Note – instructions assume Ubuntu Linux.<\/p>\n
See Getting Started with Python on Heroku (Flask)<\/a> for the official instructions. The instructions below tackle things differently and include redis-specific steps. <\/p>\n Don’t need postgresql for my app even though needed for heroku demo app. Using redis for simple key-value store.<\/p>\n Main reason for each step is indicated in bold at start. There are lots of steps but there are lots of things being achieved. And each purpose only requires a few steps so probably hard to streamline any further. <\/p>\n So requirements for specific project can be separated from other project – lets heroku identify actual requirements. Normally “workon sticky” thereafter; deactivate to exit virtual env<\/li>\n Make a toy app to get started from.<\/p>\n Note – modify the standard demo flask app to add a port to ease eventual heroku deployment. Otherwise the app will fail because of a problem with the port when running <\/p>\n Here is an example (may need updating if flask changes):<\/p>\n @app.route(\"\/\") if __name__ == \"__main__\": url = urllib.parse.urlparse(os.environ.get('REDISTOGO_URL', Before deploying to production:<\/p>\n server { location \/static { # static content is location \/ { # all else passed to Gunicorn to handle bind = \"127.0.0.1:8888\" # ensure nginx passes to this port Should now be able to browse to the url supplied as stdout fom command e.g. >> git push heroku master<\/p>\n Must then actually spin up the app:<\/p>\n >> heroku ps:scale web=1<\/p>\n A shortcut for opening is<\/p>\n >> heroku open\n<\/li>\n Note – need to register credit card to use any add-ons, even if free ones. Go to https:\/\/heroku.com\/verify<\/a>\n<\/li>\n<\/ol>\n Some other points: when developing on a different machine, I needed to supply my public key to heroku from that other machine (Permission denied (publickey) when deploying heroku code. fatal: The remote end hung up unexpectedly<\/a>).<\/p>\n And the full sequence for upgrading your app after the prerequisites have been fulfilled is:<\/p>\n And I had a problem when I switched from Python 2 to 3 with redis – my heroku push wouldn’t work. By looking at the logs (>> heroku logs –tail) I found that import imap wouldn’t work and searching on that generally found I needed a newer version of redis than I had specified foolishly in requirements.txt.<\/p>\n","protected":false},"excerpt":{"rendered":" Note – instructions assume Ubuntu Linux. See Getting Started with Python on Heroku (Flask) for the official instructions. The instructions below tackle things differently and include redis-specific steps. Don’t need postgresql for my app even though needed for heroku demo … Continue reading \n
\n>> sudo apt-get install python3 python3-pip python-virtualenv git ruby redis-server redis-tools<\/li>\n
\nGet free heroku account<\/li>\n
\nInstall heroku toolbelt Heroku setup<\/a>. Sets up virtualenvwrapper for you too (one less thing to figure out)<\/li>\n
\nDo the once-ever authentication
\n>> heroku login<\/li>\n
\nMake project folder e.g.
\n>> mkdir ~\/projects\/myproj<\/li>\n
\n>> cd ~\/projects\/myproj<\/li>\n
\n>> echo “web: python main.py” > Procfile<\/li>\n
\n>> git init<\/li>\n
\n>> mkvirtualenv sticky<\/p>\n
\n>> pip3 install flask
\nNote – installed within virtualenv<\/li>\n
\nSave the following as requirements.txt – needed by heroku so it knows the dependencies. Update version of redis as appropriate. gunicorn is a better approach than the flask test server
\nflask
\ngunicorn
\nredis==2.10.3
\n<\/code>\n<\/li>\n
\nSo we can use Python 3.4 instead of the current default of 2.7:
\n>> echo “python-3.4.3” > runtime.txt\n<\/li>\nheroku ps:scale web=1<\/code><\/p>\nStarting process with command `python main.py`
\n...
\nWeb process failed to bind to $PORT within 60 seconds of launch<\/code><\/p>\nimport os
\nfrom flask import Flask
\napp = Flask(__name__)<\/p>\n
\ndef hello():
\n return \"Hello World!\"<\/p>\n
\n port = int(os.environ.get(\"PORT\", 33507))
\n app.run(host='0.0.0.0', port=port)<\/code>\n<\/li>\n
\n>> deactivate<\/li>\n
\n
\nimport os
\nimport urllib
\nimport redis<\/p>\n
\n 'redis:\/\/localhost:6379'))
\nredis = redis.Redis(host=url.hostname, port=url.port, db=0,
\n password=url.password)
\n<\/code>
\nWe can then use redis like this:
\nfrom store import redis<\/code>\n<\/li>\n
\nKeep building app locally. The following is good for redis: Redis docs<\/a>. And flasks docs are always good: Flask Docs – Minimal Application<\/a><\/li>\n\n
\nweb: gunicorn main:app --workers $WEB_CONCURRENCY<\/code>
\n)<\/li>\n
\n
\n# As long as \/etc\/nginx\/sites-enable\/ points to
\n# this conf file nginx can use it to work with
\n# the server_name defined (the name of the file
\n# doesn't matter - only the server_name setting)
\n# sudo ln -s \/home\/vagrant\/src\/nginx.conf ...
\n# ... \/etc\/nginx\/sites-enabled\/myproj.com
\n# Confirm this link is correct
\n# e.g. less \/etc\/nginx\/sites-enabled\/myproj.com<\/p>\n
\n listen 80;
\n server_name localhost;<\/p>\n
\n
# handled directly by NGINX which means
\n # the nginx user (www-data) will need
\n # read permissions to this folder
root \/home\/vagrant\/src;
\n
}<\/p>\n
\n # Pass to wherever I bind Gunicorn to serve to
\n # Only gunicorn needs rights to read, write,
\n # and execute scripts in the app folders
\n proxy_pass http:\/\/127.0.0.1:8888;
\n }
\n}
\n<\/code>\n<\/li>\n
\nimport multiprocessing<\/p>\n
\nlogfile = \"\/home\/vagrant\/gunicorn.log\"
\nworkers = multiprocessing.cpu_count() * 2 + 1
\n<\/code>\n<\/li>\n<\/ol>\n<\/li>\n
\n>> heroku create<\/p>\n
\nhttps:\/\/not-real-1234.herokuapp.com\/. Note – not working yet – still need to deploy to new app<\/p>\n
\nAdd redis support (after first deployment – otherwise
\n
\n ! No app specified.
\n ! Run this command from an app folder or specify which app to use with --app APP.
\n<\/code>)
\n>> heroku addons:create redistogo<\/p>\nheroku keys:add ~\/.ssh\/id_rsa.pub<\/code><\/p>\n\n
heroku ps:scale web=1<\/code> again<\/li>\n<\/ol>\n