main() is one call into internal/cli (closes #160)

cmd/netwatch-server/main.go parsed the command line, ran the check-cidr
and prepare-data-dir subcommands and built the fx application itself;
the Go style guide puts all of that in internal/ or pkg/. The new
package internal/cli does it, with the same arguments, messages and
exit codes. main() is now os.Exit(cli.Main(os.Stderr, Appname, Version,
os.Args[1:], cli.RunServer)): Main takes the writer for errors and the
function that runs the server, so its tests give it a buffer and a
function that fails them. Appname and Version stay in main, where the
build sets Version. The function behind prepare-data-dir also takes the
volume and the user's name, so its own tests give it a temporary
directory and the user they run as.

Model: opus-5-5

cmd/netwatch-server/main.go

@@ -1,22 +1,11 @@
-// Package main is the entry point for netwatch-server.
+// Package main is the entry point for netwatch-server; package cli
+// does the work.
 package main
 
 import (
-	"fmt"
 	"os"
-	"os/user"
 
-	"sneak.berlin/go/netwatch/internal/config"
-	"sneak.berlin/go/netwatch/internal/globals"
-	"sneak.berlin/go/netwatch/internal/handlers"
-	"sneak.berlin/go/netwatch/internal/healthcheck"
-	"sneak.berlin/go/netwatch/internal/logger"
-	"sneak.berlin/go/netwatch/internal/middleware"
-	"sneak.berlin/go/netwatch/internal/reportbuf"
-	"sneak.berlin/go/netwatch/internal/server"
-
-	"go.uber.org/fx"
-	"go.uber.org/fx/fxevent"
+	"sneak.berlin/go/netwatch/internal/cli"
 )
 
 //nolint:gochecknoglobals // set via ldflags at build time
@@ -26,64 +15,5 @@ var (
 )
 
 func main() {
-	// "netwatch-server check-cidr CIDR" exits 1, with the error, if
-	// this server would refuse CIDR in its TRUSTED_PROXIES.
-	// bin/entrypoint.sh runs it on each entry it gives nginx.
-	if len(os.Args) == 3 && os.Args[1] == "check-cidr" {
-		_, err := middleware.ParseTrustedProxies(os.Args[2:])
-		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
-		}
-
-		return
-	}
-
-	// "netwatch-server prepare-data-dir DATA_DIR" gets DATA_DIR ready
-	// for the netwatch user, or exits 1 with the error; see
-	// reportbuf.PrepareDataDir. bin/entrypoint.sh runs it as root
-	// before it starts this server as that user.
-	if len(os.Args) == 3 && os.Args[1] == "prepare-data-dir" {
-		netwatch, err := user.Lookup("netwatch")
-		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
-		}
-
-		err = reportbuf.PrepareDataDir("/data", os.Args[2], netwatch)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "DATA_DIR '%s': %v\n", os.Args[2], err)
-			os.Exit(1)
-		}
-
-		return
-	}
-
-	globals.Appname = Appname
-	globals.Version = Version
-
-	fx.New(
-		// fx logs each step of starting and stopping through the
-		// server's own logger, so off a terminal those lines are
-		// JSON like every other line.
-		fx.WithLogger(func(log *logger.Logger) fxevent.Logger {
-			return &fxevent.SlogLogger{Logger: log.Get()}
-		}),
-		fx.Provide(
-			config.New,
-			globals.New,
-			handlers.New,
-			healthcheck.New,
-			logger.New,
-			middleware.New,
-			reportbuf.New,
-			server.New,
-		),
-		fx.Invoke(
-			// First, so the name and version are logged even when
-			// a setting stops the start.
-			func(log *logger.Logger) { log.Identify() },
-			func(*server.Server) {},
-		),
-	).Run()
+	os.Exit(cli.Main(os.Stderr, Appname, Version, os.Args[1:], cli.RunServer))
 }