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Multiple data sources

Multi-DataSource Plugin

Starting from version 2.2.0, Nacos supports the injection of multi-datasource implementation plugins via the SPI (Service Provider Interface) mechanism. By including the corresponding datasource implementation, users can select and load the desired plugin at startup by configuring the spring.datasource.platform property in the application.properties file.

This document provides a detailed guide on how to implement a multi-datasource plugin and how to enable it.

Note: The multi-datasource plugin feature is currently in the Beta stage. API and interface definitions may undergo significant changes in future updates. Please ensure your plugin is compatible with your specific Nacos version.

Architecture Evolution

Original Implementation

In the legacy Config module, all SQL operations were executed by using JdbcTemplate with hardcoded SQL statements. This resulted in high coupling between SQL logic and business logic, with support limited strictly to Derby and MySQL.

Plugin-based Implementation

The current multi-datasource plugin utilizes the SPI mechanism to abstract SQL operations into multiple Mapper interfaces based on database tables. Implementations of these interfaces are then written to accommodate the SQL dialects of different databases.

Nacos provides default Mapper implementations for Derby and MySQL. Support for other databases requires users to load them via the datasource plugin.

How to Use

  1. Check Support: Verify if Nacos currently supports your required datasource. Nacos provides Derby and MySQL implementations by default. If your database is not supported, refer to the “Developer Guide” below to develop or contribute a plugin.

  2. Configuration: * Set spring.datasource.platform to the name of your specific datasource in application.properties.

    • Configure db.pool.config.driverClassName with the appropriate database driver.
    • Configure the remaining datasource connection parameters.

  3. Build and Run: Compile and run Nacos to enable the new datasource.

  4. Deployment: Place the compiled plugin JAR into the plugins directory under the Nacos root folder. Nacos will load it automatically at startup. (If using a different directory, append the path to the startup command: -Dloader.path={TARGET_PATH}).

Developer Guide: How to Develop a Plugin

  1. Dependency: Add the nacos-datasource-plugin dependency to your project.

  2. Implement Mappers: Implement the specific SQL methods within the Mapper interfaces located in the com.alibaba.nacos.plugin.datasource.mapper package. This primarily involves handling dialect differences such as pagination. You can refer to the existing Derby and MySQL implementations in com.alibaba.nacos.plugin.datasource.impl.

Table-to-Mapper Mapping Reference:

Database TableMapper Interface
config_info_aggrConfigInfoAggrMapper
config_info_betaConfigInfoBetaMapper
config_info_grayConfigInfoGrayMapper
config_infoConfigInfoMapper
config_info_tagConfigInfoTagMapper
config_tags_relationConfigTagsRelationMapper
group_capacityGroupCapacityMapper
his_config_infoHistoryConfigInfoMapper
  1. SPI Configuration: Create an SPI configuration file named com.alibaba.nacos.plugin.datasource.mapper.Mapper. List your implementation classes within this file (refer to the config module’s Derby/MySQL SPI files for examples).
  2. Integration: Users can now achieve database-specific operations by depending on this plugin.
  3. Compile: Build the project.

Compilation

Before compiling the plugin, you must compile nacos and install it to your local Maven repository.

  1. git clone git@github.com:alibaba/nacos.git

  2. cd nacos && mvn -B clean package install -Dmaven.test.skip=true

    Note: If the revision variable fails to resolve, please update Maven to the latest version.

  3. git clone {Your Datasource Plugin Git URL}

  4. mvn install

Recommendation: Upload the compiled artifact to your organization’s internal Maven repository.

Roadmap

Future updates will focus on:

  • Further refining SQL statements to reduce redundancy and improve compatibility with dynamic SQL.

  • Extracting difference lists between various datasources and allowing replacement via configuration files or classes to simplify plugin development.

Other Implementations

For implementations of other datasources (e.g., PostgreSQL, Oracle, etc.), please refer to the official nacos-plugin repository: