db-backup

#!/bin/sh

# version=2013-07-16:0.0.0:go2null
# * Initial release
# * Automated retrieving the database variables using code from
#     http://www.redmine.org/projects/redmine/wiki/HowTo_Migrate_Redmine_to_a_new_server_to_a_new_Redmine_version
# * Can specifiy backup file as input parameter
# version=2013-08-01:0.1.0:go2null
# * NEW: acepts unzipped backup file to restore
# version=2013-08-22:0.1.2:go2null
# * FIX: fatal error in gzip check
# * FIX: .gz not removed from filename after decompression
version=2015-12-03:0.2.0:go2null
# * NEW: Refactor to include backup and restore functionality


# ** HELPER FUNCTIONS ** #

print_help() {
	self="${0#*/}"
	printf %s "$self, version $version
Backup and restore a Ruby on Rails MySQL database

Usage:  $self [action] [options]

Actions:
  backup            Perform backup. [Default]
  restore           Perform restore.

Options:
  -b, --backup-dir  Where to save/find the database dump file. [Default: \$HOME]
                      Ignored if <backup-file> is a path.
  -f, --backup-file Database dump file. [Default: db_<db-name>_<rails-env>.sql.gz]
                      Backup:  Existing file will be renamed with file modification time.
                      Restore: File does not have to be gzipped.
  -r, --rails-root  Rails root directory. Default: [Default: \$PWD]
  -e, --rails-env   Rails environment to dump/restore to. [Default: production]
  -h, --help        Display help text and exit.
  -v, --verbose     Display messages.
  -V, --version     Display version info and exit.

"
}

print_message() {
	case "$1" in
    'error') shift; printf '%s\n' "!! ERROR: $@"; exit 1; ;;
    'warn' ) shift; printf '%s\n' "!! WARNING: $@"        ;;
    *      )        printf '%s\n' "$@"                    ;;
	esac
}

# Sets: action, bak_dir, rails_env, rails_root
set_defaults() {
	action='backup'
	bak_dir="$HOME"
	rails_env='production'
	rails_root="$(pwd)"
}

# Sets: action, bak_dir, bak_file_path, rails_env, rails_root
get_params() {
	# get input options
	while [ $# -gt 0 ]; do
		case "$1" in
			'backup'            ) action='backup'                 ;;
			'restore'           ) action='restore'                ;;
			'-b'|'--backup-dir' ) bak_dir="$2"        ; shift;    ;;
			'-f'|'--backup-file') bak_file_path="$2"  ; shift;    ;;
			'-e'|'--rails-env'  ) rails_env="$2"      ; shift;    ;;
			'-r'|'--rails-root' ) rails_root="$2"     ; shift;    ;;
			'-h'|'--help'       ) print_help          ; exit ;    ;;
			'-v'|'--verbose'    ) verbose='--verbose'             ;;
			'-V'|'--version'    ) echo "$version"     ; exit ;    ;;
			*                   ) echo "Invalid parameter '$1'"   ;;
		esac
		shift
	done
}

# Gets: rails_env, rails_root
# Sets: db_name, db_user, db_pass
set_rails() {
	# rails
	rails_db_conf="$rails_root/config/database.yml"
	[ -r "$rails_db_conf" ] || print_message 'error' "Invalid database.yml '$rails_db_conf'."
	# database
	db_name="$(grep -A 5 "^$rails_env:" "$rails_db_conf" |sed -nr 's/.*database:[ \t]*(.*)/\1/p')"
	db_user="$(grep -A 5 "^$rails_env:" "$rails_db_conf" |sed -nr 's/.*username:[ \t]*(.*)/\1/p')"
	db_pass="$(grep -A 5 "^$rails_env:" "$rails_db_conf" |sed -nr 's/.*password:[ \t]*(.*)/\1/p')"
	if [ -z "$db_name" ] || [ -z "$db_user" ]; then
		print_message 'error' "Invalid database.yml '$rails_db_conf'."
	fi
	# special handing for empty password string as `bash` is escaping it badly
	if [ "$db_pass" = '""' ] || [ "$db_pass" = "''" ]; then
		unset db_pass
	fi
}

# Gets: db_env, db_name
# Sets: bak_dir, bak_file_path, bak_file_name
set_backup() {
	# backup file
	if [ -z "$bak_file_path" ]; then
		bak_file_name="db_${db_name}_${rails_env}.sql.gz"
		bak_file_path="$bak_dir/$bak_file_name"
	else
		bak_file_name="${bak_file_path##*/}"
		# backup dir
		bak_file_dir="${bak_file_path%/*}"
		[ "$bak_file_path" != "$bak_file_dir" ] && bak_dir="$bak_file_dir"
	fi
}

# Gets: bak_dir
# Sets: bak_file_name, bak_file_path, dbdumper, zipper
validate_backup() {
	dbdumper='mysqldump'
	dbdumper="$(type -ap "$dbdumper" | tail -1)"
	[ -z "$dbdumper" ] && print_message 'error' "Cannot find '$dbdumper'."

