From d0b59cb4116077890768ff8b693ef99cf45f28a8 Mon Sep 17 00:00:00 2001
From: Pierre-Olivier Mercier <nemunaire@nemunai.re>
Date: Sun, 2 May 2021 22:49:51 +0200
Subject: [PATCH] Add some config through flag/env

---
 app.go           | 13 +++++++++----
 config/cli.go    | 45 +++++++++++++++++++++++++++++++++++++++++++++
 config/config.go | 28 ++++++++++++++++++++++++++++
 config/env.go    | 21 +++++++++++++++++++++
 main.go          |  9 ++++++++-
 ui/routes.go     | 10 +++++++++-
 6 files changed, 120 insertions(+), 6 deletions(-)
 create mode 100644 config/cli.go
 create mode 100644 config/config.go
 create mode 100644 config/env.go

diff --git a/app.go b/app.go
index 7f95e8f..bdab283 100644
--- a/app.go
+++ b/app.go
@@ -13,6 +13,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"nhooyr.io/websocket"
 
+	"github.com/nemunaire/minifaas/config"
 	"github.com/nemunaire/minifaas/engine/docker"
 	"github.com/nemunaire/minifaas/ui"
 )
@@ -20,17 +21,20 @@ import (
 type App struct {
 	router *gin.Engine
 	srv    *http.Server
+	cfg    *config.Config
 }
 
-func NewApp() App {
+func NewApp(cfg *config.Config) App {
 	//Check rights on artifacts directory
 	os.MkdirAll("./artifacts", os.ModePerm)
 
-	//gin.SetMode(gin.ReleaseMode)
+	if !cfg.Dev {
+		gin.SetMode(gin.ReleaseMode)
+	}
 	gin.ForceConsoleColor()
 	router := gin.Default()
 
-	ui.DeclareRoutes(router)
+	ui.DeclareRoutes(router, cfg)
 
 	artifacts := http.Dir("./artifacts")
 	router.GET("/artifacts/*path", func(c *gin.Context) {
@@ -123,6 +127,7 @@ func NewApp() App {
 
 	app := App{
 		router: router,
+		cfg:    cfg,
 	}
 
 	return app
@@ -130,7 +135,7 @@ func NewApp() App {
 
 func (app *App) Start() {
 	app.srv = &http.Server{
-		Addr:    ":8082",
+		Addr:    app.cfg.Bind,
 		Handler: app.router,
 	}
 
diff --git a/config/cli.go b/config/cli.go
new file mode 100644
index 0000000..2bacfb1
--- /dev/null
+++ b/config/cli.go
@@ -0,0 +1,45 @@
+package config
+
+import (
+	"flag"
+)
+
+// declareFlags registers flags for the structure Options.
+func (c *Config) declareFlags() {
+	flag.BoolVar(&c.Dev, "dev", c.Dev, "Use ui directory instead of embedded assets")
+	flag.StringVar(&c.Bind, "bind", c.Bind, "Bind port/socket")
+	flag.StringVar(&c.ExternalURL, "externalurl", c.ExternalURL, "Begining of the URL, before the base, that should be used eg. in mails")
+
+	// Others flags are declared in some other files when they need specials configurations
+}
+
+func Consolidated() (cfg *Config, err error) {
+	// Define defaults options
+	cfg = &Config{
+		Bind:        ":8082",
+		ExternalURL: "http://localhost:8082",
+	}
+
+	cfg.declareFlags()
+
+	// Then, overwrite that by what is present in the environment
+	err = cfg.FromEnv()
+	if err != nil {
+		return
+	}
+
+	// Finaly, command line takes precedence
+	err = cfg.parseCLI()
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+// parseCLI parse the flags and treats extra args as configuration filename.
+func (c *Config) parseCLI() error {
+	flag.Parse()
+
+	return nil
+}
diff --git a/config/config.go b/config/config.go
new file mode 100644
index 0000000..579e835
--- /dev/null
+++ b/config/config.go
@@ -0,0 +1,28 @@
+package config
+
+import (
+	"flag"
+	"strings"
+)
+
+type Config struct {
+	Dev         bool
+	Bind        string
+	ExternalURL string
+}
+
+// parseLine treats a config line and place the read value in the variable
+// declared to the corresponding flag.
+func (c *Config) parseLine(line string) (err error) {
+	fields := strings.SplitN(line, "=", 2)
+	orig_key := strings.TrimSpace(fields[0])
+	value := strings.TrimSpace(fields[1])
+
+	key := strings.TrimPrefix(orig_key, "MINIFAAS_")
+	key = strings.Replace(key, "_", "-", -1)
+	key = strings.ToLower(key)
+
+	err = flag.Set(key, value)
+
+	return
+}
diff --git a/config/env.go b/config/env.go
new file mode 100644
index 0000000..d54bc3d
--- /dev/null
+++ b/config/env.go
@@ -0,0 +1,21 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+// FromEnv analyzes all the environment variables to find each one
+// starting by MINIFAAS_
+func (c *Config) FromEnv() error {
+	for _, line := range os.Environ() {
+		if strings.HasPrefix(line, "MINIFAAS_") {
+			err := c.parseLine(line)
+			if err != nil {
+				return fmt.Errorf("error in environment (%q): %w", line, err)
+			}
+		}
+	}
+	return nil
+}
diff --git a/main.go b/main.go
index fe4ef9c..6e114fb 100644
--- a/main.go
+++ b/main.go
@@ -5,10 +5,17 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+
+	"github.com/nemunaire/minifaas/config"
 )
 
 func main() {
-	a := NewApp()
+	cfg, err := config.Consolidated()
+	if err != nil {
+		log.Fatal("Unable to read configuration:", err)
+	}
+
+	a := NewApp(cfg)
 	go a.Start()
 
 	quit := make(chan os.Signal)
diff --git a/ui/routes.go b/ui/routes.go
index 4bf01b8..8646934 100644
--- a/ui/routes.go
+++ b/ui/routes.go
@@ -1,10 +1,18 @@
 package ui
 
 import (
+	"net/http"
+
 	"github.com/gin-gonic/gin"
+
+	"github.com/nemunaire/minifaas/config"
 )
 
-func DeclareRoutes(router *gin.Engine) {
+func DeclareRoutes(router *gin.Engine, cfg *config.Config) {
+	if cfg.Dev {
+		Assets = http.Dir("./ui")
+	}
+
 	router.GET("/", serveOrReverse("/"))
 	router.GET("/favicon.ico", serveOrReverse("/favicon.ico"))
 	router.GET("/manifest.json", serveOrReverse("/manifest.json"))