component/custom/custom.go

/*
    _____           _____   _____   ____          ______  _____  ------
   |     |  |      |     | |     | |     |     | |       |            |
   |     |  |      |     | |     | |     |     | |       |            |
   | --- |  |      |     | |-----| |---- |     | |-----| |-----  ------
   |     |  |      |     | |     | |     |     |       | |       |
   | ____|  |_____ | ____| | ____| |     |_____|  _____| |_____  |_____


   Licensed under the MIT License <http://opensource.org/licenses/MIT>.

   Copyright © 2020-2025 Microsoft Corporation. All rights reserved.
   Author : <blobfusedev@microsoft.com>

   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in all
   copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE
*/

package custom

import (
	"fmt"
	"os"
	"plugin"
	"strings"
	"time"

	"github.com/Azure/azure-storage-fuse/v2/common/log"
	"github.com/Azure/azure-storage-fuse/v2/exported"
	"github.com/Azure/azure-storage-fuse/v2/internal"
)

func initializePlugins() error {

	// Environment variable which expects file path as a colon-separated list of `.so` files.
	// Example BLOBFUSE_PLUGIN_PATH="/path/to/plugin1.so:/path/to/plugin2.so"
	pluginFilesPath := os.Getenv("BLOBFUSE_PLUGIN_PATH")
	if pluginFilesPath == "" {
		log.Debug("initializePlugins: No plugins to load.")
		return nil
	}

	pluginFiles := strings.Split(pluginFilesPath, ":")

	for _, file := range pluginFiles {
		if !strings.HasSuffix(file, ".so") {
			log.Err("initializePlugins: Invalid plugin file extension: %s", file)
			continue
		}
		log.Info("initializePlugins: loading plugin %s", file)
		startTime := time.Now()
		p, err := plugin.Open(file)
		if err != nil {
			log.Err("initializePlugins: Error opening plugin %s: %s", file, err.Error())
			return fmt.Errorf("error opening plugin %s: %s", file, err.Error())
		}

		getExternalComponentFunc, err := p.Lookup("GetExternalComponent")
		if err != nil {
			log.Err("initializePlugins: GetExternalComponent function lookup error in plugin %s: %s", file, err.Error())
			return fmt.Errorf("GetExternalComponent function lookup error in plugin %s: %s", file, err.Error())
		}

		getExternalComponent, ok := getExternalComponentFunc.(func() (string, func() exported.Component))
		if !ok {
			log.Err("initializePlugins: GetExternalComponent function in %s has some incorrect definition", file)
			return fmt.Errorf("GetExternalComponent function in %s has some incorrect definition", file)
		}

		compName, initExternalComponent := getExternalComponent()
		internal.AddComponent(compName, initExternalComponent)
		log.Info("initializePlugins: Plugin %s loaded in %s", file, time.Since(startTime))
	}
	return nil
}

func init() {
	err := initializePlugins()
	if err != nil {
		log.Err("custom::init : Error initializing plugins: %s", err.Error())
		fmt.Printf("failed to initialize plugin: %s\n", err.Error())
		os.Exit(1)
	}
}