tackle 0.5.1

Tackle is a declarative DSL for building modular workflows and code generators. Tool is plugins based and can easily be extended by writing additional hooks or importing external providers that can be turned into a self documenting CLI, all out of yaml, json, toml.

tackle

• Documentation
• Discord
• PyPI
• BSD License

Tackle is an experimental general purpose configuration language for building modular code generators and declarative CLIs. Built as a fork of cookiecutter, it can make any config file into a CLI with both strong and weakly typed programmable flow control common to a general purpose programming language. Basically you can write a fully functional Turing-complete program out of a config file. It's wild.

With tackle, you can build:

• Modular code generators / repo scaffolding tools that can be updated over time
• Interactive glue code for infrastructure-as-code deployment strategies
• Generic utilities like SSH helpers and dotfile managers
• Combinations of all of the above and anything else you can think of

If this project gets enough adoption / stars, it will be re-written in a compiled language, either Go or Rust. Give it a star if you'd like to see that.

Features

• Makes arbitrary yaml / json / toml dynamic
  • Embed loops, conditionals, and other custom logic
  • Self documenting CLI to call logic
• Ships with a collection of over 100 hooks that act like plugins within your config file
  • Prompt user for inputs
  • Generate code from templates
  • Read and write yaml / toml / json files
  • Make http calls
  • Run arbitrary system commands
  • Manipulate the context
  • Run other tackle files
• Modular design allows creating / importing new hooks easy
  • Supports both python and declarative hooks which can be imported / called / defined in-line or within jinja templates
  • Hooks can be composed of other hooks allowing complex objects to be validated and operated against

Install

Note: tackle can install dependencies on its own. Check docs for advanced installation methods to isolate tackle from your system python.

python -m venv env && source env/bin/activate
pip install tackle

Quick Demo: tackle sudoblockio/tackle-hello-world

Hello world

Check out the docs for >10 hello worlds that demonstrate the various aspects of the syntax with the simplest one using the print hook, one of >100 hooks.

hello.yaml

# Any time a key ends with `->`, we are calling a hook
hw->: print Hello world!

To run, call tackle hello.yaml. Can also be version controlled -> tackle sudoblockio/tackle-hello-world.

Can also use loops, conditionals, and other base methods.

hello.yaml

the:
  words:
    - Hello
    - cruel
    - world!
one liner->: print {{item}} --for the.words --if "item != 'cruel'"
multiple lines:
  ->: print
  objects: {{item}}
  for:
    - Hello
    - world!
  if: item != 'cruel'
# Or combinations of the above with other methods like try/except

New hooks can be made in python which under the hood is a pydantic model.

.hooks/hello.py

from tackle import BaseHook

class Greeter(BaseHook):
    hook_type: str = "greeter"
    target: str
    args: list = ['target']
    def exec(self):
      expression = f"Hello {self.target}"
      print(expression)
      return expression

Or can be defined inline within your tackle file, imported remotely, or in a hooks directory..

.hooks/hello.yaml

# Keys ending with `<-` mean we are creating a hook / method
greeter<-:
  target: str
  args: ['target']
  exec<-:
    expression->: var Hello {{target}}  # var hook renders variables
    p->: print {{expression}}
  return: expression

And both can be called the same way.

tackle.yaml

hello: world!
With a flag->: greeter --target {{hello}}
Target in argument->: greeter {{hello}}
Expanded fields:
  ->: greeter
  target: {{hello}}
Jinja template->: {{ greeter(hello) }}
# Or combinations jinja and compact / expanded hooks allowing chaining of hook calls.

With the declarative hooks being callable from the command line:

tackle hello.yaml greeter --target world!
# Or from a github repo
tackle sudoblockio/tackle-hello-world greeter --target world!

Documentation can be embedded into the hooks.

hello.yaml

<-:
  help: This is the default hook
  target:
    type: union[str, int]
    default->: input
    description: The thing to say hello to
  exec<-:
    greeting->: select Who to greet? --choices ['world',target]
    hi->: greeter --target {{greeting}}
  greeting-method<-:
    help: A method that greets
    # ... Greeting options / logic
    extends: greeter
greeter<-:
  help: A reusable greeter object
  target: str
  exec<-:
    hi->: print Hello {{target}}

Which when running tackle hello.yaml help produces its own help screen.

usage: tackle hello.yaml [--target]

This is the default hook

options:
    --target [str] The thing to say hello to
methods:
    greeting-method     A method that greets
    greeter     A reusable greeter object

Hooks can be imported within a tackle provider or through hooks, linked, and/or combined with inheritance or composition creating a web of CLIs.

Use Cases

• Code Generation

WIP Tutorials

• Declarative Utilities
• Infrastructure-as-Code Management
• Kubernetes Manifest Management
• Toolchain Management

Topics

• Writing Tackle Files
• Creating Providers
• Python Hooks
• Declarative Hooks
• Blocks and Flow Control
• Memory Management
• Special Variables
• Declarative CLIs

Known Issues

• Windows Support
  • tackle is lacking some windows support as shown in the failed tests. If you are a windows user, it is highly recommended to use WSL. Please get in touch if you are motivated to fix these tests to make tackle fully cross-platform. It probably isn't that hard to fix them as they mostly are due to differences in how windows handles paths.
• Whitespaces
  • tackle relies heavily on parsing based on whitespaces which if you are not careful can easily bite you. Whenever you need to have some whitespaces preserved, make sure to quote the entire expression. Future work will be put in to overhaul the regex based parser with a PEG parser like parsimonious.

Contributing

Contributions are welcome but please be advised of the following notes.

• This project uses conventional commits which generates the changelog with release-please-action in the release CI workflow. If commits have been made outside of this convention they will be squashed accordingly.
• For making changes to providers, please include test coverage using the existing fixtures and patterns from prior tests or communicate any suggestions that deviate from this style. It definitely can be improved but consistency is more important than making directed improvements. Tests should be runnable from the test's directory and via make test.
• For making changes to the core parser, please create a proposal first outlining your suggestions with examples before spending time working on code.

It is very easy to create new providers / hooks with tackle. Over time, it will adopt the same import pattern of what Ansible does where all provider / hooks (modules) are stored in version controlled locations. In the meantime, please feel free to contribute to this repository for hooks that have general applicability or create your own hooks in other repositories that are more bespoke / opinionated in nature.

Code of Conduct

Everyone interacting in the tackle project's codebases, issue trackers, chat rooms, and mailing lists is expected to follow the PyPA Code of Conduct.

Credit

Special thanks to the cookiecutter community for laying the basis for this project.