fix(recipes): probe the escalation tool before python-dev uses it

internal/recipes/bundled/python-dev/install-alpine.sh

@@ -12,16 +12,34 @@ fi
 stoat_pkg_setup
 stoat_pkg_install python3 py3-pip
 
+# busybox su recognises options anywhere, so a -p among the trailing arguments
+# becomes su's own preserve-environment flag and never reaches the command.
+# Quote the argument list into -c instead of passing it positionally.
+su_user() {
+    quoted=
+    for arg do
+        quoted="$quoted'$(printf '%s' "$arg" | sed "s/'/'\\\\''/g")' "
+    done
+    su -s /bin/sh "$user" -c "exec $quoted"
+}
+
+# Alpine's sudoers file grants root nothing, so sudo is on PATH and refuses
+# every command. Probe each tool once and keep the first that runs.
 as_user() {
-    if command -v runuser >/dev/null 2>&1; then
-        runuser -u "$user" -- "$@"
-    elif command -v sudo >/dev/null 2>&1; then
-        sudo -n -u "$user" -- "$@"
-    else
-        command=$1
-        shift
-        su -s /bin/sh "$user" -c 'exec "$@"' stoat "$command" "$@"
+    if [ -z "${as_user_tool:-}" ]; then
+        if command -v runuser >/dev/null 2>&1 && runuser -u "$user" -- true 2>/dev/null; then
+            as_user_tool=runuser
+        elif command -v sudo >/dev/null 2>&1 && sudo -n -u "$user" -- true 2>/dev/null; then
+            as_user_tool=sudo
+        else
+            as_user_tool=su
+        fi
     fi
+    case "$as_user_tool" in
+    runuser) runuser -u "$user" -- "$@" ;;
+    sudo) sudo -n -u "$user" -- "$@" ;;
+    *) su_user "$@" ;;
+    esac
 }
 
 python_bin=$(command -v python3 2>/dev/null || command -v python 2>/dev/null || true)

internal/recipes/bundled/python-dev/install-arch.sh

@@ -12,16 +12,34 @@ fi
 stoat_pkg_setup
 stoat_pkg_install python python-pip
 
+# busybox su recognises options anywhere, so a -p among the trailing arguments
+# becomes su's own preserve-environment flag and never reaches the command.
+# Quote the argument list into -c instead of passing it positionally.
+su_user() {
+    quoted=
+    for arg do
+        quoted="$quoted'$(printf '%s' "$arg" | sed "s/'/'\\\\''/g")' "
+    done
+    su -s /bin/sh "$user" -c "exec $quoted"
+}
+
+# A sudo binary on PATH is not a working sudo: Alpine's sudoers grants root
+# nothing. Probe each tool once and keep the first that runs.
 as_user() {
-    if command -v runuser >/dev/null 2>&1; then
-        runuser -u "$user" -- "$@"
-    elif command -v sudo >/dev/null 2>&1; then
-        sudo -n -u "$user" -- "$@"
-    else
-        command=$1
-        shift
-        su -s /bin/sh "$user" -c 'exec "$@"' stoat "$command" "$@"
+    if [ -z "${as_user_tool:-}" ]; then
+        if command -v runuser >/dev/null 2>&1 && runuser -u "$user" -- true 2>/dev/null; then
+            as_user_tool=runuser
+        elif command -v sudo >/dev/null 2>&1 && sudo -n -u "$user" -- true 2>/dev/null; then
+            as_user_tool=sudo
+        else
+            as_user_tool=su
+        fi
     fi
+    case "$as_user_tool" in
+    runuser) runuser -u "$user" -- "$@" ;;
+    sudo) sudo -n -u "$user" -- "$@" ;;
+    *) su_user "$@" ;;
+    esac
 }
 
 python_bin=$(command -v python3 2>/dev/null || command -v python 2>/dev/null || true)

internal/recipes/bundled/python-dev/install-debian.sh

@@ -12,16 +12,34 @@ fi
 stoat_pkg_setup
 stoat_pkg_install python3 python3-pip python3-venv
 
+# busybox su recognises options anywhere, so a -p among the trailing arguments
+# becomes su's own preserve-environment flag and never reaches the command.
+# Quote the argument list into -c instead of passing it positionally.
+su_user() {
+    quoted=
+    for arg do
+        quoted="$quoted'$(printf '%s' "$arg" | sed "s/'/'\\\\''/g")' "
+    done
+    su -s /bin/sh "$user" -c "exec $quoted"
+}
+
+# A sudo binary on PATH is not a working sudo: Alpine's sudoers grants root
+# nothing. Probe each tool once and keep the first that runs.
 as_user() {
-    if command -v runuser >/dev/null 2>&1; then
-        runuser -u "$user" -- "$@"
-    elif command -v sudo >/dev/null 2>&1; then
-        sudo -n -u "$user" -- "$@"
-    else
-        command=$1
-        shift
-        su -s /bin/sh "$user" -c 'exec "$@"' stoat "$command" "$@"
+    if [ -z "${as_user_tool:-}" ]; then
+        if command -v runuser >/dev/null 2>&1 && runuser -u "$user" -- true 2>/dev/null; then
+            as_user_tool=runuser
+        elif command -v sudo >/dev/null 2>&1 && sudo -n -u "$user" -- true 2>/dev/null; then
+            as_user_tool=sudo
+        else
+            as_user_tool=su
+        fi
     fi
+    case "$as_user_tool" in
+    runuser) runuser -u "$user" -- "$@" ;;
+    sudo) sudo -n -u "$user" -- "$@" ;;
+    *) su_user "$@" ;;
+    esac
 }
 
