Do a large chunk of the move to go

This commit moves a huge chunk of the code to go. The TODO.md document
indicates what is left to be done.

cmd/wdcli/main.go

@@ -0,0 +1,110 @@
+// Command wdcli implement the entry point for the wisski-distillery
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime/debug"
+
+	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
+	"github.com/FAU-CDI/wisski-distillery/cmd"
+	"github.com/FAU-CDI/wisski-distillery/env"
+	"github.com/tkw1536/goprogram/exit"
+	"github.com/tkw1536/goprogram/stream"
+)
+
+var wdcli = wisski_distillery.NewProgram()
+
+func init() {
+	// self commands
+	wdcli.Register(cmd.Config)
+	wdcli.Register(cmd.License)
+
+	// setup commands
+	wdcli.Register(cmd.Bootstrap)
+	wdcli.Register(cmd.SystemUpdate)
+
+	// sql commands
+	wdcli.Register(cmd.Mysql)
+	wdcli.Register(cmd.MakeMysqlAccount)
+
+	// instance setup and teardown
+	wdcli.Register(cmd.Provision)
+	wdcli.Register(cmd.Purge)
+	wdcli.Register(cmd.Reserve)
+	wdcli.Register(cmd.Rebuild)
+
+	// instance management
+	wdcli.Register(cmd.Ls)
+	wdcli.Register(cmd.Info)
+
+	// instance tasks
+	wdcli.Register(cmd.Shell)
+	wdcli.Register(cmd.BlindUpdate)
+	wdcli.Register(cmd.Cron)
+	wdcli.Register(cmd.UpdatePrefixConfig) // TODO: Move into post-instance configuration
+
+	// backup & cron
+	// wdcli.Register(cmd.BackupInstance)
+	// wdcli.Register(cmd.BackupAll)
+}
+
+// an error when no arguments are provided.
+var errNoArgumentsProvided = exit.Error{
+	ExitCode: exit.ExitGeneralArguments,
+	Message:  "Need at least one argument. Use `wdcli license` to view licensing information. ",
+}
+
+func main() {
+	// recover from calls to panic(), and exit the program appropriatly.
+	// This has to be in the main() function because any of the library functions might be broken.
+	// For this reason, as few ggman functions as possible are used here; just stuff from the top-level ggman package.
+	defer func() {
+		if err := recover(); err != nil {
+			fmt.Fprintf(os.Stderr, fatalPanicMessage, err)
+			debug.PrintStack()
+			exit.ExitPanic.Return()
+		}
+	}()
+
+	streams := stream.FromEnv()
+
+	// when there are no arguments then parsing argument *will* fail
+	//
+	// we don't need to even bother with the rest of the program
+	// just immediatly return a custom error message.
+	if len(os.Args) == 1 {
+		streams.Die(errNoArgumentsProvided)
+		errNoArgumentsProvided.Return()
+		return
+	}
+
+	// creat a new set of parameters
+	// and then use them to execute the main command
+	err := func() error {
+		params, err := env.ParamsFromEnv()
+		if err != nil {
+			return streams.Die(err)
+		}
+
+		return wdcli.Main(streams, params, os.Args[1:])
+	}()
+
+	// return the error to the user
+
+	exit.AsError(err).Return()
+}
+
+const fatalPanicMessage = `Fatal Error: Panic
+
+The wdcli program panicked and had to abort execution. This is usually
+indicative of a bug. If this occurs repeatedly you might want to consider
+filing an issue in the issue tracker at:
+
+https://github.com/FAU-CDI/wisski-distillery/issues
+
+Below is debug information that might help the developers track down what
+happened.
+
+panic: %v
+`