plugins.go

package gripper

import (
	"context"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"

	"github.com/hashicorp/go-plugin"
	"github.com/kennygrant/sanitize"
	grpc "google.golang.org/grpc"
)

var Handshake = plugin.HandshakeConfig{
	ProtocolVersion:  1,
	MagicCookieKey:   "GRIP_PLUGIN_EXTERNAL_RESOURCE",
	MagicCookieValue: "gripper",
}

type GripPlugin struct {
	plugin.Plugin
	Impl GRIPSourceServer
}

var PluginMap = map[string]plugin.Plugin{
	"gripper": &GripPlugin{},
}

func (p *GripPlugin) GRPCServer(broker *plugin.GRPCBroker, s *grpc.Server) error {
	RegisterGRIPSourceServer(s, p.Impl)
	return nil
}

func (p *GripPlugin) GRPCClient(ctx context.Context, broker *plugin.GRPCBroker, c *grpc.ClientConn) (interface{}, error) {
	return NewGRIPSourceClient(c), nil
}

func LaunchPluginClient(plugindir string, name string, workdir string, params map[string]string) (*plugin.Client, error) {
	name = sanitize.BaseName(name)
	plugPath, err := filepath.Abs(filepath.Join(plugindir, "gripper-"+name))

	if err != nil {
		return nil, fmt.Errorf("plugin %s not found", name)
	}
	if _, err := os.Stat(plugPath); err != nil {
		return nil, fmt.Errorf("plugin %s not found", name)
	}

	confPath := filepath.Join(workdir, "conf.json")
	message, err := json.Marshal(params)
	if err != nil {
		return nil, err
	}
	err = ioutil.WriteFile(confPath, message, 0644)
	if err != nil {
		return nil, err
	}
	client := plugin.NewClient(&plugin.ClientConfig{
		HandshakeConfig:  Handshake,
		Plugins:          PluginMap,
		Cmd:              exec.Command(plugPath, confPath), //FIXME
		AllowedProtocols: []plugin.Protocol{plugin.ProtocolGRPC},
	})
	_, err = client.Start()
	return client, err
}

func GetSourceInterface(client *plugin.Client) (GRIPSourceClient, error) {
	// Connect via GRPC
	rpcClient, err := client.Client()
	if err != nil {
		return nil, err
	}
	// Request the plugin
	raw, err := rpcClient.Dispense("gripper")
	if err != nil {
		return nil, err
	}
	sourceClient := raw.(GRIPSourceClient)
	return sourceClient, nil
}