Understanding Service Mesh and the Sidecar Pattern: Benefits and Use Cases

Service Mesh is a hot topic today. In particular, the Istio project, launched jointly by Google, IBM, and Lyft, combines service discovery, traffic management, policy enforcement, and monitoring/tracing, making it a leading Service Mesh solution.

When Service Mesh is mentioned, the term Sidecar often appears. The Sidecar pattern (called 挎斗模式 in Chinese, referring to the sidecar of a motorcycle) involves deploying part of an application’s components in a separate process or container to provide isolation and encapsulation. The Sidecar shares the same lifecycle as the main application, being created and destroyed together.

In a design without Sidecar, service discovery, circuit breaking, and other common services run in the same process as the business logic. While this allows efficient resource sharing, the tight coupling reduces isolation, so unrelated modules can affect business modules, and the coupling often forces all modules to be written in the same programming language.

Applying the Sidecar pattern moves certain capabilities to an independent process or container. A common example is placing an NGINX reverse proxy in front of a Node.js service, which is a practical Sidecar implementation.

The Sidecar pattern is typically used together with containers.

Microsoft’s article provides a comprehensive overview of the Sidecar pattern’s background, the problems it addresses, its advantages and disadvantages, and lists scenarios where it is appropriate. Readers are encouraged to consult the original article for more details.