This challenge provides the basic framework for creating web-challenges that run as a flask server.
In addition to the challenge description in problem.json, challenge authors
need to provide the flask app with the main entry file named as app.py.
There are three values that cmgr will template into app.py: {{flag}},
{{secret_key}}, and {{seed}}. These values are provided to minimize the
need for boilerplate code that challenge authors need. If there is a need for
random values beyond the flag and Flask's secret key for session cookies,
challenge authors should ensure they use {{seed}} as the initial seed for
Python's random library in order to ensure reproducible builds.
NOTE: Because both Flask and cmgr use Jinja2-style formatting
directives, cmgr only templates app.py to avoid trampling any
formatting directives intended for the Flask application itself.
There are two means for installing additional dependencies that the challenge
requires: packages.txt for apt packages and requirements.txt for pip3
modules. Both files consist of a single dependency per line. Note: although
requirements.txt supports pinning the version of each dependency, there is
currently no support for similar functionality in packages.txt.