fix: repair Docker dev-environment build and clarify native setup

The documented setup was failing. The native path assumes a Debian host
with LLVM 13, but aWsm's llvm-alt bindings call LLVM C-API functions
(LLVMBuildCall, LLVMBuildLoad) removed in LLVM 15+, so the build fails to
link against newer system LLVM (e.g. LLVM 21 on Ubuntu 24.04). The Docker
route exists for exactly this reason but had bit-rotted in several places.

Dockerfile.x86_64:
- Install `hey` from focal's universe repo instead of downloading the
  prebuilt binary, whose hey-release S3/GCS URLs now return 403.
- Add `git config --system --add safe.directory '*'` so the root-run
  `make install` doesn't abort with "dubious ownership" on the
  host-owned, bind-mounted /sledge.
- Set RUSTUP_HOME/CARGO_HOME to the dev user's install so the root-run
  build can resolve the default Rust toolchain instead of failing with
  "no default is configured".

Makefile:
- Make the wasm_apps symlink rule idempotent (ln -srfn). The symlink is
  committed to the repo, so it already exists on a fresh clone and the
  old `ln -sr` failed with "File exists", breaking `make install`.

README.md:
- Recommend the Docker route and add an explicit caveat to the native
  section documenting the LLVM-13/Debian requirement and why Ubuntu 24.04
  (and other non-LLVM-13 hosts) cannot use it.

Verified end-to-end via `./devenv.sh setup`: aWsm, the runtime, and all
benchmark apps build, and the runtime serves fibonacci, gocr, and
resize_image requests with correct responses.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: bushidocodes

Dockerfile.x86_64

@@ -5,7 +5,6 @@ ENV LLVM_VERSION=13
 ENV WASI_SDK_VERSION=12
 
 ARG DEBIAN_FRONTEND=noninteractive
-ARG HEY_URL=https://hey-release.s3.us-east-2.amazonaws.com/hey_linux_amd64
 ARG WASI_SDK_URL=https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-$WASI_SDK_VERSION/wasi-sdk_$WASI_SDK_VERSION.0_amd64.deb
 ARG SHFMT_URL=https://github.com/mvdan/sh/releases/download/v3.2.4/shfmt_v3.2.4_linux_amd64
 ARG SHELLCHECK_URL=https://github.com/koalaman/shellcheck/releases/download/stable/shellcheck-stable.linux.x86_64.tar.xz
@@ -32,6 +31,11 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 	libtool \
 	pkg-config
 
+# The repo is bind-mounted from the host, so its files are owned by the host user
+# while the build runs as root (docker exec -u 0). Modern git rejects this as
+# "dubious ownership", so whitelist any directory for all users in the image.
+RUN git config --system --add safe.directory '*'
+
 # Needed to install from http endpoints via curl or wget
 RUN apt-get update && apt-get install -y --no-install-recommends \
 	curl \
@@ -43,12 +47,15 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 	wget
 
 # Test Script Stuff
+# hey is a load generator used by the test workloads (focal ships it in universe;
+# the previously-used hey-release S3/GCS binaries now return 403)
 RUN apt-get update && apt-get install -y --no-install-recommends \
 	bc \
 	fonts-dejavu \
 	fonts-cascadia-code \
 	fonts-roboto \
 	gnuplot \
+	hey \
 	httpie \
 	imagemagick \
 	jq \
@@ -57,11 +64,6 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 	pango1.0-tools \
 	wamerican
 
