Go Native Plugin
The Go language plugin system offers a flexible way to extend functionalities. eKuiper allows user to customize the different kinds of extensions by the native golang plugin system.
- The source extension is used for extending different stream sources, such as consuming data from other message brokers. eKuiper has built-in source support for MQTT broker.
- Sink/Action extension is used for extending pub/push data to different targets, such as database, another message system, web interfaces or file systems. Built-in action is supported in eKuiper, see MQTT & log files.
- Functions extension allows user to extend different functions that are used in SQL. Built-in functions are supported in eKuiper, see functions.
Please read the following to learn how to implement different extensions.
Use Cases and Limitations
Extending functionalities using native plugins is relatively complex, requiring users to write code and compile it themselves, which incurs certain development costs. The scenarios for using native plugins include:
- Needing to extend sources or sinks
- Scenarios with high performance requirements
Due to the limitations of the Go language plugins themselves, the plugin and the main program need to use exactly the same compilation environment, including but not limited to:
- Go language version
- Dependency module versions and even paths
- Same operating system and CPU architecture
Starting from version v2.0, plugins no longer need to depend on the eKuiper main project, instead, only depend on the plugin interface sub-project github.com/lf-edge/ekuiper/contract/v2. Therefore, as long as the plugin uses the same Go language version and contract dependencies as the eKuiper project, it can be used across different eKuiper versions without the need to recompile for each version.
Development
To address the limitations of Go language plugins, users need to follow certain guidelines when developing and deploying extensions, ensuring the correct configuration of the development environment. Plugin development involves implementing specific interfaces according to the plugin type and exporting implementations with specific names. For more details, please refer to Plugin Development.
How Plugins Work
After completing the plugin development, users can package the .so file and corresponding configuration files into a zip. Then, they can upload and install the plugin via the API. The installed plugin will save the so file to the file system, specifically in the plugins directory under the corresponding sources/sinks/functions folders. When eKuiper starts, it will read the corresponding directories under plugins, search for so files, and load the plugins of the corresponding type based on the folder they are in. If there is an error in the plugin implementation, such as incorrect interface implementation or mismatched compilation versions, the plugin loading failure information will be written to the log.
Note: The plugin .so file cannot be changed after loading. Updated plugins require a restart of eKuiper to take effect.
Users can manage plugins through the API for querying and management. For more details, please refer to Plugin API.