Image Sink

The image sink saves binary image data to a specified directory.

Compile and Deploy the Plugin

Run the following commands to compile and install the plugin:

cd $rekuiper_src
go build -trimpath --buildmode=plugin -o plugins/sinks/Image.so extensions/sinks/image/image.go
cp plugins/sinks/Image.so $rekuiper_install/plugins/sinks

Restart the rekuiper server to activate the plugin.

Properties

Property name	Optional	Description
path	false	Target directory path for saved images, such as ./tmp. Do not use the same directory across different rules to prevent file deletion conflicts.
format	false	Image file format: jpeg or png.
maxAge	true	Maximum retention time in hours. Default: 72 (3 days).
maxCount	true	Maximum number of stored image files. Default: 1000. rekuiper deletes older images when this threshold is exceeded. Evaluated with maxAge by using logical OR.

Other common sink properties are supported. Refer to sink common properties for more information.

Usage Example

The following rule receives images and saves them to the /tmp directory. If the image count exceeds 1000, rekuiper deletes the oldest images. If images remain for more than 72 hours, rekuiper deletes expired files:

{
  "sql": "SELECT * from demo",
  "actions": [
    {
      "image": {
        "path": "/tmp",
        "format": "png",
        "maxCount": 1000,
        "maxAge": 72
      }
    }
  ]
}

Demonstration

The following example uses the zmq source to receive image data and the image sink to store images in the specified directory:

curl http://127.0.0.1:9081/streams -X POST -d '{"sql":"create stream s(image bytea) WITH (DATASOURCE = \"\", FORMAT = \"binary\", TYPE = \"zmq\");"}'

curl http://127.0.0.1:9081/rules -X POST -d '{"id":"r","sql":"SELECT * FROM s","actions":[{"image":{"path":"./tmp","format":"png"}}]}'