Add --migrate command

This runs database migrations and obviates the need for manually running
changes.

Ref T509

app.go

@@ -36,6 +36,7 @@ import (
 	"github.com/writeas/web-core/log"
 	"github.com/writeas/writefreely/author"
 	"github.com/writeas/writefreely/config"
+	"github.com/writeas/writefreely/migrations"
 	"github.com/writeas/writefreely/page"
 )
 
@@ -193,6 +194,7 @@ func Serve() {
 	doConfig := flag.Bool("config", false, "Run the configuration process")
 	genKeys := flag.Bool("gen-keys", false, "Generate encryption and authentication keys")
 	createSchema := flag.Bool("init-db", false, "Initialize app database")
+	migrate := flag.Bool("migrate", false, "Migrate the database")
 	createAdmin := flag.String("create-admin", "", "Create an admin with the given username:password")
 	createUser := flag.String("create-user", "", "Create a regular user with the given username:password")
 	resetPassUser := flag.String("reset-pass", "", "Reset the given user's password")
@@ -312,6 +314,18 @@ func Serve() {
 		}
 		log.Info("Success.")
 		os.Exit(0)
+	} else if *migrate {
+		loadConfig(app)
+		connectToDatabase(app)
+		defer shutdown(app)
+
+		err := migrations.Migrate(migrations.NewDatastore(app.db.DB, app.db.driverName))
+		if err != nil {
+			log.Error("migrate: %s", err)
+			os.Exit(1)
+		}
+
+		os.Exit(0)
 	}
 
 	log.Info("Initializing...")

migrations/drivers.go

@@ -0,0 +1,66 @@
+/*
+ * Copyright © 2019 A Bunch Tell LLC.
+ *
+ * This file is part of WriteFreely.
+ *
+ * WriteFreely is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, included
+ * in the LICENSE file in this source code package.
+ */
+
+package migrations
+
+import (
+	"fmt"
+)
+
+// TODO: use now() from writefreely pkg
+func (db *datastore) now() string {
+	if db.driverName == driverSQLite {
+		return "strftime('%Y-%m-%d %H:%M:%S','now')"
+	}
+	return "NOW()"
+}
+
+func (db *datastore) typeInt() string {
+	if db.driverName == driverSQLite {
+		return "INTEGER"
+	}
+	return "INT"
+}
+
+func (db *datastore) typeSmallInt() string {
+	if db.driverName == driverSQLite {
+		return "INTEGER"
+	}
+	return "SMALLINT"
+}
+
+func (db *datastore) typeText() string {
+	return "TEXT"
+}
+
+func (db *datastore) typeChar(l int) string {
+	if db.driverName == driverSQLite {
+		return "TEXT"
+	}
+	return fmt.Sprintf("CHAR(%d)", l)
+}
+
+func (db *datastore) typeBool() string {
+	if db.driverName == driverSQLite {
+		return "INTEGER"
+	}
+	return "TINYINT(1)"
+}
+
+func (db *datastore) typeDateTime() string {
+	return "DATETIME"
+}
+
+func (db *datastore) engine() string {
+	if db.driverName == driverSQLite {
+		return ""
+	}
+	return " ENGINE = InnoDB"
+}

migrations/migrations.go

@@ -0,0 +1,116 @@
+/*
+ * Copyright © 2019 A Bunch Tell LLC.
+ *
+ * This file is part of WriteFreely.
+ *
+ * WriteFreely is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, included
+ * in the LICENSE file in this source code package.
+ */
+
+// Package migrations contains database migrations for WriteFreely
+package migrations
+
+import (
+	"database/sql"
+	"github.com/writeas/web-core/log"
+)
+
+// TODO: refactor to use the datastore struct from writefreely pkg
+type datastore struct {
+	*sql.DB
+	driverName string
+}
+
+func NewDatastore(db *sql.DB, dn string) *datastore {
+	return &datastore{db, dn}
+}
+
+// TODO: use these consts from writefreely pkg
+const (
+	driverMySQL  = "mysql"
+	driverSQLite = "sqlite3"
+)
+
+type Migration interface {
+	Description() string
+	Migrate(db *datastore) error
+}
+
+type migration struct {
+	description string
+	migrate     func(db *datastore) error
+}
+
+func New(d string, fn func(db *datastore) error) Migration {
+	return &migration{d, fn}
+}
+
+func (m *migration) Description() string {
+	return m.description
+}
+
+func (m *migration) Migrate(db *datastore) error {
+	return m.migrate(db)
+}
+
+var migrations = []Migration{}
+
+func Migrate(db *datastore) error {
+	var version int
+	var err error
+	if db.tableExists("appmigrations") {
+		err = db.QueryRow("SELECT MAX(version) FROM appmigrations").Scan(&version)
+	} else {
+		log.Info("Initializing appmigrations table...")
+		version = 0
+		_, err = db.Exec(`CREATE TABLE appmigrations (
+			version ` + db.typeInt() + ` NOT NULL,
+			migrated ` + db.typeDateTime() + ` NOT NULL,
+			result ` + db.typeText() + ` NOT NULL
+		) ` + db.engine() + `;`)
+		if err != nil {
+			return err
+		}
+	}
+
+	if len(migrations[version:]) > 0 {
+		for i, m := range migrations[version:] {
+			curVer := version + i + 1
+			log.Info("Migrating to V%d: %s", curVer, m.Description())
+			err = m.Migrate(db)
+			if err != nil {
+				return err
+			}
+
+			// Update migrations table
+			_, err = db.Exec("INSERT INTO appmigrations (version, migrated, result) VALUES (?, "+db.now()+", ?)", curVer, "")
+			if err != nil {
+				return err
+			}
+		}
+	} else {
+		log.Info("Database up-to-date. No migrations to run.")
+	}
+
+	return nil
+}
+
+func (db *datastore) tableExists(t string) bool {
+	var dummy string
+	var err error
+	if db.driverName == driverSQLite {
+		err = db.QueryRow("SELECT name FROM sqlite_master WHERE type = 'table' AND name = ?", t).Scan(&dummy)
+	} else {
+		err = db.QueryRow("SHOW TABLES LIKE ?", t).Scan(&dummy)
+	}
+	switch {
+	case err == sql.ErrNoRows:
+		return false
+	case err != nil:
+		log.Error("Couldn't SHOW TABLES: %v", err)
+		return false
+	}
+
+	return true
+}