	zipper='gzip'
	zipper="$(type -ap "$zipper" | tail -1)"
	if [ -z "$zipper" ]; then
		print_message 'warn' 'Cannot find "gzip"'
		bak_file_name="${bak_file_name%.gz}"
		bak_file_path="${bak_file_path%.gz}"
	elif [ "${bak_file_name%.gz}" = "$bak_file_name" ]; then
		# ensure .gz extension
		bak_file_name="${bak_file_name}.gz"
		bak_file_path="${bak_file_path}.gz"
	fi

	[ -w "$bak_dir" ] || print_message 'error' "Invalid backup directory '$bak_dir'"

	[ -e "$bak_file_path" ] && move_existing_backup
}

# Gets: bak_dir, bak_file_name, bak_file_path
move_existing_backup() {
	bak_file_timestamp="$(find "${bak_dir}/" -maxdepth 1 -type f -name "${bak_file_name}" -printf '%TY%Tm%Td-%TH%TM%TS')"
	# strip fractional seconds
	bak_file_timestamp="${bak_file_timestamp%.*}"

	# bak_file_name = db_redmine_production.sql[.gz]
	bak_file_ext="${bak_file_name#*.sql}"
	if [ "$bak_file_ext" = "$bak_file_name" ]; then
		# bak_file_name = db_redmine_production
		bak_file_basename="$bak_file_name"
		unset bak_file_ext
	else
		# bak_file_name = db_redmine_production.sql[.gz]
		bak_file_basename="${bak_file_name%.sql*}"
		bak_file_ext=".sql$bak_file_ext"
	fi

	bak_file_timestamped="$bak_dir/$bak_file_basename-$bak_file_timestamp$bak_file_ext"
	if ! mv "$bak_file_path" "$bak_file_timestamped" &>/dev/null; then
		print_message 'error' "Cannot move existing backup file '${bak_file_path}'"
	fi
}

# Gets: bak_file_path, db_name, db_pass, db_user, dbdumper, zipper
do_backup() {
	print_message "** Backing up '$db_name' to '$bak_file_path'. **"

	if [ -z "$zipper" ]; then
		$dbdumper --verbose --user="$db_user" --password="$db_pass" "$db_name" \
			          > "$bak_file_path"
	else
		$dbdumper --verbose --user="$db_user" --password="$db_pass" "$db_name" \
			| $zipper > "$bak_file_path"
	fi

	if [ $? -gt 0 ]; then
		print_message 'error' "Database '$db_name' back up to '$bak_file_path' failed."
	else
		print_message "** Database '$db_name' backed up to '$bak_file_path'. **"
	fi
}

# Sets: bak_file_name, bak_file_path, dbclient, unzipper
validate_restore() {
	dbclient='mysql'
	dbclient="$(type -ap "$dbclient" | tail -1)"
	[ -z "$dbclient" ] && print_message 'error' "Cannot find '$dbclient'."

	find_file_path

	# check whether need to uncompress backup
	if [ "${bak_file_name#*.sql}" = '.gz' ]; then
		unzipper='gunzip'
		unzipper="$(type -ap "$unzipper" | tail -1)"
		[ -z "$unzipper" ] && print_message 'error' "Cannot find '$unzipper'."
	fi
}

# Sets: bak_file_name, bak_file_path
find_file_path() {
	# try to find file
	if [ -e "$bak_file_path" ]; then
		validate_file_path
	else
		bak_file_path="${bak_file_path%.gz}"
	  if [ -e "$bak_file_path" ]; then
			validate_file_path
		else
			bak_file_path="${bak_file_path%.sql}"
			validate_file_path
		fi
	fi
	bak_file_name="${bak_file_path##*/}"
}

# Gets: bak_file_path
validate_file_path() {
	if [ ! -r "$bak_file_path" ]; then
		print_message 'error' "Invalid backup file to restore '$bak_file_path'."
	fi
}

# Gets: db_name, bak_file_path
do_restore() {
	print_message "** Restoring '$db_name' from '$bak_file_path'.**"

	# uncompress backup, if needed
	if [ -z "$unzipper" ]; then
		$dbclient $verbose --user="$db_user" --password="$db_pass" "$db_name"
	else
		$unzipper "$bak_file_path" \
			| $dbclient $verbose --user="$db_user" --password="$db_pass" "$db_name"
	fi

	if [ $? -gt 0 ]; then
		print_message 'error' "Database '$db_name' restore from '$bak_file_path' failed."
	else
		print_message "** Database '$db_name' restored from '$bak_file_path'. **"
	fi

}

#** MAIN ** #
set_defaults
get_params "$@"
set_rails
set_backup
if [ "$action" = "backup" ]; then
	validate_backup
	do_backup
else
	validate_restore
	do_restore
fi