Introduction

ScriptEngine is a lightweight and extensible framework and tool for executing scripts written in YAML. The main purpose of ScriptEngine is to replace shell scripts in situations where highly configurable and modular scripts are needed. ScriptEngine relies on YAML and makes extensive use of Jinja2 templating to provide a comprehensive scripting language. This allows users to put focus on the description of tasks, rather than their implementation. The description of complex tasks should be nearly as short and clear as for simpler ones.

The ScriptEngine concept separates scripts (what to do) from the implementation of tasks (how to do things), and also from the actual execution environment (the script engine instances). This modularity allows the provision of different execution models (e.g. sequential or parallel; local or remote) within the same framework.

ScriptEngine provides a concise set of basic tasks that users can use to write their scripts. However, extensibility is a fundamental principle for ScriptEngine. Complementary task sets are provided as Python packages that can be loaded into ScriptEngine at run time. Thus, the capabilities of ScriptEngine scripts extend to features provided by task set packages available from package repositories or locally.

ScriptEngine tasks are simple Python classes with a run() method, which means that it is rather easy to build new tasks sets for particular needs. And because everything is based on Python3, there is a wide range of modules available to get the actual work done easily and efficiently.

ScriptEngine is strongly influenced by Ansible. In fact, ScriptEngine was developed because it met almost, but not quite, the needs of the author. Here are some important differences:

  • Tasks are executed on a single host, often the host where the ScriptEngine command line tool is running. This is not an implication of any ScriptEngine concept, though. It would be possible to implement ScriptEngine instances that execute tasks remotely, or on multiple hosts.
  • Contrary to Ansible, ScriptEngine tasks specify actions, not states.
  • ScriptEngine is not focused on system administration. Although this is not part of the underlying concept, it will most probably reflect in the selection of available tasks.
  • ScriptEngine’s implementation of tasks is extremely lightweight, they’re basically single Python functions. Almost every user should be able to add new tasks to ScriptEngine.

ScriptEngine is easily installed from the Python Package Index (PyPI) with the pip package manager.