A small example application for using plugins in go.
Using plugins, it is possible to add/remove functionality to a compiled go program at runtime.
In this example, I expect that a plugin has a function New (see: cmd/cli/main.go +29).
I also expect that the return value of this New function implements a Module interface (see: pkg/wrapper/module.go). In this application, a Module has needs a fuction called Execute().
If you want to create a new plugin for this application, you have to implement those two functions at a minimum.
Clone and build the example application:
go get -u github.com/xellio/golang-plugin-example
cd $GOPATH/src/github.com/xellio/golang-plugin-example/
make
Run the application:
./bin/modules
Hello from FIRST...
Hello from SECOND...
Hello from THIRD - Written in C...
Hello from FIRST...
Hello from THIRD - Written in C...
Hello from SECOND...
Hello from FIRST...
Hello from SECOND...
Hello from THIRD - Written in C...
...
NOTE: In this example, the plugins were executed in a goroutine - so the order of the output can change.
In the application root ($GOPATH/src/github.com/xellio/golang-plugin-example/) you will find a plugins/ directory, conaining the loaded plugins (.so files):
...
├── plugins
│ ├── first_plugin.so
│ ├── second_plugin.so
│ └── third_plugin.so
...
Removing one of those plugins while running the application will stop executing the removed plugin:
mv ./plugins/second_plugin.so .
Output:
Hello from FIRST...
Hello from THIRD - Written in C...
Hello from SECOND...
Hello from THIRD - Written in C...
Hello from FIRST...
Hello from FIRST...
Hello from THIRD - Written in C...
Hello from THIRD - Written in C...
Hello from FIRST...
(Re)adding a plugin to the plugins/ directory will (re)execute the plugin:
mv ./second_plugin.so ./plugins/
Output:
Hello from THIRD - Written in C...
Hello from FIRST...
Hello from FIRST...
Hello from THIRD - Written in C...
Hello from SECOND...
Hello from FIRST...
Hello from THIRD - Written in C...
Hello from SECOND...