From 68f135fb7b0562ec03d52ec0704bbdf57249829a Mon Sep 17 00:00:00 2001
From: Stefan Friese <stefan.friese@t-systems.com>
Date: Fri, 17 Jan 2025 09:04:20 +0000
Subject: [PATCH] changed hardcoded database configuration to environment
 variables. Other configuration can also be added to the configuration struct
 for further usage inside the app. Added an environment file to source for
 development and usage outside the cluster.

---
 .env       |  7 +++++++
 .gitignore |  1 +
 go.mod     |  1 +
 go.sum     |  2 ++
 main.go    | 40 ++++++++++++++++++++++++++++------------
 5 files changed, 39 insertions(+), 12 deletions(-)
 create mode 100644 .env

diff --git a/.env b/.env
new file mode 100644
index 0000000..29b888b
--- /dev/null
+++ b/.env
@@ -0,0 +1,7 @@
+#!/usr/bin/env sh
+
+export DB_HOST="127.0.0.1"
+export DB_PORT=3306
+export DB_USERNAME="mysql"
+export DB_PASSWORD="mysql"
+export DB_NAME="gomatic"
diff --git a/.gitignore b/.gitignore
index cb77ab3..ee46fee 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,5 @@ gontrol
 bin/*
 build/
 build/*
+pkg/*
 agents/agents
diff --git a/go.mod b/go.mod
index b16a01d..4798552 100644
--- a/go.mod
+++ b/go.mod
@@ -5,6 +5,7 @@ go 1.23.4
 require (
 	github.com/go-sql-driver/mysql v1.8.1
 	github.com/gorilla/websocket v1.5.3
+	github.com/kelseyhightower/envconfig v1.4.0
 )
 
 require filippo.io/edwards25519 v1.1.0 // indirect
diff --git a/go.sum b/go.sum
index 5142118..82db585 100644
--- a/go.sum
+++ b/go.sum
@@ -4,3 +4,5 @@ github.com/go-sql-driver/mysql v1.8.1 h1:LedoTUt/eveggdHS9qUFC1EFSa8bU2+1pZjSRpv
 github.com/go-sql-driver/mysql v1.8.1/go.mod h1:wEBSXgmK//2ZFJyE+qWnIsVGmvmEKlqwuVSjsCm7DZg=
 github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/kelseyhightower/envconfig v1.4.0 h1:Im6hONhd3pLkfDFsbRgu68RDNkGF1r3dvMUtDTo2cv8=
+github.com/kelseyhightower/envconfig v1.4.0/go.mod h1:cccZRl6mQpaq41TPp5QxidR+Sa3axMbJDNb//FQX6Gg=
diff --git a/main.go b/main.go
index ce47808..a90fe1c 100644
--- a/main.go
+++ b/main.go
@@ -21,26 +21,39 @@ import (
 	"syscall"
 
 	"gontrol/src/randomname"
-	websocketserver "gontrol/src/server/websocket"
 	api "gontrol/src/server/api"
+	websocketserver "gontrol/src/server/websocket"
 
 	"os/signal"
 
 	_ "github.com/go-sql-driver/mysql"
-	// "github.com/gorilla/websocket"
+	"github.com/kelseyhightower/envconfig"
 )
 
 var tmpl *template.Template
 var db 	 *sql.DB
 
-const (
-	keyServerAddr = "serverAddr"
-	dbHost = "127.0.0.1"
-	dbUser = "mysql"
-	dbPort = 3306
-	dbPassword = "mysql"
-	dbName = "gomatic"
-)
+type Config struct {
+	Database struct {
+		Username string `envconfig:"DB_USERNAME"`
+		Password string `envconfig:"DB_PASSWORD"`
+		Port     int16  `envconfig:"DB_PORT"`
+		Name     string `envconfig:"DB_NAME"`
+		Host     string `envconfig:"DB_HOST"`
+	}
+}
+
+func readEnv(cfg *Config) {
+	err := envconfig.Process("", cfg)
+	if err != nil {
+		processError(err)
+	}
+}
+
+func processError(err error) {
+	fmt.Println(err)
+	os.Exit(2)
+}
 
 type Agent struct {
 	AgentID        int    `json:"agentId"`
@@ -55,7 +68,7 @@ func init() {
 	tmpl, _ = template.ParseGlob("templates/*.html")
 }
 
-func initDB () {
+func initDB (dbUser string, dbPassword string, dbHost string, dbPort int16, dbName string ) {
 	var err  error
 	dbOpen := fmt.Sprintf("%s:%s@(%s:%d)/%s?parseTime=true", dbUser,dbPassword, dbHost, dbPort, dbName)
 	db, err = sql.Open("mysql", dbOpen)
@@ -140,6 +153,9 @@ func getAgentNames(w http.ResponseWriter, r *http.Request) {
 
 func main() {
 
+	var cfg Config
+	readEnv(&cfg)
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
@@ -161,7 +177,7 @@ func main() {
 	webMux.HandleFunc("/agentNames", getAgentNames)
 	webMux.HandleFunc("/agents/{agentId}", agentsHandler)
 
-	initDB()
+	initDB (cfg.Database.Username, cfg.Database.Password, cfg.Database.Host, cfg.Database.Port, cfg.Database.Name)
 	defer db.Close()
 	name := randomname.GenerateRandomName()
 	fmt.Println(name)