The plugin package

Learn the basics and limits of the plugin package.

The plugin package

The plugin package lets you load separately compiled Go code (a .so file) at run time and use its functions and variables. It is a way to add features without rebuilding the main program.

p, err := plugin.Open("selam.so")
sym, err := p.Lookup("Selam")

It only works on Linux, FreeBSD and macOS; Windows is not supported.

Limitations

A plugin and the main program must be built with the same Go version and the same dependency versions, or loading fails. A loaded plugin can never be unloaded. That is why many projects prefer systems that talk to separate processes (e.g. HashiCorp go-plugin, gRPC) instead.

Exercise Load a plugin

Call plugin.Open("selam.so"). If there is an error print fmt.Println("yüklenemedi") and return; otherwise print fmt.Println("yüklendi"). (The file doesn't exist here, so the output is yüklenemedi.)

Show example solution

package main

import (
    "fmt"
    "plugin"
)

func main() {
    _, err := plugin.Open("selam.so")
    if err != nil {
        fmt.Println("yüklenemedi")
        return
    }
    fmt.Println("yüklendi")
}

Test yourself

On which system does the plugin package <strong>not</strong> work?
- macOS
- FreeBSD
- Windows
- Linux
Show answer

Windows — Go plugin support is only for Linux, FreeBSD and macOS; on Windows plugin.Open returns an error.

Open a plugin

p, err := plugin.____("eklenti.so")

Show answer

p, err := plugin.Open("eklenti.so")

plugin concepts

.so file

Compiled plugin
plugin.Open

Loading
Lookup

Symbol lookup
Same Go version

Compatibility requirement

Next lesson: Building a plugin

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