registry plug-in to Istio in , You can get specific service discovery capabilities through plug-ins ;

2） Plug ins provide abstract interfaces for service changes ,Istio Reversely register the callback function for notification in the plug-in , When the registry changes , The plug-in will call the pre registered Istio Callback function .

Architecture certainly has many common design ideas and principles , But many architectural design principles are themselves a pair of contradictions , For example, distributed systems CAP、 Performance and efficiency, etc , It is impossible to meet all the design requirements at the same time , Specific scenarios are needed , Make certain compromises and trade-offs .

Architecture design is a balancing process , When all the needs cannot be met , There is no need to treat all needs equally , The essence of architecture design is trade-offs , That is to discover the fundamental needs of the business

, Weigh which needs you really care about , Which requirements can be discarded at present . At the same time, we should also realize that the fundamental needs are not immutable , As time and business change , Fundamental needs may also change .