maint: update for heroku-24

.github/workflows/tests.yaml

@@ -16,5 +16,5 @@ jobs:
           - heroku-22
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: bash support/test.sh ${{ matrix.stack }}

Dockerfile

@@ -5,6 +5,7 @@ FROM $BUILD_IMAGE AS builder
 ARG STACK
 
 # Emulate the platform where root access is not available
+USER root
 RUN useradd -d /app non-root-user
 RUN mkdir -p /app /cache /env
 RUN chown non-root-user /app /cache /env
@@ -20,6 +21,7 @@ RUN env -i PATH=$PATH HOME=$HOME STACK=$STACK /buildpack/bin/compile /app /cache
 
 
 FROM $RUNTIME_IMAGE
+USER root
 RUN useradd -d /app non-root-user
 USER non-root-user
 COPY --from=builder --chown=non-root-user /app /app

README.md

@@ -4,9 +4,10 @@ This is a [Heroku buildpack](http://devcenter.heroku.com/articles/buildpacks) th
 allows an application to use an [stunnel](http://stunnel.org) to connect securely to
 Heroku Redis.  It is meant to be used in conjunction with other buildpacks.
 
-**This buildpack is only for use with Heroku Redis 4 and 5. For Heroku Redis 6 and newer, use its built-in TLS support instead.**
+> [!WARNING]
+> This buildpack isn’t compatible with [`heroku-24`](article link?) and later. You don’t need this buildpack for Redis 6+, which supports native TLS.
 
-**For more information, see [Securing Heroku Redis](https://devcenter.heroku.com/articles/securing-heroku-redis).**
+> For more information, see [Securing Heroku Redis](https://devcenter.heroku.com/articles/heroku-redis#security-and-compliance).
 
 ## Usage
 

bin/compile

@@ -13,6 +13,16 @@ unset GIT_DIR
 BUILD_DIR=$1
 BUILDPACK_DIR="$(dirname $(dirname $0))"
 
+if ! command -v stunnel4 > /dev/null; then
+
+    echo "! This buildpack uses stunnel, which isn’t supported on heroku-24 and later."
+    echo "! You don’t need this buildpack for Redis 6+. Remove it with the command:"
+    echo "! $ heroku buildpacks:remove heroku/redis"
+    echo "! To use Redis’ native TLS support, see https://devcenter.heroku.com/articles/heroku-redis#security-and-compliance."
+
+    exit 1
+fi
+
 echo "-----> Moving the configuration generation script into app/bin"
 mkdir -p $BUILD_DIR/bin
 cp "$BUILDPACK_DIR/bin/stunnel-conf.sh" $BUILD_DIR/bin/stunnel-conf.sh