add support for integrated database schema migrations

added the "initprovider" command to initialize the database structure.
If we change the database schema the required changes will be checked
at startup and automatically applyed.

dataprovider/pgsql.go

@@ -3,10 +3,22 @@ package dataprovider
 import (
 	"database/sql"
 	"fmt"
+	"strings"
 
 	"github.com/drakkan/sftpgo/logger"
 )
 
+const (
+	pgsqlUsersTableSQL = `CREATE TABLE "{{users}}" ("id" serial NOT NULL PRIMARY KEY, "username" varchar(255) NOT NULL UNIQUE,
+"password" varchar(255) NULL, "public_keys" text NULL, "home_dir" varchar(255) NOT NULL, "uid" integer NOT NULL,
+"gid" integer NOT NULL, "max_sessions" integer NOT NULL, "quota_size" bigint NOT NULL, "quota_files" integer NOT NULL,
+"permissions" text NOT NULL, "used_quota_size" bigint NOT NULL, "used_quota_files" integer NOT NULL,
+"last_quota_update" bigint NOT NULL, "upload_bandwidth" integer NOT NULL, "download_bandwidth" integer NOT NULL,
+"expiration_date" bigint NOT NULL, "last_login" bigint NOT NULL, "status" integer NOT NULL, "filters" text NULL,
+"filesystem" text NULL);`
+	pgsqlSchemaTableSQL = `CREATE TABLE "schema_version" ("id" serial NOT NULL PRIMARY KEY, "version" integer NOT NULL);`
+)
+
 // PGSQLProvider auth provider for PostgreSQL database
 type PGSQLProvider struct {
 	dbHandle *sql.DB
@@ -102,3 +114,32 @@ func (p PGSQLProvider) close() error {
 func (p PGSQLProvider) reloadConfig() error {
 	return nil
 }
+
+// initializeDatabase creates the initial database structure
+func (p PGSQLProvider) initializeDatabase() error {
+	sqlUsers := strings.Replace(pgsqlUsersTableSQL, "{{users}}", config.UsersTable, 1)
+	tx, err := p.dbHandle.Begin()
+	if err != nil {
+		return err
+	}
+	_, err = tx.Exec(sqlUsers)
+	if err != nil {
+		tx.Rollback()
+		return err
+	}
+	_, err = tx.Exec(pgsqlSchemaTableSQL)
+	if err != nil {
+		tx.Rollback()
+		return err
+	}
+	_, err = tx.Exec(initialDBVersionSQL)
+	if err != nil {
+		tx.Rollback()
+		return err
+	}
+	return tx.Commit()
+}
+
+func (p PGSQLProvider) migrateDatabase() error {
+	return sqlCommonMigrateDatabase(p.dbHandle)
+}