-# Hey is a load generator we have to recklessly download from the 'net, as it is only published to brew
-# Binaries are only provided for AMD64 though, so ARM will have to build from source
-# See https://github.com/rakyll/hey
-RUN wget $HEY_URL -O hey && chmod +x hey && mv hey /usr/bin/hey
-
 # shfmt is a formatter for shell scripts
 RUN wget $SHFMT_URL -O shfmt && chmod +x shfmt && mv shfmt /usr/local/bin/shfmt
 RUN wget $SHELLCHECK_URL -O shellcheck && chmod +x shellcheck && mv shellcheck /usr/local/bin/shellcheck
@@ -110,6 +112,11 @@ RUN cd sledge && ./fix_root.sh
 # Rustup does not cleanly support system installs, so install as non-root user
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --default-toolchain stable --component rustfmt --target wasm32-wasi -y
 ENV PATH=/home/dev/.cargo/bin:$PATH
+# `make install` runs as root (docker exec -u 0), but Rust is installed for the
+# dev user. Point rustup/cargo at dev's install so root resolves the default
+# toolchain instead of failing with "no default is configured".
+ENV RUSTUP_HOME=/home/dev/.rustup
+ENV CARGO_HOME=/home/dev/.cargo
 RUN cargo install --debug cargo-audit cargo-watch rsign2
 
 # We need to set the locale for pango-view

Makefile

@@ -50,9 +50,12 @@ applications:
 applications.clean:
 	make -C applications clean
 
-# Instead of having two copies of wasm_apps, just link to the awsm repo's copy
+# Instead of having two copies of wasm_apps, just link to the awsm repo's copy.
+# -f -n make this idempotent: the symlink is committed to the repo, so it already
+# exists on a fresh clone and on rebuilds; without these flags ln fails with
+# "File exists" and breaks `make install`.
 wasm_apps:
-	ln -sr awsm/applications/wasm_apps/ applications/
+	ln -srfn awsm/applications/wasm_apps/ applications/wasm_apps
 
 # Tests
 .PHONY: test

README.md

@@ -4,18 +4,11 @@
 
 ## Setting up a development environment
 
-### Native on Debian Host
+SLEdge's `aWsm` compiler is built against a **specific LLVM version (LLVM 13)** via the `llvm-alt` Rust bindings. Those bindings use LLVM C-API functions (e.g. `LLVMBuildCall`, `LLVMBuildLoad`) that were **removed in LLVM 15+**, so the build will fail to link against newer LLVM toolchains.
 
-```sh
-git clone https://github.com/gwsystems/sledge-serverless-framework.git
-cd sledge-serverless-framework
-./install_deb.sh
-source ~/.bashrc
-make install
-make test
-```
+**For this reason, the Docker environment below is the recommended way to build SLEdge.** It pins the exact Debian + LLVM 13 + WASI SDK toolchain that the compiler needs, and works on any host with Docker (macOS, Windows/WSL2, or a Linux distro other than the one targeted by `install_deb.sh`).
 
-### Docker
+### Docker (recommended)
 
 **Note: These steps require Docker. Make sure you've got it installed!**
 
@@ -75,6 +68,21 @@ If you are finished working with the SLEdge runtime and wish to remove it, run t
 
 And then simply delete this repository.
 
+### Native build (Debian + LLVM 13 only)
+
+**Caveat:** `install_deb.sh` only works on a host whose package repositories provide **LLVM 13** and `libtinfo5` — in practice a Debian release (or older Ubuntu such as 20.04/22.04) that `apt.llvm.org` still serves LLVM 13 for. It will **not** work on Ubuntu 24.04 (noble) or other distros where LLVM 13 is unavailable: `libtinfo5` has no install candidate, `apt.llvm.org/llvm.sh 13` provides no packages, and the `aWsm` build will fail to link against the newer system LLVM (`undefined symbol: LLVMBuildCall`). Use the Docker route above on those systems.
+
+On a supported host:
+
+```sh
+git clone https://github.com/gwsystems/sledge-serverless-framework.git
+cd sledge-serverless-framework
+./install_deb.sh
+source ~/.bashrc
+make install
+make test
+```
+
 ## Running your first serverless function
 
 An SLEdge serverless function consists of a shared library (\*.so) and a JSON configuration file that determines how the runtime should execute the serverless function. As an example, here is the configuration file for our sample fibonacci function: