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Helper module for Frozen-Flask based websites

Project description


Elsa will help you build your Frozen-Flask based website and deploy it to GitHub pages. It’s based on scripts from repo and is distributed under the terms of the MIT license, see LICENSE (does not apply for the image below). It requires Python 3.


Basic usage

Create you Flask app and give it to elsa.cli():

from flask import Flask

app = Flask(...)

# do stuff with app

if __name__ == '__main__':
    from elsa import cli
    cli(app, base_url='')

This will add command line interface to the script, enabling you to use it like this:

python serve  # serves the site, no freezing, so you can check it quickly
python freeze  # freezes the site, i.e. makes a HTML snapshot
python deploy  # deploys the frozen site to GitHub pages

See more options with --help.

Follow the quickstart tutorial for more information.

Travis CI based deployment

Travis CI is (in this context) a tool, that allows you to deploy the site automatically to GitHub pages after every push. All you have to do is tell Travis to run Elsa and provide a GitHub token. Elsa on Travis will freeze the site and deploy it frozen to GitHub pages. Elsa knows it’s being run on Travis and will use the provided GitHub token to gain push permissions. Elsa will push force to gh-pages branch in a single commit rewriting the history and all manual changes of that branch.

Here is an example .travis.yml file for automatic deployment. It assumes elsa and other requirements are in requirements.txt and that you are familiar with Travis CI (so it’s not very verbose):

language: python
    - '3.6'
    - 'python freeze'
    - secure: "blahblah"  # gem install travis; travis encrypt GITHUB_TOKEN=xyz --add
    provider: script
    skip_cleanup: true
    script: 'python deploy --no-freeze --push'
        branch: master
        repo: only/yours


To run the test suite, install tox and run it:


Elsa uses pytest, so if you are familiar with it, feel free to run it directly.

Further notes


When you use URLs without trailing slash (e.g., GitHub pages would serve the pages with bad Content-Type header (application/octet-stream instead of text/html) and the browser would attempt to download it. That’s why Elsa will not allow such thing and will treat MimetypeMismatchWarning from Frozen-Flask as error. Make sure to use URLs with trailing slash (e.g. instead, so Frozen-Flask will create index.html in a folder and GitHub pages will use proper content type.



  • Add the --host option to CLI. It corresponds to flask run’s --host option.
  • When serving (with serve or freeze --serve), Elsa now listens on Flask’s default address, The server is not visible externally. Use --host= to select the original, less secure behavior. (#67)


  • Add --verbose option for the CLI. If used, it prints all frozen URLs to standard error. Useful when freezing big projects on Travis CI. (#51)


  • Add invoke_cli option for the cli function. If set to False, it only returns the cli for further extending. (#45)
  • Don’t remove the remote tracking branch when --no-push is used (fixes #41)
  • Improve handling of FrozenFlaskWarning (#37)
  • Add the --show-git-push-stderr option to make deploy more verbose, this can help debug problems, but is potentially dangerous, hence the output of git push is hidden by default. (#37)


  • Only treat Frozen-Flask warnings as errors, not other warnings (#34)
  • Add a --remote option for deploy to use a custom git remote
  • Be consistent on local vs Travis CI deployment, always erase the history of the gh-pages branch (actually fixes #14)


  • Security: Do not display the remote URL when pushing gh-pages branch. If you used Elsa 0.1 or 0.1.1 on Travis CI, revoke your GitHub token, it was probably leaked in the log. (#25)


  • Fix a problem with Travis CI based deployment


  • Add a test suite
  • Treat Frozen-Flask warnings as errors
  • Important: It is now recommended to run freeze in .travis.yml script section to catch problems in Pull Requests etc.
  • Important: This version of Elsa will warn if you use the deploy command without specifying --push or --no-push explicitly. In a future release, it will switch to not pushing the built pages by default.
  • Remove the dependency on sh to improve compatibility with Windows
  • Supports Linux, Mac OS X and Windows
  • The gh-branch is purged before the deploying commit (#14)
  • It is possible to shutdown the server via a special POST request (#21)


  • Set template auto_reload flag directly in serve mode (#8)


  • Set TEMPLATES_AUTO_RELOAD by default (#5)
  • Suppress a bogus warning about CNAME mime type (#7)


  • The CNAME route is now created automatically


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