Prevent user from specifying replica URL & config flag

Previously, if a replica URL was specified then the `-config` flag
was silently ignored. This commit changes this behavior so that
specifying both the URL & config flag will now return an error.

cmd/litestream/databases.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"os"
@@ -15,9 +14,8 @@ type DatabasesCommand struct{}
 
 // Run executes the command.
 func (c *DatabasesCommand) Run(ctx context.Context, args []string) (err error) {
-	var configPath string
 	fs := flag.NewFlagSet("litestream-databases", flag.ContinueOnError)
-	registerConfigFlag(fs, &configPath)
+	configPath := registerConfigFlag(fs)
 	fs.Usage = c.Usage
 	if err := fs.Parse(args); err != nil {
 		return err
@@ -26,10 +24,10 @@ func (c *DatabasesCommand) Run(ctx context.Context, args []string) (err error) {
 	}
 
 	// Load configuration.
-	if configPath == "" {
-		return errors.New("-config required")
+	if *configPath == "" {
+		*configPath = DefaultConfigPath()
 	}
-	config, err := ReadConfigFile(configPath)
+	config, err := ReadConfigFile(*configPath)
 	if err != nil {
 		return err
 	}

cmd/litestream/generations.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"log"
@@ -18,9 +17,8 @@ type GenerationsCommand struct{}
 
 // Run executes the command.
 func (c *GenerationsCommand) Run(ctx context.Context, args []string) (err error) {
-	var configPath string
 	fs := flag.NewFlagSet("litestream-generations", flag.ContinueOnError)
-	registerConfigFlag(fs, &configPath)
+	configPath := registerConfigFlag(fs)
 	replicaName := fs.String("replica", "", "replica name")
 	fs.Usage = c.Usage
 	if err := fs.Parse(args); err != nil {
@@ -35,12 +33,19 @@ func (c *GenerationsCommand) Run(ctx context.Context, args []string) (err error)
 	var r litestream.Replica
 	updatedAt := time.Now()
 	if isURL(fs.Arg(0)) {
+		if *configPath != "" {
+			return fmt.Errorf("cannot specify a replica URL and the -config flag")
+		}
 		if r, err = NewReplicaFromConfig(&ReplicaConfig{URL: fs.Arg(0)}, nil); err != nil {
 			return err
 		}
-	} else if configPath != "" {
+	} else {
+		if *configPath == "" {
+			*configPath = DefaultConfigPath()
+		}
+
 		// Load configuration.
-		config, err := ReadConfigFile(configPath)
+		config, err := ReadConfigFile(*configPath)
 		if err != nil {
 			return err
 		}
@@ -65,8 +70,6 @@ func (c *GenerationsCommand) Run(ctx context.Context, args []string) (err error)
 		if updatedAt, err = db.UpdatedAt(); err != nil {
 			return err
 		}
-	} else {
-		return errors.New("config path or replica URL required")
 	}
 
 	var replicas []litestream.Replica

cmd/litestream/main.go

@@ -429,8 +429,8 @@ func DefaultConfigPath() string {
 	return defaultConfigPath
 }
 
-func registerConfigFlag(fs *flag.FlagSet, p *string) {
-	fs.StringVar(p, "config", DefaultConfigPath(), "config path")
+func registerConfigFlag(fs *flag.FlagSet) *string {
+	return fs.String("config", "", "config path")
 }
 
 // expand returns an absolute path for s.

cmd/litestream/replicate.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"log"
@@ -19,8 +18,7 @@ import (
 
 // ReplicateCommand represents a command that continuously replicates SQLite databases.
 type ReplicateCommand struct {
-	ConfigPath string
-	Config     Config
+	Config Config
 
 	// List of managed databases specified in the config.
 	DBs []*litestream.DB
@@ -34,7 +32,7 @@ func NewReplicateCommand() *ReplicateCommand {
 func (c *ReplicateCommand) ParseFlags(ctx context.Context, args []string) (err error) {
 	fs := flag.NewFlagSet("litestream-replicate", flag.ContinueOnError)
 	tracePath := fs.String("trace", "", "trace path")
-	registerConfigFlag(fs, &c.ConfigPath)
+	configPath := registerConfigFlag(fs)
 	fs.Usage = c.Usage
 	if err := fs.Parse(args); err != nil {
 		return err
@@ -44,6 +42,10 @@ func (c *ReplicateCommand) ParseFlags(ctx context.Context, args []string) (err e
 	if fs.NArg() == 1 {
 		return fmt.Errorf("must specify at least one replica URL for %s", fs.Arg(0))
 	} else if fs.NArg() > 1 {
+		if *configPath != "" {
+			return fmt.Errorf("cannot specify a replica URL and the -config flag")
+		}
+
 		dbConfig := &DBConfig{Path: fs.Arg(0)}
 		for _, u := range fs.Args()[1:] {
 			dbConfig.Replicas = append(dbConfig.Replicas, &ReplicaConfig{
@@ -52,12 +54,13 @@ func (c *ReplicateCommand) ParseFlags(ctx context.Context, args []string) (err e
 			})
 		}
 		c.Config.DBs = []*DBConfig{dbConfig}
-	} else if c.ConfigPath != "" {
-		if c.Config, err = ReadConfigFile(c.ConfigPath); err != nil {
+	} else {
+		if *configPath == "" {
+			*configPath = DefaultConfigPath()
+		}
+		if c.Config, err = ReadConfigFile(*configPath); err != nil {
 			return err
 		}
-	} else {
-		return errors.New("-config flag or database/replica arguments required")
 	}
 
