Prototype with single host server and no admin panel (#2)

Reviewed-on: wrenn/sandbox#2
Co-authored-by: pptx704 <rafeed@omukk.dev>
Co-committed-by: pptx704 <rafeed@omukk.dev>

internal/config/config.go

@@ -0,0 +1,56 @@
+package config
+
+import (
+	"os"
+	"strings"
+
+	"github.com/joho/godotenv"
+)
+
+// Config holds the control plane configuration.
+type Config struct {
+	DatabaseURL   string
+	RedisURL      string
+	ListenAddr    string
+	HostAgentAddr string
+	JWTSecret     string
+
+	OAuthGitHubClientID     string
+	OAuthGitHubClientSecret string
+	OAuthRedirectURL        string
+	CPPublicURL             string
+}
+
+// Load reads configuration from a .env file (if present) and environment variables.
+// Real environment variables take precedence over .env values.
+func Load() Config {
+	// Best-effort load — missing .env file is fine.
+	_ = godotenv.Load()
+
+	cfg := Config{
+		DatabaseURL:   envOrDefault("DATABASE_URL", "postgres://wrenn:wrenn@localhost:5432/wrenn?sslmode=disable"),
+		RedisURL:      envOrDefault("REDIS_URL", "redis://localhost:6379/0"),
+		ListenAddr:    envOrDefault("CP_LISTEN_ADDR", ":8080"),
+		HostAgentAddr: envOrDefault("CP_HOST_AGENT_ADDR", "http://localhost:50051"),
+		JWTSecret:     os.Getenv("JWT_SECRET"),
+
+		OAuthGitHubClientID:     os.Getenv("OAUTH_GITHUB_CLIENT_ID"),
+		OAuthGitHubClientSecret: os.Getenv("OAUTH_GITHUB_CLIENT_SECRET"),
+		OAuthRedirectURL:        envOrDefault("OAUTH_REDIRECT_URL", "https://app.wrenn.dev"),
+		CPPublicURL:             os.Getenv("CP_PUBLIC_URL"),
+	}
+
+	// Ensure the host agent address has a scheme.
+	if !strings.HasPrefix(cfg.HostAgentAddr, "http://") && !strings.HasPrefix(cfg.HostAgentAddr, "https://") {
+		cfg.HostAgentAddr = "http://" + cfg.HostAgentAddr
+	}
+
+	return cfg
+}
+
+func envOrDefault(key, def string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return def
+}