feat:#10 added new minimal backend

datamanager/backend/apis/serve.go

@@ -0,0 +1,180 @@
+package apis
+
+import (
+	"context"
+	"crypto/tls"
+	"datamanager/backend/core"
+	"github.com/fatih/color"
+	"github.com/labstack/echo/v5"
+	"github.com/labstack/echo/v5/middleware"
+	"github.com/pocketbase/pocketbase/tools/list"
+	"golang.org/x/crypto/acme"
+	"log"
+	"log/slog"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+)
+
+// ServeConfig defines a configuration struct for apis.Serve().
+type ServeConfig struct {
+	// ShowStartBanner indicates whether to show or hide the server start console message.
+	ShowStartBanner bool
+
+	// HttpAddr is the TCP address to listen for the HTTP server (eg. `127.0.0.1:80`).
+	HttpAddr string
+
+	// HttpsAddr is the TCP address to listen for the HTTPS server (eg. `127.0.0.1:443`).
+	HttpsAddr string
+
+	// Optional domains list to use when issuing the TLS certificate.
+	//
+	// If not set, the host from the bound server address will be used.
+	//
+	// For convenience, for each "non-www" domain a "www" entry and
+	// redirect will be automatically added.
+	CertificateDomains []string
+
+	// AllowedOrigins is an optional list of CORS origins (default to "*").
+	AllowedOrigins []string
+}
+
+func Serve(app core.App, config ServeConfig) (*http.Server, error) {
+	if len(config.AllowedOrigins) == 0 {
+		config.AllowedOrigins = []string{"*"}
+	}
+
+	router, err := InitApi(app)
+	if err != nil {
+		return nil, err
+	}
+
+	// configure cors
+	router.Use(middleware.CORSWithConfig(middleware.CORSConfig{
+		Skipper:      middleware.DefaultSkipper,
+		AllowOrigins: config.AllowedOrigins,
+		AllowMethods: []string{http.MethodGet, http.MethodHead, http.MethodPut, http.MethodPatch, http.MethodPost, http.MethodDelete},
+	}))
+
+	// start http server
+	// ---
+	mainAddr := config.HttpAddr
+	if config.HttpsAddr != "" {
+		mainAddr = config.HttpsAddr
+	}
+
+	var wwwRedirects []string
+
+	// extract the host names for the certificate host policy
+	hostNames := config.CertificateDomains
+	if len(hostNames) == 0 {
+		host, _, _ := net.SplitHostPort(mainAddr)
+		hostNames = append(hostNames, host)
+	}
+	for _, host := range hostNames {
+		if strings.HasPrefix(host, "www.") {
+			continue // explicitly set www host
+		}
+
+		wwwHost := "www." + host
+		if !list.ExistInSlice(wwwHost, hostNames) {
+			hostNames = append(hostNames, wwwHost)
+			wwwRedirects = append(wwwRedirects, wwwHost)
+		}
+	}
+
+	// implicit www->non-www redirect(s)
+	if len(wwwRedirects) > 0 {
+		router.Pre(func(next echo.HandlerFunc) echo.HandlerFunc {
+			return func(c echo.Context) error {
+				host := c.Request().Host
+
+				if strings.HasPrefix(host, "www.") && list.ExistInSlice(host, wwwRedirects) {
+					return c.Redirect(
+						http.StatusTemporaryRedirect,
+						c.Scheme()+"://"+host[4:]+c.Request().RequestURI,
+					)
+				}
+
+				return next(c)
+			}
+		})
+	}
+
+	// base request context used for cancelling long running requests
+	// like the SSE connections
+	baseCtx, cancelBaseCtx := context.WithCancel(context.Background())
+	defer cancelBaseCtx()
+
+	server := &http.Server{
+		TLSConfig: &tls.Config{
+			MinVersion: tls.VersionTLS12,
+			NextProtos: []string{acme.ALPNProto},
+		},
+		ReadTimeout:       10 * time.Minute,
+		ReadHeaderTimeout: 30 * time.Second,
+		// WriteTimeout: 60 * time.Second, // breaks sse!
+		Handler: router,
+		Addr:    mainAddr,
+		BaseContext: func(l net.Listener) context.Context {
+			return baseCtx
+		},
+	}
+
+	if config.ShowStartBanner {
+		schema := "http"
+		addr := server.Addr
+
+		if config.HttpsAddr != "" {
+			schema = "https"
+
+			if len(config.CertificateDomains) > 0 {
+				addr = config.CertificateDomains[0]
+			}
+		}
+
+		date := new(strings.Builder)
+		log.New(date, "", log.LstdFlags).Print()
+
+		bold := color.New(color.Bold).Add(color.FgGreen)
+		_, _ = bold.Printf(
+			"%s Server started at %s\n",
+			strings.TrimSpace(date.String()),
+			color.CyanString("%s://%s", schema, addr),
+		)
+	}
+
+	// WaitGroup to block until server.ShutDown() returns because Serve and similar methods exit immediately.
+	// Note that the WaitGroup would not do anything if the app.OnTerminate() hook isn't triggered.
+	var wg sync.WaitGroup
+
+	// wait for the graceful shutdown to complete before exit
+	defer wg.Wait()
+
+	// ---
+	// @todo consider removing the server return value because it is
+	// not really useful when combined with the blocking serve calls
+	// ---
+
+	// start HTTPS server
+	if config.HttpsAddr != "" {
+		// if httpAddr is set, start an HTTP server to redirect the traffic to the HTTPS version
+		if config.HttpAddr != "" {
+			go func() {
+				err := http.ListenAndServe(config.HttpAddr, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					http.Redirect(w, r, "https://"+r.Host+r.RequestURI, http.StatusMovedPermanently)
+				}))
+				if err != nil {
+					slog.Error("Failed to start HTTP server for redirect: %v", err)
+				}
+			}()
+		}
+
+		return server, server.ListenAndServeTLS("", "")
+	}
+
+	// OR start HTTP server
+	return server, server.ListenAndServe()
+}