refactor: replace with a simpler composite action

install-nix.sh

@@ -0,0 +1,86 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if type -p nix &>/dev/null ; then
+  echo "Aborting: Nix is already installed at $(type -p nix)"
+  exit
+fi
+
+# Create a temporary workdir
+workdir=$(mktemp -d)
+trap 'rm -rf "$workdir"' EXIT
+
+# Configure Nix
+add_config() {
+  echo "$1" | tee -a "$workdir/nix.conf" >/dev/null
+}
+# Set jobs to number of cores
+add_config "max-jobs = auto"
+# Allow binary caches for user
+add_config "trusted-users = root $USER"
+# Append extra nix configuration if provided
+if [[ $INPUT_EXTRA_NIX_CONFIG != "" ]]; then
+  add_config "$INPUT_EXTRA_NIX_CONFIG"
+fi
+if [[ ! $INPUT_EXTRA_NIX_CONFIG =~ "experimental-features" ]]; then
+  add_config "experimental-features = nix-command flakes"
+fi
+
+# Nix installer flags
+installer_options=(
+  --no-channel-add
+  --darwin-use-unencrypted-nix-store-volume
+  --nix-extra-conf-file "$workdir/nix.conf"
+)
+
+# only use the nix-daemon settings if on darwin (which get ignored) or systemd is supported
+if [[ $OSTYPE =~ darwin || -e /run/systemd/system ]]; then
+  installer_options+=(
+    --daemon
+    --daemon-user-count "$(python -c 'import multiprocessing as mp; print(mp.cpu_count() * 2)')"
+  )
+else
+  # "fix" the following error when running nix*
+  # error: the group 'nixbld' specified in 'build-users-group' does not exist
+  add_config "build-users-group ="
+  sudo mkdir -p /etc/nix
+  sudo chmod 0755 /etc/nix
+  sudo cp $workdir/nix.conf /etc/nix/nix.conf
+fi
+
+if [[ $INPUT_INSTALL_OPTIONS != "" ]]; then
+  IFS=' ' read -r -a extra_installer_options <<< "$INPUT_INSTALL_OPTIONS"
+  installer_options=("${extra_installer_options[@]}" "${installer_options[@]}")
+fi
+
+echo "installer options: ${installer_options[*]}"
+
+# There is --retry-on-errors, but only newer curl versions support that
+curl_retries=5
+while ! curl -sS -o "$workdir/install" -v --fail -L "${INPUT_INSTALL_URL:-https://nixos.org/nix/install}"
+do
+  sleep 1
+  ((curl_retries--))
+  if [[ $curl_retries -le 0 ]]; then
+    echo "curl retries failed" >&2
+    exit 1
+  fi
+done
+
+sh "$workdir/install" "${installer_options[@]}"
+
+if [[ $OSTYPE =~ darwin ]]; then
+  # macOS needs certificates hints
+  cert_file=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt
+  echo "NIX_SSL_CERT_FILE=$cert_file" >> "$GITHUB_ENV"
+  export NIX_SSL_CERT_FILE=$cert_file
+  sudo launchctl setenv NIX_SSL_CERT_FILE "$cert_file"
+fi
+
+# Set paths
+echo "/nix/var/nix/profiles/default/bin" >> "$GITHUB_PATH"
+echo "/nix/var/nix/profiles/per-user/$USER/profile/bin" >> "$GITHUB_PATH"
+
+if [[ $INPUT_NIX_PATH != "" ]]; then
+  echo "NIX_PATH=${INPUT_NIX_PATH}" >> "$GITHUB_ENV"
+fi