When to use Shared Libraries in Microservices

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When building microservices, architecture developers must decide whether or not to use shared libraries. Shared libraries can help reduce code duplication and make it easier to update common code across multiple services. Shared Libraries introduce tight coupling between services, making it more difficult to modify or replace individual services without affecting the others.

This blog post will explore when it is appropriate to use shared libraries in microservices and when it is better to avoid them.

Benefits of Shared Libraries in Microservices

There are several benefits to using shared libraries in a microservices architecture:

Code reuse: One of the primary benefits of shared libraries is allowing developers to reuse code across services. This can save time and effort by eliminating the need to write the same code. It can also help ensure that all services use the same code version, which is especially important for security-critical code.
Centralized maintenance: Shared libraries also make it easier to maintain and update common code. Instead of updating the same code in multiple places, developers can make the changes in a single location and automatically propagate the updates to all library services.
Improved consistency: Using shared libraries can also help ensure that all services in the architecture adhere to the same standards and practices. This can improve the system’s consistency and make it easier for developers to understand and work with the code.

Risks of Shared Libraries in Microservices

Despite these benefits, there are also several risks associated with using shared libraries in microservices:

Tight coupling: One of the biggest risks of shared libraries is that they can create tight coupling between services. If a shared library is used by multiple services, changing or updating the library can have unintended consequences for those services. This can make it more difficult to modify or replace individual services without affecting the others.
Dependency issues: Shared libraries can also introduce dependency issues if different services use different versions of the library. This can lead to compatibility issues and make deploying and managing the system more difficult.
Lack of flexibility: Shared libraries can also limit the flexibility of individual services. If a service is tightly coupled to a shared library, it may be more challenging to modify or replace that service without also affecting the library.

When to Use Shared Libraries in Microservices

So when is it appropriate to use shared libraries in a microservices architecture? Here are a few guidelines to consider:

Use shared libraries for code that is likely to be reused across multiple services. For example, if you have a set of utility functions that are likely to be needed by multiple services, it might make sense to put them in a shared library.
Use shared libraries sparingly. While shared libraries can be useful in certain situations, it’s important not to overuse them. The more shared libraries you have, the more tightly coupled your services will become, which can make it more difficult to modify or replace individual services.
Be mindful of dependencies. If you do use shared libraries, be sure to carefully manage dependencies between services and the library. This can help avoid compatibility issues and make it easier to deploy and manage the system.
Consider using a microservices gateway. One way to mitigate the risks of shared libraries is to use a microservices gateway, which acts as an intermediary between the client and the microservices. The gateway can handle tasks such as routing requests, load balancing, and caching, which can help reduce the tight coupling between services.