Golang v2 environment -- runtime and builder (#427)

v2 environment for Go; includes runtime and builder.

environments/go/server.go

@@ -1,9 +1,12 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"os"
+	"path/filepath"
 	"plugin"
 
 	"github.com/fission/fission/environments/go/context"
@@ -13,14 +16,52 @@ const (
 	CODE_PATH = "/userfunc/user"
 )
 
+type (
+	FunctionLoadRequest struct {
+		// FilePath is an absolute filesystem path to the
+		// function. What exactly is stored here is
+		// env-specific. Optional.
+		FilePath string `json:"filepath"`
+
+		// FunctionName has an environment-specific meaning;
+		// usually, it defines a function within a module
+		// containing multiple functions. Optional; default is
+		// environment-specific.
+		FunctionName string `json:"functionName"`
+
+		// URL to expose this function at. Optional; defaults
+		// to "/".
+		URL string `json:"url"`
+	}
+)
+
 var userFunc http.HandlerFunc
 
-func loadPlugin() http.HandlerFunc {
-	p, err := plugin.Open(CODE_PATH)
+func loadPlugin(codePath, entrypoint string) http.HandlerFunc {
+
+	// if codepath's a directory, load the file inside it
+	info, err := os.Stat(codePath)
 	if err != nil {
 		panic(err)
 	}
-	sym, err := p.Lookup("Handler")
+	if info.IsDir() {
+		files, err := ioutil.ReadDir(codePath)
+		if err != nil {
+			panic(err)
+		}
+		if len(files) == 0 {
+			panic("No files to load")
+		}
+		fi := files[0]
+		codePath = filepath.Join(codePath, fi.Name())
+	}
+
+	fmt.Printf("loading plugin from %v\n", codePath)
+	p, err := plugin.Open(codePath)
+	if err != nil {
+		panic(err)
+	}
+	sym, err := p.Lookup(entrypoint)
 	if err != nil {
 		panic("Entry point not found")
 	}
@@ -44,7 +85,7 @@ func loadPlugin() http.HandlerFunc {
 
 func specializeHandler(w http.ResponseWriter, r *http.Request) {
 	if userFunc != nil {
-		w.WriteHeader(400)
+		w.WriteHeader(http.StatusBadRequest)
 		w.Write([]byte("Not a generic container"))
 		return
 	}
@@ -61,12 +102,48 @@ func specializeHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	fmt.Println("Specializing ...")
-	userFunc = loadPlugin()
+	userFunc = loadPlugin(CODE_PATH, "Handler")
+	fmt.Println("Done")
+}
+
+func specializeHandlerV2(w http.ResponseWriter, r *http.Request) {
+	if userFunc != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte("Not a generic container"))
+		return
+	}
+
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+	var loadreq FunctionLoadRequest
+	err = json.Unmarshal(body, &loadreq)
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	_, err = os.Stat(loadreq.FilePath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			w.WriteHeader(http.StatusNotFound)
+			w.Write([]byte(CODE_PATH + ": not found"))
+			return
+		} else {
+			panic(err)
+		}
+	}
+
+	fmt.Println("Specializing ...")
+	userFunc = loadPlugin(loadreq.FilePath, loadreq.FunctionName)
 	fmt.Println("Done")
 }
 
 func main() {
 	http.HandleFunc("/specialize", specializeHandler)
+	http.HandleFunc("/v2/specialize", specializeHandlerV2)
 
 	// Generic route -- all http requests go to the user function.
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {