Скачать или смотреть Resolving Multiple DataSources in Spring Boot Applications

Discover effective ways to manage `multiple DataSources` across dependencies in Spring Boot applications, ensuring seamless connectivity between them.
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This video is based on the question https://stackoverflow.com/q/69257110/ asked by the user 'Tarun Thapa' ( https://stackoverflow.com/u/8237651/ ) and on the answer https://stackoverflow.com/a/69263063/ provided by the user 'William Andrés Bernal' ( https://stackoverflow.com/u/6038682/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Managing Multiple DataSources in Spring Boot Applications

When you're working with complex applications composed of multiple Spring Boot services, you might find yourself needing to manage multiple DataSources effectively. This scenario is especially common when you have one application (let's call it App1) that depends on another (let's call this one App2) for certain functionalities. Both applications may need to communicate with different databases, which could lead to configuration challenges.

In this guide, we'll explore a situation where App1 and App2 need to work together, leveraging multiple DataSources, and we'll offer a strategic solution to address this issue.

The Challenge: Configuring DataSources

In our scenario, App1 and App2 each have their own configurations for accessing a PostgreSQL database. Here’s a breakdown:

App1 Configuration

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App1's application.properties:

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App2 Configuration

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App2's application.properties:

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The conflict

As highlighted, App2's DataSource is marked as @ Primary, which is required to override the default Spring DataSource. This approach, however, presents a problem when you try to configure App1 because it, too, needs its own DataSource which cannot be designated as primary due to the existing configuration in App2.

The Solution: Conditional Bean Configuration

To resolve this conflict and effectively manage both DataSources, you can leverage Spring's conditional bean configuration capabilities. By using annotation conditions, you can define which DataSource should be used based on your application’s configuration.

Implementing the Solution

Add Conditional Annotations: You can wrap your DataSource configuration with a conditional annotation to selectively provide the required DataSource based on your needs. Here’s how you can do it:

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Configuring Application Properties:
Ensure that your configuration properties (application.properties) define flags that determine when each module should be enabled.

Example:

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By implementing conditional DataSource beans, you provide flexibility in how your applications interact with their respective databases, without stepping into configuration conflicts.

Conclusion

Managing multiple DataSources across different Spring Boot applications can seem daunting at first. However, with the right configuration techniques, including conditional bean management, you can create a robust architecture that allows your applications to operate seamlessly.

Utilizing strategies like @ ConditionalOnExpression can significantly enhance your applications' ability to manage complex data interactions without running into configuration issues.

Feel free to share your experiences or questions regarding managing multiple DataSources within your applications!