Rename binary to litestream; add replicate command

cmd/litestream/replicate.go

@@ -0,0 +1,148 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"os/signal"
+
+	"github.com/benbjohnson/litestream"
+)
+
+type ReplicateCommand struct {
+	ConfigPath string
+	Config     Config
+
+	// List of managed databases specified in the config.
+	DBs []*litestream.DB
+}
+
+func NewReplicateCommand() *ReplicateCommand {
+	return &ReplicateCommand{}
+}
+
+// Run loads all databases specified in the configuration.
+func (c *ReplicateCommand) Run(ctx context.Context, args []string) (err error) {
+	fs := flag.NewFlagSet("litestream-replicate", flag.ContinueOnError)
+	registerConfigFlag(fs, &c.ConfigPath)
+	fs.Usage = c.Usage
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+
+	// Load configuration.
+	if c.ConfigPath == "" {
+		return errors.New("-config required")
+	}
+	config, err := ReadConfigFile(c.ConfigPath)
+	if err != nil {
+		return err
+	}
+
+	// Setup signal handler.
+	ctx, cancel := context.WithCancel(context.Background())
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, os.Interrupt)
+	go func() { <-ch; cancel() }()
+
+	// Display version information.
+	fmt.Printf("litestream %s\n", Version)
+
+	if len(config.DBs) == 0 {
+		return errors.New("configuration must specify at least one database")
+	}
+
+	for _, dbc := range config.DBs {
+		if err := c.openDB(dbc); err != nil {
+			return err
+		}
+	}
+
+	// Notify user that initialization is done.
+	fmt.Printf("Initialized with %d databases.\n", len(c.DBs))
+
+	// Wait for signal to stop program.
+	<-ctx.Done()
+	signal.Reset()
+
+	// Gracefully close
+	if err := c.Close(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	return nil
+}
+
+// openDB instantiates and initializes a DB based on a configuration.
+func (c *ReplicateCommand) openDB(config *DBConfig) error {
+	// Initialize database with given path.
+	db := litestream.NewDB(config.Path)
+
+	// Instantiate and attach replicators.
+	for _, rconfig := range config.Replicas {
+		r, err := c.createReplicator(db, rconfig)
+		if err != nil {
+			return err
+		}
+		db.Replicators = append(db.Replicators, r)
+	}
+
+	// Open database & attach to program.
+	if err := db.Open(); err != nil {
+		return err
+	}
+	c.DBs = append(c.DBs, db)
+
+	return nil
+}
+
+// createReplicator instantiates a replicator for a DB based on a config.
+func (c *ReplicateCommand) createReplicator(db *litestream.DB, config *ReplicaConfig) (litestream.Replicator, error) {
+	switch config.Type {
+	case "", "file":
+		return c.createFileReplicator(db, config)
+	default:
+		return nil, fmt.Errorf("unknown replicator type in config: %q", config.Type)
+	}
+}
+
+// createFileReplicator returns a new instance of FileReplicator build from config.
+func (c *ReplicateCommand) createFileReplicator(db *litestream.DB, config *ReplicaConfig) (*litestream.FileReplicator, error) {
+	if config.Path == "" {
+		return nil, fmt.Errorf("file replicator path require for db %q", db.Path())
+	}
+	return litestream.NewFileReplicator(db, config.Name, config.Path), nil
+}
+
+// Close closes all open databases.
+func (c *ReplicateCommand) Close() (err error) {
+	for _, db := range c.DBs {
+		if e := db.SoftClose(); e != nil {
+			fmt.Printf("error closing db: path=%s err=%s\n", db.Path(), e)
+			if err == nil {
+				err = e
+			}
+		}
+	}
+	return err
+}
+
+func (c *ReplicateCommand) Usage() {
+	fmt.Println(`
+The replicate command starts a server to monitor & replicate databases 
+specified in your configuration file.
+
+Usage:
+
+	litestream replicate [arguments]
+
+Arguments:
+
+	-config PATH
+	    Specifies the configuration file. Defaults to ~/litestream.yml
+
+`[1:])
+}