 	// Enable trace logging.

cmd/litestream/restore.go

@@ -17,12 +17,11 @@ type RestoreCommand struct{}
 
 // Run executes the command.
 func (c *RestoreCommand) Run(ctx context.Context, args []string) (err error) {
-	var configPath string
 	opt := litestream.NewRestoreOptions()
 	opt.Verbose = true
 
 	fs := flag.NewFlagSet("litestream-restore", flag.ContinueOnError)
-	registerConfigFlag(fs, &configPath)
+	configPath := registerConfigFlag(fs)
 	fs.StringVar(&opt.OutputPath, "o", "", "output path")
 	fs.StringVar(&opt.ReplicaName, "replica", "", "replica name")
 	fs.StringVar(&opt.Generation, "generation", "", "generation name")
@@ -59,15 +58,19 @@ func (c *RestoreCommand) Run(ctx context.Context, args []string) (err error) {
 	// Determine replica & generation to restore from.
 	var r litestream.Replica
 	if isURL(fs.Arg(0)) {
+		if *configPath != "" {
+			return fmt.Errorf("cannot specify a replica URL and the -config flag")
+		}
 		if r, err = c.loadFromURL(ctx, fs.Arg(0), &opt); err != nil {
 			return err
 		}
-	} else if configPath != "" {
-		if r, err = c.loadFromConfig(ctx, fs.Arg(0), configPath, &opt); err != nil {
+	} else {
+		if *configPath == "" {
+			*configPath = DefaultConfigPath()
+		}
+		if r, err = c.loadFromConfig(ctx, fs.Arg(0), *configPath, &opt); err != nil {
 			return err
 		}
-	} else {
-		return errors.New("config path or replica URL required")
 	}
 
 	// Return an error if no matching targets found.

cmd/litestream/snapshots.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"os"
@@ -17,9 +16,8 @@ type SnapshotsCommand struct{}
 
 // Run executes the command.
 func (c *SnapshotsCommand) Run(ctx context.Context, args []string) (err error) {
-	var configPath string
 	fs := flag.NewFlagSet("litestream-snapshots", flag.ContinueOnError)
-	registerConfigFlag(fs, &configPath)
+	configPath := registerConfigFlag(fs)
 	replicaName := fs.String("replica", "", "replica name")
 	fs.Usage = c.Usage
 	if err := fs.Parse(args); err != nil {
@@ -33,12 +31,19 @@ func (c *SnapshotsCommand) Run(ctx context.Context, args []string) (err error) {
 	var db *litestream.DB
 	var r litestream.Replica
 	if isURL(fs.Arg(0)) {
+		if *configPath != "" {
+			return fmt.Errorf("cannot specify a replica URL and the -config flag")
+		}
 		if r, err = NewReplicaFromConfig(&ReplicaConfig{URL: fs.Arg(0)}, nil); err != nil {
 			return err
 		}
-	} else if configPath != "" {
+	} else {
+		if *configPath == "" {
+			*configPath = DefaultConfigPath()
+		}
+
 		// Load configuration.
-		config, err := ReadConfigFile(configPath)
+		config, err := ReadConfigFile(*configPath)
 		if err != nil {
 			return err
 		}
@@ -58,8 +63,6 @@ func (c *SnapshotsCommand) Run(ctx context.Context, args []string) (err error) {
 				return fmt.Errorf("replica %q not found for database %q", *replicaName, db.Path())
 			}
 		}
-	} else {
-		return errors.New("config path or replica URL required")
 	}
 
 	// Find snapshots by db or replica.

cmd/litestream/wal.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"os"
@@ -17,9 +16,8 @@ type WALCommand struct{}
 
 // Run executes the command.
 func (c *WALCommand) Run(ctx context.Context, args []string) (err error) {
-	var configPath string
 	fs := flag.NewFlagSet("litestream-wal", flag.ContinueOnError)
-	registerConfigFlag(fs, &configPath)
+	configPath := registerConfigFlag(fs)
 	replicaName := fs.String("replica", "", "replica name")
 	generation := fs.String("generation", "", "generation name")
 	fs.Usage = c.Usage
@@ -34,12 +32,19 @@ func (c *WALCommand) Run(ctx context.Context, args []string) (err error) {
 	var db *litestream.DB
 	var r litestream.Replica
 	if isURL(fs.Arg(0)) {
+		if *configPath != "" {
+			return fmt.Errorf("cannot specify a replica URL and the -config flag")
+		}
 		if r, err = NewReplicaFromConfig(&ReplicaConfig{URL: fs.Arg(0)}, nil); err != nil {
 			return err
 		}
-	} else if configPath != "" {
+	} else {
+		if *configPath == "" {
+			*configPath = DefaultConfigPath()
+		}
+
 		// Load configuration.
-		config, err := ReadConfigFile(configPath)
+		config, err := ReadConfigFile(*configPath)
 		if err != nil {
 			return err
 		}
@@ -59,8 +64,6 @@ func (c *WALCommand) Run(ctx context.Context, args []string) (err error) {
 				return fmt.Errorf("replica %q not found for database %q", *replicaName, db.Path())
 			}
 		}
-	} else {
-		return errors.New("config path or replica URL required")
 	}
 
 	// Find WAL files by db or replica.