feat: add PawSQL docs examples and image CI

cmd/pawsql/main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"crypto/tls"
+	"errors"
+	"flag"
+	"fmt"
+	"log/slog"
+	"net"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/barkstack/pawsql/internal/config"
+	"github.com/barkstack/pawsql/internal/postgres"
+	"github.com/barkstack/pawsql/internal/router"
+	"github.com/barkstack/pawsql/internal/server"
+)
+
+func main() {
+	logger := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelInfo}))
+	if err := run(os.Args[1:], logger); err != nil {
+		logger.Error("pawsql failed", "error", err)
+		os.Exit(1)
+	}
+}
+
+func run(args []string, logger *slog.Logger) error {
+	validateOnly, configPath, err := parseArguments(args)
+	if err != nil {
+		return err
+	}
+	cfg, err := config.ParseFile(configPath)
+	if err != nil {
+		return err
+	}
+	if err := cfg.Validate(); err != nil {
+		return fmt.Errorf("invalid configuration: %w", err)
+	}
+	certificate, err := tls.LoadX509KeyPair(cfg.TLS.CertFile, cfg.TLS.KeyFile)
+	if err != nil {
+		return fmt.Errorf("load TLS certificate and key: %w", err)
+	}
+	if validateOnly {
+		logger.Info("configuration is valid", "config", configPath)
+		return nil
+	}
+
+	staticResolver, err := router.NewStaticResolver(cfg.Databases)
+	if err != nil {
+		return fmt.Errorf("build route resolver: %w", err)
+	}
+	resolver := postgres.NewResolver(staticResolver, cfg.Databases, postgres.NewProvisioner(logger))
+	routingServer, err := server.New(&tls.Config{Certificates: []tls.Certificate{certificate}}, resolver, logger)
+	if err != nil {
+		return err
+	}
+	listener, err := net.Listen("tcp", cfg.Listen)
+	if err != nil {
+		return fmt.Errorf("listen on %s: %w", cfg.Listen, err)
+	}
+	logger.Info("pawsql listening", "address", listener.Addr().String())
+
+	signals := make(chan os.Signal, 1)
+	signal.Notify(signals, os.Interrupt, syscall.SIGTERM)
+	defer signal.Stop(signals)
+	serveErrors := make(chan error, 1)
+	go func() { serveErrors <- routingServer.Serve(listener) }()
+
+	select {
+	case received := <-signals:
+		logger.Info("shutdown signal received", "signal", received.String())
+		if err := routingServer.Shutdown(); err != nil && !errors.Is(err, net.ErrClosed) {
+			return fmt.Errorf("stop listener: %w", err)
+		}
+		if err := <-serveErrors; err != nil {
+			return err
+		}
+		routingServer.Wait()
+		logger.Info("pawsql shutdown complete")
+		return nil
+	case err := <-serveErrors:
+		return err
+	}
+}
+
+func parseArguments(args []string) (validateOnly bool, configPath string, err error) {
+	if len(args) > 0 && args[0] == "validate" {
+		validateOnly = true
+		args = args[1:]
+	}
+	flags := flag.NewFlagSet("pawsql", flag.ContinueOnError)
+	flags.SetOutput(os.Stderr)
+	configPath = "Barkfile"
+	flags.StringVar(&configPath, "config", configPath, "path to Barkfile")
+	if err := flags.Parse(args); err != nil {
+		return false, "", err
+	}
+	if flags.NArg() != 0 {
+		return false, "", fmt.Errorf("unexpected arguments: %v", flags.Args())
+	}
+	return validateOnly, configPath, nil
+}