Docker/Web Noob trying to get a Flask MongoDB app to work with a Meinheld-Gunicorn-Flask Docker image

I found this: https://github.com/tiangolo/meinheld-gunicorn-flask-docker after multiple failed attempts to follow along various tutorials on the web to containerize my app to build a CI pipeline. My app:https://github.com/nyck33/canadian-nutrient-file

When I forked that app, it used bin/cnf runserver as the command to run but I refactored cnf/main.py to run as `python cnf/main.py" to work with the tiangolo image mentioned above.

Here is my docker-compose.yml

version: '3'services:  flask:    environment:      CNF_MONGO_HOST: mongo://db:27017      MODULE_NAME: cnf.main    build: . #build from dockerfile    ports:      - "8888:8888"  db:    image: mongo:3.6.3    ports:      - "27017:27017"    command: bash -c "sudo service mongodb start"

and the Dockerfile:

FROM tiangolo/meinheld-gunicorn-flask:python3.7COPY . /appCOPY /cnf_csv /app/cnf_csvRUN python3 bootstrap.py && \    bin/buildout

So I'm hoping the mongo container starts up and starts listening on port 27017 for connections since that is what is designated in my settings.py which looks like:

import osimport datetimefrom urllib.parse import urljoinROOT_PATH = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))class Config:    APP_NAME = "cnf"    APP_SYSTEM_ERROR_SUBJECT_LINE = APP_NAME +"system error"    #Flask Settings    CSRF_ENABLES = True    # for host url, set env variables with export    FLASK_BIND = os.getenv('CNF_BIND', 'localhost')    FLASK_PORT = int(os.getenv('CNF_PORT', 8888))    ROOT_URL = 'http://'+ FLASK_BIND +':'+ str(FLASK_PORT) +'/'    TEMPLATE_FOLDER = os.path.join(ROOT_PATH, 'cnf', 'templates')    STATIC_FOLDER = os.path.join(ROOT_PATH, 'cnf', 'static')    #encryption, cryptographically signs client-side cookies so they cannot be tampered with    #if tampered, session becomes invalid, insecure not to be used production    SECRET_KEY = 'this key is not secure so be careful until it is'    WTF_CSRF_SECRET_KEY = 'this key may or may not be secure so change it'    # Flask-User Settings    # from https://flask-user.readthedocs.io/en/latest/configuring_settings.html    USER_APP_NAME = "cnf"    USER_ENABLE_EMAIL = False  # register with email    USER_ENABLE_CONFIRM_EMAIL = False # force users to confirm email    USER_ENABLE_USERNAME = True  # enable username authentication    USER_REQUIRE_RETYPE_PASSWORD = False  # simplify register form    USER_EMAIL_SENDER_NAME = 'nobu'    #USER_EMAIL_SENDER_EMAIL = 'nobu.kim66@gmail.com' # set up Flask Mail for this    USER_ENABLE_CHANGE_USERNAME = True    USER_ENABLE_CHANGE_PASSWORD = True    USER_ENABLE_FORGOT_PASSWORD = True    #USER_ENABLE_REGISTER = True    USER_ENABLE_REGISTRATION = True    USER_ENABLE_REMEMBER_ME = True    USER_AFTER_LOGIN_ENDPOINT = 'main.member_page'    USER_AFTER_LOGOUT_ENDPOINT = 'main.home_page'    # Flask-Mail settings    # For smtp.gmail.com to work, you MUST set "Allow less secure apps" to ON in Google Accounts.    # Change it in https://myaccount.google.com/security#connectedapps (near the bottom).    MAIL_SERVER = 'smtp.gmail.com'    MAIL_PORT = 587    MAIL_USE_SSL = False    MAIL_USE_TLS = True    #MAIL_USERNAME = gmail_credentials[0]    #MAIL_PASSWORD = gmail_credentials[1]    MAIL_USERNAME = "-----"    MAIL_PASSWORD = "-----"    #ADMINS = ['"Admin One" <admin@gmail.com>,]    # Sendgrid settings    #SENDGRID_API_KEY='place-your-sendgrid-api-key-here'class DevelopmentConfig(Config):    MONGODB_HOST = os.getenv('CNF_MONGO_HOST', 'localhost')    # for docker:    #MONGODB_HOST = 'db'    MONGODB_PORT = int(os.getenv('CNF_MONGO_PORT', 27017))    # Todo: should get a dev_cnf db    MONGODB_DB = os.getenv('CNF_MONGO_DB', 'cnf')    # configuration from env variables, 12 factor cnf documentation    DEBUG = (os.getenv('CNF_DEBUG', 'True') == 'True')    FLASK_DEBUG = DEBUGclass TestingConfig(Config):    MONGODB_HOST = os.getenv('CNF_MONGO_HOST', 'localhost')    #for docker:    #MONGODB_HOST = 'db'    MONGODB_PORT = int(os.getenv('CNF_MONGO_PORT', 27017))    MONGODB_DB = os.getenv('CNF_MONGO_DB', 'cnf_test')  # name of db    TESTING = (os.getenv('CNF_TESTING', 'True') == 'True')class ProductionConfig(Config):    MONGODB_HOST = os.getenv('CNF_MONGO_HOST', 'localhost')    MONGODB_PORT = int(os.getenv('CNF_MONGO_PORT', 27017))    # Todo: should get a dev_cnf db    MONGODB_DB = os.getenv('CNF_MONGO_DB', 'cnf')config = {'development': DevelopmentConfig,'testing': TestingConfig,'production': ProductionConfig,'default': DevelopmentConfig}

