Grip -- GitHub Readme Instant Preview

Render local readme files before sending off to GitHub.

Grip is a command-line server application written in Python that uses the GitHub markdown API to render a local readme file. The styles also come directly from GitHub, so you'll know exactly how it will appear.

Motivation

Sometimes you just want to see the exact readme result before committing and pushing to GitHub.

Especially when doing Readme-driven development.

Installation

To install grip, simply:

$ pip install grip

Usage

To render the readme of a repository:

$ cd myrepo
$ grip
 * Running on http://localhost:6419/

Now open a browser and visit http://localhost:6419.

You can also specify a port:

$ grip 80
 * Running on http://localhost:80/

Or an explicit file:

$ grip AUTHORS.md
 * Running on http://localhost:6419/

Alternatively, you could just run grip and visit localhost:6419/AUTHORS.md since grip supports relative URLs.

You can combine the previous examples. Or specify a hostname instead of a port. Or provide both.

$ grip AUTHORS.md 80
 * Running on http://localhost:80/

$ grip CHANGES.md 0.0.0.0
 * Running on http://0.0.0.0:6419/

$ grip . 0.0.0.0:80
 * Running on http://0.0.0.0:80/

You can even bypass the server and export to a single HTML file, with all the styles and assets inlined:

$ grip --export
Exporting to README.html

Control the output name with the second argument:

$ grip README.md --export readme.html
Exporting to readme.html

Reading and writing from stdin and stdout is also supported, allowing you to use Grip with other programs:

$ cat README.md | grip -
 * Running on http://localhost:6419/

$ grip AUTHORS.md --export - | bcat

$ cat README.md | grip --export - | less

This allows you to quickly test how things look by entering Markdown directly in your terminal:

$ grip -
Hello **world**!
^D
 * Running on http://localhost:6419/

Note: ^D means Ctrl+D, which works on Linux and iOS. On Windows you'll have to use Ctrl+Z.

Comment / issue-style GFM is also supported, with an optional repository context for linking to issues:

$ grip --gfm --context=joeyespo/grip
 * Running on http://localhost:6419/

For more details and additional options, see the help:

$ grip -h

Access

Grip strives to be as close to GitHub as possible. To accomplish this, grip uses GitHub's Markdown API so that changes to their rendering engine are reflected immediately without requiring you to upgrade grip. However, because of this you may hit the API's hourly rate limit. If this happens, grip offers a way to access the API using your credentials to unlock a much higher rate limit.

$ grip --user <your-username> --pass <your-password>

Or use a personal access token with an empty scope (note that a token is required if your GitHub account is set up with two-factor authentication):

$ grip --pass <token>

You can persist these options in your local configuration. For security purposes, it's highly recommended that you use an access token over a password. (You could also keep your password safe by configuring Grip to grab your password from a password manager.)

There's also a work-in-progress branch to provide offline rendering. Once this resembles GitHub more precisely, it'll be exposed in the CLI, and will ultimately be used as a seamless fallback engine for when the API can't be accessed.

Grip always accesses GitHub over HTTPS, so your README and credentials are protected.

Known issues

GitHub introduced read-only task lists to all Markdown documents in repositories and wikis back in April, but the API doesn't respect this yet.

Configuration

To customize Grip, create ~/.grip/settings.py, then add one or more of the following variables:

HOST: The host to use when not provided as a CLI argument, localhost by default
PORT: The port to use when not provided as a CLI argument, 6419 by default
DEBUG: Whether to use Flask's debugger when an error happens, True by default
DEBUG_GRIP: Prints extended information when an error happens, False by default
USERNAME: The username to use when not provided as a CLI argument, None by default
PASSWORD: The password or personal access token to use when not provided as a CLI argument (Please don't save your passwords here. Instead, use an access token or drop in this code grab your password from a password manager), None by default
API_URL: Base URL for the github API, for example that of a Github Enterprise instance. The default is the public API https://api.github.com.
CACHE_DIRECTORY: The directory, relative to ~/.grip, to place cached assets (this gets run through the following filter: CACHE_DIRECTORY.format(version=__version__)), 'cache-{version}' by default
CACHE_URL: The URL to serve cached styles and assets from, in case there's a URL conflict, '/grip-cache' by default
STATIC_URL_PATH: The URL to serve static assets from, in case there's a URL conflict, '/grip-static' by default
STYLE_URLS: Additional URLs that will be added to the rendered page, [] by default
STYLE_URLS_SOURCE: The URL to use to locate and download the styles from, https://github.com/joeyespo/grip by default
STYLE_URLS_RE: The regular expression to use to parse the styles from the source
STYLE_ASSET_URLS_RE: The regular expression to use to parse the assets from the styles
STYLE_ASSET_URLS_SUB: Replaces the above regular expression with a local URL, as saved in the cache
STYLE_ASSET_URLS_INLINE: The regular expression to use when inlining assets into the downloaded style Note that this must include both the original and post-STYLE_ASSET_URLS_SUB patterns.

Advanced

This file is a normal Python script, so you can add more advanced configuration.

