APPUP_SRC.md

Using an .appup.src file

The plugin will search for any files ending in .appup.src, evaluate them and write the result to the .appup file. The last term for the expression in this file should a properly formatted .appup term. Here is a simple example in the relapp test release:

Version = "1.0.17",
{ok, V} = relapp_m1:test("1.0.16"),
UpFrom = DownTo = V,
{Version,
    [{UpFrom,
        [{load_module,relapp_m1,brutal_purge,brutal_purge,
                              [relapp_srv2]},
                 {update,relapp_srv,
                         {advanced,[]},
                         brutal_purge,brutal_purge,
                         [relapp_m1]},
                 {update,relapp_srv2,
                         {advanced,[]},
                         brutal_purge,brutal_purge,[]}]}],
    [{DownTo,
        [{update,relapp_srv2,
                         {advanced,[]},
                         brutal_purge,brutal_purge,[]},
                 {update,relapp_srv,
                         {advanced,[]},
                         brutal_purge,brutal_purge,
                         [relapp_m1]},
                 {load_module,relapp_m1,brutal_purge,brutal_purge,
                              [relapp_srv2]}]}
]}.

Note that we are able to access methods in our codebase (ie. the relapp_m1 module).

Templated .appup.src

Before being evaluated there is a template variable substitution phase using mustache templates, the following variables are available:

• vsn - the current release version

Here is an example of this in practice in the relapp test release:

{"{{vsn}}",
    [
     {<<".*">>, [{restart_application, relapp}]}
    ],
    [
     {<<".*">>, [{restart_application, relapp}]}
    ]
}.

Built-in variables

The following built-in variables are exposed and made available when evaluating the .appup.src:

• STATE - rebar3's internal state

Helper methods

The plugin exposes these methods in order to ease extraction of useful information from the state:

• rebar3_appup_utils:find_app_info(Name :: binary(), State :: #state_t{}) -> #app_info_t{}. Given an app name obtains it's app info record from rebar's state, rebar_app_info methods can then be used to extract all kinds of information.

Here is another example from the relapp test release:

%% find our app info in rebar's STATE
AppInfo = rebar3_appup_utils:find_app_info(<<"relapp">>, STATE),
"{{vsn}}" = rebar_app_info:original_vsn(AppInfo),
{"{{vsn}}",
    [
     {<<".*">>, [{restart_application, relapp}]}
    ],
    [
     {<<".*">>, [{restart_application, relapp}]}
    ]
}.