Output from docker-compose build

(gamechangers) nobu@gold3forever:~/Desktop/comp4911/Project/canadian-nutrient-file$ docker-compose builddb uses an image, skippingBuilding flaskStep 1/4 : FROM tiangolo/meinheld-gunicorn-flask:python3.7 ---> 8c21eb2c0391Step 2/4 : COPY . /app ---> a34b3105f2caStep 3/4 : COPY /cnf_csv /app/cnf_csv ---> 87d4d818dbd5Step 4/4 : RUN python3 bootstrap.py &&     bin/buildout ---> Running in eb2d6784975eez_setup.py is deprecated and when using it setuptools will be pinned to 33.1.1 since it's the last version that supports setuptools self upgrade/installation, check https://github.com/pypa/setuptools/issues/581 for more info; use pip to install setuptoolsDownloading https://pypi.io/packages/source/s/setuptools/setuptools-33.1.1.zipExtracting in /tmp/tmpgbjf27wbNow working in /tmp/tmpgbjf27wb/setuptools-33.1.1Building a Setuptools egg in /tmp/tmp609izx6gwarning: no files found matching '*' under directory 'setuptools/_vendor'/tmp/tmp609izx6g/setuptools-33.1.1-py3.7.eggno previously-included directories found matching 'doc'no previously-included directories found matching 'old-tutorial'Creating directory '/app/develop-eggs'.Generated script '/app/bin/buildout'./tmp/tmp609izx6g/setuptools-33.1.1-py3.7.egg/pkg_resources/__init__.py:184: RuntimeWarning: You have iterated over the result of pkg_resources.parse_version. This is a legacy behavior which is inconsistent with the new version class introduced in setuptools 8.0. In most cases, conversion to a tuple is unnecessary. For comparison of versions, sort the Version instances directly. If you have another use case requiring the tuple, please file a bug with the setuptools project describing that need.Develop: '/app/.'Getting distribution for 'zc.recipe.egg==2.0.3'.WARNING: The easy_install command is deprecated and will be removed in a future version.Got zc.recipe.egg 2.0.3.Uninstalling eggs.Installing eggs.Generated script '/app/bin/cnf'.Generated interpreter '/app/bin/python'.Removing intermediate container eb2d6784975e ---> 35ed375967ffSuccessfully built 35ed375967ffSuccessfully tagged cnf_flask:latest

And docker-compose up -d

(gamechangers) nobu@gold3forever:~/Desktop/comp4911/Project/canadian-nutrient-file$ docker-compose up -dCreating cnf_db_1    ... doneCreating cnf_flask_1 ... done(gamechangers) nobu@gold3forever:~/Desktop/comp4911/Project/canadian-nutrient-file$ docker-compose up -dStarting cnf_db_1    ... doneStarting cnf_flask_1 ... done(gamechangers) nobu@gold3forever:~/Desktop/comp4911/Project/canadian-nutrient-file$ docker-compose up -dStarting cnf_db_1    ... doneStarting cnf_flask_1 ... done(gamechangers) nobu@gold3forever:~/Desktop/comp4911/Project/canadian-nutrient-file$ docker psCONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

So it looks like the containers start but stop immediately.

Any hints are welcome and appreciated.