For example, to read a setting from the environment and provide a default value when it's not set:

PORT = os.environ.get('GRIP_PORT', 8080)

API

You can access the API directly with Python, using it in your own projects:

from grip import serve

serve(port=8080)
 * Running on http://localhost:8080/

Or access the underlying Flask application for even more flexibility:

from grip import create_app

grip_app = create_app(gfm=True)
# Use in your own app

Documentation

serve

Runs a local server and renders the Readme file located at path when visited in the browser.

serve(path=None, host=None, port=None, gfm=False, context=None, username=None, password=None, render_offline=False, render_wide=False, render_inline=False, api_url=None, title=None)

path: The filename to render, or the directory containing your Readme file, defaulting to the current working directory
host: The host to listen on, defaulting to the HOST configuration variable
port: The port to listen on, defaulting to the PORT configuration variable
gfm: Whether to render using GitHub Flavored Markdown
context: The project context to use when gfm is true, which takes the form of username/project
username: The user to authenticate with GitHub to extend the API limit
password: The password to authenticate with GitHub to extend the API limit
render_offline: Whether to render locally using Python-Markdown (Note: this is a work in progress)
render_wide: Whether to render a wide page, False by default (this has no effect when used with gfm)
render_inline: Whether to inline the styles within the HTML file
api_url: A different base URL for the github API, for example that of a Github Enterprise instance. The default is the public API https://api.github.com.
title: The page title, derived from path by default

export

Writes the specified Readme file to an HTML file with styles and assets inlined.

export(path=None, gfm=False, context=None, username=None, password=None, render_offline=False, render_wide=False, render_inline=True, out_filename=None, api_url=None, title=None)

path: The filename to render, or the directory containing your Readme file, defaulting to the current working directory
gfm: Whether to render using GitHub Flavored Markdown
context: The project context to use when gfm is true, which takes the form of username/project
username: The user to authenticate with GitHub to extend the API limit
password: The password to authenticate with GitHub to extend the API limit
render_offline: Whether to render locally using Python-Markdown (Note: this is a work in progress)
render_wide: Whether to render a wide page, False by default (this has no effect when used with gfm)
render_inline: Whether to inline the styles within the HTML file (Note: unlike the other API functions, this defaults to True)
out_filename: The filename to write to, <in_filename>.html by default
api_url: A different base URL for the github API, for example that of a Github Enterprise instance. The default is the public API https://api.github.com.
title: The page title, derived from path by default

create_app

Creates a Flask application you can use to render and serve the Readme files. This is the same app used by serve and export and initializes the cache, using the cached styles when available.

create_app(path=None, gfm=False, context=None, username=None, password=None, render_offline=False, render_wide=False, render_inline=False, api_url=None, title=None, text=None)

path: The filename to render, or the directory containing your Readme file, defaulting to the current working directory
gfm: Whether to render using GitHub Flavored Markdown
context: The project context to use when gfm is true, which takes the form of username/project
username: The user to authenticate with GitHub to extend the API limit
password: The password to authenticate with GitHub to extend the API limit
render_offline: Whether to render locally using Python-Markdown (Note: this is a work in progress)
render_wide: Whether to render a wide page, False by default (this has no effect when used with gfm)
render_inline: Whether to inline the styles within the HTML file
api_url: A different base URL for the github API, for example that of a Github Enterprise instance. The default is the public API https://api.github.com.
title: The page title, derived from path by default
text: A string or stream of Markdown text to render instead of being loaded from path (Note: path can be used to set the page title)

render_app

Renders the application created by create_app and returns the HTML that would normally appear when visiting that route.

render_app(app, route='/')

app: The Flask application to render
route: The route to render, '/' by default

render_content

Renders the specified markdown text without caching.

render_content(text, gfm=False, context=None, username=None, password=None, render_offline=False, api_url=None, title=None)

text: The Markdown text to render
gfm: Whether to render using GitHub Flavored Markdown
context: The project context to use when gfm is true, which takes the form of username/project
username: The user to authenticate with GitHub to extend the API limit
password: The password to authenticate with GitHub to extend the API limit
render_offline: Whether to render locally using Python-Markdown (Note: this is a work in progress)
api_url: A different base URL for the github API, for example that of a Github Enterprise instance. This is required when not using the offline renderer.
title: The page title, derived from path by default

render_page

Renders the markdown from the specified path or text, without caching, and returns an HTML page that resembles the GitHub Readme view.

render_page(path=None, gfm=False, context=None, username=None, password=None, render_offline=False, render_wide=False, render_inline=False, api_url=None, title=None, text=None)

path: The path to use for the page title, rendering 'README.md' if None
gfm: Whether to render using GitHub Flavored Markdown
context: The project context to use when gfm is true, which takes the form of username/project
username: The user to authenticate with GitHub to extend the API limit
password: The password to authenticate with GitHub to extend the API limit
render_offline: Whether to render offline using Python-Markdown (Note: this is a work in progress)
render_wide: Whether to render a wide page, False by default (this has no effect when used with gfm)
render_inline: Whether to inline the styles within the HTML file
api_url: A different base URL for the github API, for example that of a Github Enterprise instance. The default is the public API https://api.github.com.
title: The page title, derived from path by default
text: A string or stream of Markdown text to render instead of being loaded from path (Note: path can be used to set the page title)

resolve_readme

Returns the path if it's a file; otherwise, looks for a compatible README file in the directory specified by path. If path is None, the current working directory is used. If no compatible README can be found, ValueError is raised.

resolve_readme(path=None, force=False)

path: The filename to render, or the directory containing your Readme file, defaulting to the current working directory
force: Whether to force a result, even when a readme file is not found

clear_cache

Clears the cached styles and assets.

clear_cache()

supported_extensions

The supported extensions, as defined by GitHub.

supported_extensions = ['.md', '.markdown']

default_filenames

This constant contains the names Grip looks for when no file is provided.

default_filenames = map(lambda ext: 'README' + ext, supported_extensions)

Contributing

Check the open issues or open a new issue to start a discussion around your feature idea or the bug you found
Fork the repository, make your changes, and add yourself to Authors.md
Send a pull request

If your PR has been waiting a while, feel free to ping me on Twitter.

Use this software often? Please consider supporting me on

TJ56/grip