 python_bin=$(command -v python3 2>/dev/null || command -v python 2>/dev/null || true)

internal/recipes/bundled/python-dev/install-rpm.sh

@@ -12,16 +12,34 @@ fi
 stoat_pkg_setup
 stoat_pkg_install python3 python3-pip
 
+# busybox su recognises options anywhere, so a -p among the trailing arguments
+# becomes su's own preserve-environment flag and never reaches the command.
+# Quote the argument list into -c instead of passing it positionally.
+su_user() {
+    quoted=
+    for arg do
+        quoted="$quoted'$(printf '%s' "$arg" | sed "s/'/'\\\\''/g")' "
+    done
+    su -s /bin/sh "$user" -c "exec $quoted"
+}
+
+# A sudo binary on PATH is not a working sudo: Alpine's sudoers grants root
+# nothing. Probe each tool once and keep the first that runs.
 as_user() {
-    if command -v runuser >/dev/null 2>&1; then
-        runuser -u "$user" -- "$@"
-    elif command -v sudo >/dev/null 2>&1; then
-        sudo -n -u "$user" -- "$@"
-    else
-        command=$1
-        shift
-        su -s /bin/sh "$user" -c 'exec "$@"' stoat "$command" "$@"
+    if [ -z "${as_user_tool:-}" ]; then
+        if command -v runuser >/dev/null 2>&1 && runuser -u "$user" -- true 2>/dev/null; then
+            as_user_tool=runuser
+        elif command -v sudo >/dev/null 2>&1 && sudo -n -u "$user" -- true 2>/dev/null; then
+            as_user_tool=sudo
+        else
+            as_user_tool=su
+        fi
     fi
+    case "$as_user_tool" in
+    runuser) runuser -u "$user" -- "$@" ;;
+    sudo) sudo -n -u "$user" -- "$@" ;;
+    *) su_user "$@" ;;
+    esac
 }
 
 python_bin=$(command -v python3 2>/dev/null || command -v python 2>/dev/null || true)

internal/recipes/samples_test.go

@@ -260,6 +260,28 @@ func TestBundledPythonDevCreatesAndPreservesVenv(t *testing.T) {
 	}
 }
 
+// Alpine ships a sudoers file that grants root nothing, so sudo is on PATH and
+// still refuses every command. The recipe must fall through to su instead of
+// failing the runcmd and leaving cloud-init in error.
+func TestBundledPythonDevFallsBackWhenEscalationRefuses(t *testing.T) {
+	t.Setenv("STOAT_FAKE_NO_ESCALATION", "1")
+	account := currentTestAccount(t)
+	root := t.TempDir()
+
+	for _, guestOS := range []string{"alpine", "debian", "arch", "fedora"} {
+		body := bundledScript(t, "python-dev", guestOS)
+		venvDir := filepath.Join(root, guestOS, "env")
+		output, err := runBundledPython(t, body, account.Username, venvDir,
+			filepath.Join(root, guestOS+"-output"), filepath.Join(root, guestOS+"-calls"))
+		if err != nil {
+			t.Fatalf("%s: %v\n%s", guestOS, err, output)
+		}
+		if _, err := os.Stat(filepath.Join(venvDir, "pyvenv.cfg")); err != nil {
+			t.Errorf("%s: environment was not created: %v", guestOS, err)
+		}
+	}
+}
+
 func TestBundledPythonDevRefusesInvalidTargets(t *testing.T) {
 	body := bundledScript(t, "python-dev", "alpine")
 	account := currentTestAccount(t)
@@ -449,6 +471,10 @@ func writeHermeticCommandFakes(t *testing.T, bin string) {
 	t.Helper()
 	accountSwitch := `#!/bin/sh
 set -eu
+if [ -n "${STOAT_FAKE_NO_ESCALATION:-}" ]; then
+  echo "root is not in the sudoers file." >&2
+  exit 1
+fi
 while [ "$#" -gt 0 ]; do
   case "$1" in
     -u|-g|-s) shift 2;;
@@ -464,16 +490,20 @@ exec "$@"
 			t.Fatal(err)
 		}
 	}
+	// busybox su, which is what Alpine has, recognises options anywhere on the
+	// command line. A -p among the trailing arguments becomes su's own
+	// preserve-environment flag and never reaches the command, so this fake
+	// drops every dash argument and passes nothing positional to the shell.
 	if err := os.WriteFile(filepath.Join(bin, "su"), []byte(`#!/bin/sh
 set -eu
 user=
 command=
 while [ "$#" -gt 0 ]; do
   case "$1" in
+    -c) command=$2; shift 2;;
     -s) shift 2;;
     -*) shift;;
-    -c) command=$2; shift 2; break;;
-    *) user=$1; shift;;
+    *) [ -n "$user" ] || user=$1; shift;;
   esac
 done
 [ -n "$command" ]