initial commit

cmd/go-bananas/main.go

@@ -0,0 +1,95 @@
+// Command go-bananas is the theme service: an administrative UI for authoring
+// design-token themes, and a runtime API that serves those themes to any
+// application at run time.
+//
+// It reads its entire configuration from the environment so that the Helm chart
+// is the single source of truth for how a deployment is configured.
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/urpi/go-bananas/internal/app"
+)
+
+func main() {
+	os.Exit(run(os.Args[1:]))
+}
+
+// run dispatches on the subcommand and returns the process exit status.
+//
+// The subcommand is checked before the signal handler is installed: a backup is a
+// short batch job that should exit on its own, and a context cancelled by an
+// interrupt would make a snapshot look like it failed when it was in fact told to
+// stop.
+func run(args []string) int {
+	// The server is the default, so an invocation with no arguments, or one whose
+	// first argument is not a known subcommand, starts it.
+	if len(args) > 0 {
+		switch args[0] {
+		case "backup":
+			if err := app.RunBackup(context.Background(), args[1:]); err != nil {
+				fmt.Fprintf(os.Stderr, "Go Bananas!! backup: %v\n", err)
+				return 1
+			}
+			return 0
+		case "version":
+			fmt.Printf("Go Bananas!! %s\n", app.Version)
+			return 0
+		case "help", "-h", "--help":
+			usage(os.Stdout)
+			return 0
+		}
+	}
+
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+
+	if err := app.Run(ctx); err != nil {
+		// Configuration and wiring failures are the expected failure mode at
+		// start-up, so they are reported plainly on stderr with no log decoration.
+		fmt.Fprintf(os.Stderr, "Go Bananas!!: %v\n", err)
+		return exitCodeFor(err)
+	}
+	return 0
+}
+
+// usage prints the top-level help.
+func usage(w io.Writer) {
+	fmt.Fprint(w, `usage: go-bananas [command]
+
+Runs the theme service: an administrative UI for authoring design-token themes and
+a runtime API that serves them to any application at run time.
+
+With no command, the HTTP server starts. Configuration comes entirely from the
+environment; see docs/deployment.md.
+
+Commands:
+  backup    Write a consistent snapshot of the database and exit
+  version   Print the build version
+  help      Print this message
+
+Examples:
+  go-bananas
+  go-bananas backup --to /srv/data/snapshots/go-bananas.db
+`)
+}
+
+// exitCodeFor maps an error onto a process exit status.
+//
+//	1  configuration or wiring failure
+//	2  the context was cancelled before the server started
+func exitCodeFor(err error) int {
+	switch {
+	case errors.Is(err, context.Canceled):
+		return 2
+	default:
+		return 1
+	}
+}