relup(4)

📦
version 29.1.1 · 3 versions
, in arch rolling, nixos 26.05, nixpkgs unstable, ubuntu stonking

💖 relup — the release glow-up file 💖

okay bestie, gather round, because this one is the manual page for relup (section 4 of the manual, iykyk), and it's literally the blueprint for how a release gets upgraded. no cap.

✨ DESCRIPTION ✨

so. the release upgrade file describes how a release is upgraded in a running system. that's the whole vibe. it's the instructions sheet, the choreography, the "okay everyone here's what changes" note. 🎀

and the best part? you do not hand-write this. it's automatically generated by systools:make_relup/3,4, which takes these as input:

  • a release resource file (.rel) 🦋
  • application resource files (.app) 🌸
  • application upgrade files (.appup) 💅

📁 File Syntax 📁

in a target system, the release upgrade file is to be located in directory $ROOT/releases/Vsn. that's its home. that's where it lives. 🏠

the relup file contains one single Erlang term, and that term defines the instructions used to upgrade the release. here's the syntax, verbatim, don't touch it:

{Vsn,
  [{UpFromVsn, Descr, Instructions}, ...],
  [{DownToVsn, Descr, Instructions}, ...]}.

Vsn = string()
  • 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. so like, you put a lil something in, and it comes back out over there. 🫶
  • 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. the way that high-level stuff gets translated down to low-level... obsessed. 🔥
  • DownToVsn = string() — Earlier version of the release to downgrade to. ⬇️ (yes bestie, we can go back too, it's giving reversible.)

👀 See Also 👀

app(4), appup(4), rel(4), release_handler, systools

go read those too, fr fr. no skipping. 💀

and that's the whole page, periodt. 💜 this lil masterpiece came to you from Ericsson AB, from the sasl 4.4 era, and it's been sitting pretty in the relup(4) slot ever since. mwah. 💅✨

📦 where this page comes from