Re-implement ad6ae240 without behavior change

tasks/read_file.json

@@ -7,7 +7,6 @@
     }
   },
   "implementations": [
-    {"name": "read_file.rb", "requirements": ["puppet-agent"], "input_method": "stdin"},
     {"name": "read_file.sh", "requirements": ["shell"], "input_method": "environment"}
   ]
 }

tasks/read_file.sh

@@ -1,10 +1,21 @@
 #!/bin/bash
 
 main() {
+	local python_exec=""
+
+	# check if any python exec is available on the remote system. error out if not
+	while :; do
+		python_exec=$(command -v python)  && break
+		python_exec=$(command -v python3) && break
+		python_exec=$(command -v python2) && break
+		echo "Error: No Python version 2 or 3 interpreter found."
+		exit 1
+	done
+
 	if [ -r "$PT_path" ]; then
 		cat <<-EOS
 			{
-				"content": $(python_cmd -c "import json; print json.dumps(open('$PT_path','r').read())")
+				"content": $($python_exec -c "import json; print json.dumps(open('$PT_path','r').read())")
 			}
 		EOS
 	else
@@ -17,14 +28,4 @@ main() {
 	fi
 }
 
-python_cmd() {
-	if command -v python >/dev/null 2>&1; then
-		python "$@"
-	else
-		python3 "$@"
-	fi
-}
-
 main "$@"
-exit_code=$?
-exit $exit_code