flexlate

Overview

Flexlate is a composable, maintainable system for managing project and file generator templates.

Update your projects generated from cookiecutter and copier and compose projects from multiple templates.

Features

• Update template outputs after there are changes to the template
  • When there is a conflict, it creates a Git merge conflict so that you can resolve it with your favorite tooling
  • It keeps a history of the conflict resolution so you are not resolving the same conflicts repeatedly
  • Use pre-built Github Actions to automatically get a PR in your project after the template has been updated
• Compose a project with multiple templates
  • Add template sources and then you can apply outputs anywhere with a simple CLI command
• Use your existing templates: both cookiecutter and copier templates are supported
  • Works with both local and remote templates. You can even keep a template in your project and be able to update outputs whenever it changes
• Apply it to your existing projects with a bootstrap functionality
• Update your projects automatically on CI with official Github Actions
• (planned) Use flexlate projects as templates themselves, enabling nested templates and sharing data across templates
• (planned) Allow multiple templates to coordinate on specific files in arbitrary ways, e.g. think about applying a template and it adds its required packages to package.json in a JS project

Use Cases

• You want to create or already have projects that are generated from a cookiecutter or copier template, and keep those projects up to date with changes in the template
• You want to create a project from standard building blocks that can also be updated systematically. For example think of something like a React component with tests, a Java class and tests, or any set of files you want to generate

Locally or Remote With a Team

In either case, you can use Flexlate 100% locally even on a team project without anyone else knowing you are using it via the user mode.

But Flexlate really shines when you embrace it fully and include it in your remote repo. This enables you use CI to automatically open PRs with template updates and merge Flexlate branches.

Why Flexlate?

Flexlate is born out of frustration with using project generator templates. You generate your project from a template, but later update the template and need to bring the changes back to your project. There are only a few tools for this and they do not have a great developer experience. Flexlate is Git-native, so you resolve template conflicts in Git as you would any other merge conflicts.

Further, there is not really any ability to compose a project template from smaller templates with any existing tools.

Check out a much more detailed explanation and story as well as a comparison to other tools.

How does it Work?

Flexlate is Git-native: it carries out all its operations via commits to Git branches. It maintains two branches, one that contains the history of the template output and the other than contains the merged output between your project and the template. This means that you resolve any conflicts with the template changes in Git and the merge conflict resolution is stored in the output branch.

It enables composability by using config files to keep track of where multiple templates should be rendered and with what data.

Learn more about Flexlate core concepts here.

Getting Started

Documentation

Visit the documentation for more detail on getting started. Start by learning about Flexlate core concepts before reading the user guide, which contains more detailed information on getting started.

Or, you can keep reading this high-level overview for abbreviated getting started steps.

Installing

Flexlate is a Python package that includes the fxt command line utility. If you do not have Python, you will need to install it first (required version is >=3.8).

The recommended way to install Flexlate is with pipx, though it can also be installed with pip.

pipx install flexlate

Or, if you don't have/don't want to install pipx:

pip install flexlate

Before using Flexlate, you will also need to have Git installed.

See the install guide for more information.

First Steps

Your first steps will depend on what you are trying to accomplish. See the "Next Steps" section of the installing guide for more information.

New Project from a Template

To generate a new project from a template, use init-from, e.g.:

fxt init-from https://github.com/nickderobertis/copier-pypi-sphinx-flexlate

See the user guide on creating a new project for more information.

Existing Project from a Template

To add Flexlate to your project that is already generated from a cookiecutter or cruft template, use bootstrap, e.g.:

fxt bootstrap https://github.com/nickderobertis/copier-pypi-sphinx-flexlate

See the user guide on adding Flexlate to an existing project from a template for more information.

Compose a Project from Multiple Templates

You can add a template source and then add as many outputs from that source as you want.

Before you can do this, you must initialize a Flexlate project:

fxt init

Then you can add the template source:

fxt add source https://github.com/nickderobertis/copier-pypi-sphinx-flexlate

Then you can apply the output anywhere in the project:

fxt add output copier-pypi-sphinx-flexlate

See the user guide on adding templates within an existing project for more information.

Updating a Template

See the user guide on updating a template for more information, but here's some quick info.

Re-prompt Questions

Once you have updates in the template that you want to bring to your project, use the update command:

fxt update

This will prompt for all the questions again, using your previous answers as defaults. If there are new questions from the update, or if you want to change any of the answers, you should follow this flow.

No Question Prompts

If instead you know that there are only changes in the outputs and not questions/answers, you can pass --no-input or -n to skip the questions:

fxt update -n

Saving your Work

See the user guide on saving Flexlate updates for more information, but here's some quick info.

Local Repo Flows

If you are following a local repo flow, then you can use the fxt merge command to merge the Flexlate feature branches into the Flexlate main branches. If you are using a feature-branch flow, then you would want to run fxt merge just before merging your feature branch into the main branch. If you are simply commititng to the main branch, just run fxt merge after any Flexlate command.

Remote Repo/PR Flows

If you are merging PRs in your repo rather than following a local flow, then you will want to fxt push feature just before/after your push your feature branch and open a PR. If you use the official Flexlate Github Merge Action, the Flexlate branches will be merged automatically after the PR is merged.

Get Help

You can run --help on the end of any command to see documentation. You will see similar output to what is in the command reference.

$ fxt --help
Usage: fxt [OPTIONS] COMMAND [ARGS]...

  fxt is a CLI tool to manage project and file generator templates.

  [See the Flexlate documentation](
  https://nickderobertis.github.io/flexlate/ ) for more information.

Options:
  -v, --version         Show Flexlate version and exit
  --install-completion  Install completion for the current shell.
  --show-completion     Show completion for the current shell, to copy it or
                        customize the installation.

  --help                Show this message and exit.

Commands:
  add        Add template sources and generate new projects and files from...
  bootstrap  Sets up a Flexlate project from an existing project that was...
  check      Checks whether there are any updates available for the current...
  config     Modify Flexlate configs via CLI
  init       Initializes a flexlate project.
  init-from  Generates a project from a template and sets it up as a...
  merge      Merges feature flexlate branches into the main flexlate...
  push       Push Flexlate branches to remote repositories.
  remove     Remove template sources and previously generated outputs
  sync       Syncs manual changes to the flexlate branches, and updates...
  undo       Undoes the last flexlate operation, like ctrl/cmd + z for...
  update     Updates applied templates in the project to the newest
             versions...

Please raise an issue if anything is confusing or does not work properly.

See a more in-depth tutorial here.

Development Status

This project is currently in early-stage development. There may be breaking changes often. While the major version is 0, minor version upgrades will often have breaking changes.

Developing

First ensure that you have pipx installed, if not, install it with pip install pipx.

Then clone the repo and run npm install and pipenv sync. Run pipenv shell to use the virtual environment. Make your changes and then run nox to run formatting, linting, and tests.

Develop documentation by running nox -s docs to start up a dev server.

To run tests only, run nox -s test. You can pass additional arguments to pytest by adding them after --, e.g. nox -s test -- -k test_something.

Author

Created by Nick DeRobertis. MIT License.

Links

See the documentation here.