seperated out boilerplate plugin code

frontend/db.go

@@ -19,8 +19,8 @@ func initDB() {
 	dbcreds := fmt.Sprintf("user=%s password=%s dbname=%s sslmode=disable",
 	dbUser, dbPassword, dbName)
 	db, dberr := sql.Open("postgres", dbcreds)
+	fmt.Println("DB status:", db.Ping())
 	if dberr != nil {
 		log.Fatal(dberr)
 	}
-	defer db.Close()
 }

frontend/plugins/assets/assets.go

@@ -6,24 +6,13 @@ import (
 	"strings"
 	"core-networkmanager/frontend/plugins"
 )
-//Page struct to hold per-page data
-type page struct {
-	Location string
-	Name string
-}
-//Plugin implements plugin interface
-type Plugin struct {}
 
-func init() {
-	plugins.RegisterPlugin("assets", &Plugin{})
-}
-
-//Activate sets up endpoints and such
-func (p Plugin ) Activate () {
+func setup() bool {
 	fileserver := http.FileServer(FileSystem{http.Dir("./assets")})
 	plugins.RegisterEndpoint("/assets/", http.StripPrefix("/assets", fileserver).ServeHTTP)
+	return true
 }
-//FileSystem implements http.Filesystem, with Open() that doesnt allow Dirs
+	//FileSystem implements http.Filesystem, with Open() that doesnt allow Dirs
 type FileSystem struct {
 	fs http.FileSystem
 }

frontend/plugins/assets/plugin.go

@@ -0,0 +1,32 @@
+package assets
+import (
+	"sync"
+	"core-networkmanager/frontend/plugins"
+)
+
+var (
+	mux sync.Mutex
+	active bool
+)
+
+//init registers the plugin as available with Plugin manager
+func init() {
+	plugins.RegisterPlugin("assets", &plugin{})
+}
+
+//plugin struct that for the plugin to impliment required and optional interfaces as defined in Plugin package
+type plugin struct {}
+
+//Activate sets up endpoints and databases, and any other initialization 
+func (p plugin ) Activate () {
+	if(!active) {
+		mux.Lock()
+		active = setup()
+		mux.Unlock()
+	}
+}
+
+//Active returns true if the plugin has already been activated
+func (p plugin ) Active () bool {
+	return active
+}

frontend/plugins/plugin.go

@@ -4,8 +4,10 @@ import (
 	"log"
 	"sync"
 	"net/http"
+	"database/sql"
 )
 
+//Global variables
 var (
 	pluginMu sync.RWMutex
 	plugins   = make(map[string]Plugin)
@@ -13,21 +15,13 @@ var (
 	universalPlugins [] UniversalHandlerPlugin
 	endpointMappings = make(map[string]func(http.ResponseWriter, *http.Request))
 	mux *http.ServeMux
+	db *sql.DB
 )
 
-//Plugin is an interface defining all plugin exported functions
-type Plugin interface {
-	Activate() //should register endpoints and add database tables etc
-}
-
-//UniversalHandlerPlugin is an interface that extends the Plugin interface, for if a plugin needs to be called on all endpoints
-type UniversalHandlerPlugin interface {
-	Plugin
-	UniversalHandler(http.HandlerFunc) http.HandlerFunc
-}
-
 //SetupPlugins activates plugins and loads endpoints
-func SetupPlugins(m *http.ServeMux, names[] string) {
+func SetupPlugins(m *http.ServeMux, d *sql.DB, names[] string) {
+	mux = m
+	db = d
 	for _, n := range names {
 		if _, exists := plugins[n]; !exists {
 			log.Fatalf("Plugin %s does not exist", n)
@@ -37,7 +31,6 @@ func SetupPlugins(m *http.ServeMux, names[] string) {
 			universalPlugins = append(universalPlugins, p)
 		}
 	}
-	mux = m
 	for key, element := range endpointMappings {
         mux.HandleFunc(key, chainUniversalHandlers(element))
     }

frontend/plugins/root/pages.go

@@ -8,22 +8,17 @@ import (
 	"core-networkmanager/frontend/plugins"
 )
 
+func setup() bool {
+	plugins.RegisterEndpoint("/", homePage)
+	return true
+}
+
 //Page struct to hold per-page data
 type page struct {
 	Location string
 	Name string
 }
 
-type Plugin struct {}
-
-func init() {
-	plugins.RegisterPlugin("root", &Plugin{})
-}
-
-//Activate sets up endpoints and such
-func (p Plugin ) Activate () {
-	plugins.RegisterEndpoint("/", homePage)
-}
 func homePage(w http.ResponseWriter, r *http.Request) {
 	if r.Method == "GET" {
 		t, err := template.ParseFiles("index.gohtml")

frontend/plugins/root/plugin.go

@@ -0,0 +1,32 @@
+package root
+import (
+	"sync"
+	"core-networkmanager/frontend/plugins"
+)
+
+var (
+	mux sync.Mutex
+	active bool
+)
+
+//init registers the plugin as available with Plugin manager
+func init() {
+	plugins.RegisterPlugin("root", &plugin{})
+}
+
+//plugin struct that for the plugin to impliment required and optional interfaces as defined in Plugin package
+type plugin struct {}
+
+//Activate sets up endpoints and databases, and any other initialization 
+func (p plugin ) Activate () {
+	if(!active) {
+		mux.Lock()
+		active = setup()
+		mux.Unlock()
+	}
+}
+
+//Active returns true if the plugin has already been activated
+func (p plugin ) Active () bool {
+	return active
+}

frontend/plugins/types.go

@@ -0,0 +1,17 @@
+package plugins
+
+import (
+	"net/http"
+)
+
+//Plugin is an interface defining all plugin exported functions
+type Plugin interface {
+	Activate() //should register endpoints and add database tables etc
+	Active() bool //should check if plugin has already been activated
+}
+
+//UniversalHandlerPlugin is an interface that extends the Plugin interface, for if a plugin needs to be called on all endpoints
+type UniversalHandlerPlugin interface {
+	Plugin
+	UniversalHandler(http.HandlerFunc) http.HandlerFunc
+}

frontend/server.go

@@ -4,7 +4,6 @@ import (
 	"log"
 	"net/http"
 	"strconv"
-	_ "github.com/lib/pq"
 	"core-networkmanager/frontend/plugins"
 	_ "core-networkmanager/frontend/plugins/root"
 	_ "core-networkmanager/frontend/plugins/assets"
@@ -12,12 +11,14 @@ import (
 
 func main() {
 	initDB()
+	defer db.Close()
 	var port = 8080
 	mux := http.NewServeMux()
 	activePlugins := []string{"root", "assets"}
-	plugins.SetupPlugins(mux, activePlugins)
+	plugins.SetupPlugins(mux, nil, activePlugins)
 	err := http.ListenAndServe(":" + strconv.Itoa(port), mux)
 	if(err != nil) {
 		log.Fatal("ListenAndServe failed with error: ", err)
 	}
+
 }