Added first proto file layout. Added first implementation of golang sdk layout. Implemented plugin system

Author: michelvocks

README.md

@@ -1,2 +1 @@
 # Gaia
-Build powerful pipelines with pure Go

plugin/grpc.go

@@ -0,0 +1,51 @@
+package plugin
+
+import (
+	"context"
+
+	plugin "github.com/hashicorp/go-plugin"
+	"github.com/michelvocks/gaia/proto"
+	"google.golang.org/grpc"
+)
+
+// PluginGRPC is the Gaia plugin interface used for communication
+// with the plugin.
+type PluginGRPC interface {
+	GetJobs() (*proto.Plugin_GetJobsClient, error)
+	ExecuteJob(job *proto.Job) (*proto.Empty, error)
+}
+
+// GRPCClient represents gRPC client
+type GRPCClient struct {
+	client proto.PluginClient
+}
+
+// PluginGRPCImpl represents the plugin implementation on client side.
+type PluginGRPCImpl struct {
+	Impl PluginGRPC
+	plugin.NetRPCUnsupportedPlugin
+}
+
+// GRPCServer is needed here to implement hashicorp
+// plugin.Plugin interface. Real implementation is
+// in the plugin(s).
+func (p *PluginGRPCImpl) GRPCServer(s *grpc.Server) error {
+	// Real implementation defined in plugin
+	return nil
+}
+
+// GRPCClient is the passing method for the gRPC client.
+func (p *PluginGRPCImpl) GRPCClient(c *grpc.ClientConn) (interface{}, error) {
+	return &GRPCClient{client: proto.NewPluginClient(c)}, nil
+}
+
+// GetJobs requests all jobs from the plugin.
+// We get a stream of proto.Job back.
+func (m *GRPCClient) GetJobs() (proto.Plugin_GetJobsClient, error) {
+	return m.client.GetJobs(context.Background(), &proto.Empty{})
+}
+
+// ExecuteJob triggers the execution of the given job in the plugin.
+func (m *GRPCClient) ExecuteJob(job *proto.Job) (*proto.JobResult, error) {
+	return m.client.ExecuteJob(context.Background(), job)
+}

plugin/plugin.go

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+package plugin
+
+import (
+	"errors"
+	"os/exec"
+
+	plugin "github.com/hashicorp/go-plugin"
+	"github.com/michelvocks/gaia/proto"
+)
+
+const (
+	pluginMapKey = "plugin"
+)
+
+var handshake = plugin.HandshakeConfig{
+	ProtocolVersion: 1,
+	MagicCookieKey:  "GAIA_PLUGIN",
+	// This cookie should never be changed again
+	MagicCookieValue: "FdXjW27mN6XuG2zDBP4LixXUwDAGCEkidxwqBGYpUhxiWHzctATYZvpz4ZJdALmh",
+}
+
+var pluginMap = map[string]plugin.Plugin{
+	pluginMapKey: &PluginGRPCImpl{},
+}
+
+// Plugin represents a single plugin instance which uses gRPC
+// to connect to exactly one plugin.
+type Plugin struct {
+	// Client instance used to open gRPC connections.
+	client *plugin.Client
+
+	// Interface to the connected plugin.
+	pluginConn PluginGRPC
+}
+
+// NewPlugin creates a new instance of Plugin.
+// One Plugin instance represents one connection to a plugin.
+func NewPlugin(c *exec.Cmd) *Plugin {
+	// Allocate
+	p := &Plugin{}
+
+	// Get new client
+	p.client = plugin.NewClient(&plugin.ClientConfig{
+		HandshakeConfig:  handshake,
+		Plugins:          pluginMap,
+		Cmd:              c,
+		AllowedProtocols: []plugin.Protocol{plugin.ProtocolGRPC},
+	})
+
+	return p
+}
+
+// Connect starts the plugin, initiates the gRPC connection and looks up the plugin.
+// It's up to the caller to call plugin.Close to shutdown the plugin
+// and close the gRPC connection.
+func (p *Plugin) Connect() error {
+	// Connect via gRPC
+	gRPCClient, err := p.client.Client()
+	if err != nil {
+		return err
+	}
+
+	// Request the plugin
+	raw, err := gRPCClient.Dispense(pluginMapKey)
+	if err != nil {
+		return err
+	}
+
+	// Convert plugin to interface
+	if pC, ok := raw.(PluginGRPC); ok {
+		p.pluginConn = pC
+		return nil
+	}
+
+	return errors.New("plugin is not compatible with Gaia plugin interface")
+}
+
+// Execute triggers the execution of one single job
+// for the given plugin.
+func (p *Plugin) Execute(j *proto.Job) error {
+	_, err := p.pluginConn.ExecuteJob(j)
+	return err
+}
+
+// Close shutdown the plugin and kills the gRPC connection.
+// Remember to call this when you call plugin.Connect.
+func (p *Plugin) Close() {
+	// We start the kill command in a goroutine because kill
+	// is blocking until the subprocess successfully exits.
+	// The user should not notice the stopping process.
+	go func() {
+		p.client.Kill()
+	}()
+}

proto/README.md

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+# proto
+This folder contains gRPC proto files and their generated language defintions.
+
+You can use protoc to compile these on your own:
+`protoc -I ./ ./plugin.proto --go_out=plugins=grpc:./`