From af33f7eb124b51ff6d9cdf9b428643e2246c8cbb Mon Sep 17 00:00:00 2001
From: En-En <39373446+En-En-Code@users.noreply.github.com>
Date: Wed, 27 Aug 2025 00:17:25 +0000
Subject: [PATCH] ci: comment logic of set-vars.sh

---
 .github/workflows/set-vars.sh       | 6 ++++++
 .github/workflows/ubuntu.dockerfile | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/set-vars.sh b/.github/workflows/set-vars.sh
index 3db73aa..edfa0ec 100755
--- a/.github/workflows/set-vars.sh
+++ b/.github/workflows/set-vars.sh
@@ -1,5 +1,7 @@
 #!/bin/sh
 
+# Find the line specifying the version number for the Rust toolchain, then
+# extract that version number. Failure to do so aborts the CI run.
 msrv=$(
     awk '/^rust-version = "[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+"$/ {
       print substr($NF, 2, length($NF) - 2)
@@ -10,6 +12,10 @@ if [ -z $msrv ]; then
     exit 1
 fi
 
+# Check for one of two conditions to regenerate the Docker image:
+# (These conditions must be met on `main` and not a PR branch, see ci.yml)
+# 1. An annotated tag was found when fetching the tags at depth 1 (tags on HEAD)
+# 2. "$UBUNTU_DOCKERFILE" was changed between HEAD and the prior commit (HEAD~1)
 git fetch --depth=1 origin +refs/tags/*:refs/tags/*
 if ! git diff HEAD~1 --quiet -- "$UBUNTU_DOCKERFILE" ||
     git describe --candidates=0; then
diff --git a/.github/workflows/ubuntu.dockerfile b/.github/workflows/ubuntu.dockerfile
index 4484ed4..041e341 100644
--- a/.github/workflows/ubuntu.dockerfile
+++ b/.github/workflows/ubuntu.dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:latest
+FROM ubuntu:24.04
 
 ARG DEBIAN_FRONTEND=noninteractive
 ENV TZ=Etc/UTC