relup
Description
The release upgrade file describes how a release is upgraded in a running system.
This file is automatically generated by systools:make_relup/3,4, using a release resource file (.rel), application resource files (.app), and application upgrade files (.appup) as input.
File Syntax
In a target system, the release upgrade file is to be located in directory $ROOT/releases/Vsn.
The relup file contains one single Erlang term, which defines the instructions used to upgrade the release. The file has the following syntax:
{Vsn, [{UpFromVsn, Descr, Instructions}, ...], [{DownToVsn, Descr, Instructions}, ...]}.
- Vsn = string()
Current release version.
- UpFromVsn = string()
Earlier version of the release to upgrade from.
- Descr = term()
A user-defined parameter passed from the function systools:make_relup/3,4. It is used in the return value of release_handler:install_release/1,2.
- Instructions
A list of low-level release upgrade instructions, see appup(4). It consists of the release upgrade instructions from the respective application upgrade files (high-level instructions are translated to low-level instructions), in the same order as in the start script.
- DownToVsn = string()
Earlier version of the release to downgrade to.