I have set up a flask application to use uwsgi and nginx
I used the tutorials on the internet but I have the following issue
I have the following functions on the controller.py file
api_module = Blueprint('cassandra_api', __name__, url_prefix="/api")
#api_module.route('/', methods=['GET', 'POST'])
def home():
return "c"
the above works great when trying
myip/api/
but the following doesn't work at all
#api_module.route("/fault_prone_snippets/", methods=['GET'])
def get_fault_prone_snippets():
#code to connect with cassandra db and retrieve get parameters
When I visit
myip/api/faut_prone_snippets/
with or without get parameters, no code is executed, I don't see an error message and after the minute is over I get a gateway timeout. The problem is that when I run my flask from localhost it works great. Trying to use cassandra driver from the python console on my dev environment works too and connects with no error. How can I debug this kind of setup when it works locally but not in production?
As you're running behind nginx it might be that setting the keep_alive timeout in the http section of your nginx.conf will help. And/or proxy_send_timeout,
proxy_read_timeout parameters in the location section.
Related
I'm trying to create a simple flask server that redirects any http requests to https. I've created a certificate and key file and registered a before_request hook to see if the request is secure and redirect appropriately, following advise this SO answer.
The flask server responds to https requests as expected. However, when I send an http request, the before_request hook never gets called and ther server hangs forever. If I send the http request from the browser, I see an "ERR_EMPTY_RESPONSE". The server doesn't even respond to https requests afterwards. No logs are printed either.
Running the app with gunicorn didn't help either. The only difference was that gunicorn is able to detect that the worker is frozen and eventually kills and replaces it. I've also tried using flask-talisman, with the same results.
Below is the code I'm running
### server.py
from flask import Flask, request, redirect
def verify_https():
if not request.is_secure:
url = request.url.replace("http://", "https://", 1)
return redirect(url, 301)
def create_flask_app():
app = Flask(__name__)
app.before_request(verify_https)
app.add_url_rule('/', 'root', lambda: "Hello World")
return app
if __name__ == '__main__':
app = create_flask_app()
app.run(
host="0.0.0.0",
port=5000,
ssl_context=('server.crt', 'server.key')
)
Running it with either python3.8 server.py or gunicorn --keyfile 'server.key' --certfile 'server.crt' --bind '0.0.0.0:5000' 'server:create_flask_app()' and opening a browser window to localhost:5000 causes the server to hang.
Talking about freezes, its not. Flask and gunicorn can serve only one variant of connection. So it's not freezing because your browser canceled the request and is idling.
I think it is better to use a faster web server, for example, Nginx, if you want to change HTTP to HTTPS. I would recommend it to you.
But it's possible to trigger your verify_https function if you run multiple instances of gunicorn at the same time.
I took your example, generated a certificate, and then run this script in my console (it contains a background job and can be runned in twoo separate ter)
gunicorn --bind '0.0.0.0:80' 'server:create_flask_app()' & gunicorn --certfile server.crt --keyfile server.key --bind '0.0.0.0:443' 'server:create_flask_app()'
now chrome goes to the secure page as expected.
Typically servers don't listen for both http and https on the same port. I have a similar requirement for my personal portfolio, but I use nginx to forward http requests (port 80) to https (port 443) and then the https server passes it off to my uwsgi backend, which listens on port 3031. That's probably more complex than you need, but a possible solution. If you go that route I would recommend letsencrypt for your certificate needs. It will set up the certificates AND the nginx.conf for you.
If you don't want to go the full nginx/apache route I think your easiest solution is the one suggested here on that same thread that you linked.
I'm new to python and flask, I'm following this tutorial to create an application with flask and angular.
To make things quicker, because I don't need a database at the moment, I skipped the steps of creating the model and the connection.
I ran this command touch src/__init__.py and in my myapp/backend/src/main.py I have this:
from flask import Flask, jsonify, request
app = Flask(__name__)
#app.route('/test')
def get_exams():
print('ou')
if __name__ == '__main__':
app.run(host='0.0.0.0',port=5000)
Also I created the myapp/backend/bootstrap.sh with this:
#!/bin/bash
export FLASK_APP=./src/main.py
source $(pipenv --venv)/bin/activate
flask run -h 0.0.0.0
But if I try to run curl http://0.0.0.0:5000/test I got this error curl: (7) Failed to connect to 0.0.0.0 port 5000: Address not available
Aside from the database steps, I made everything according to the tutorial.
You need named the route to the method exams /test.
So you need to call /test not /exams
curl http://0.0.0.0:5000/test
The route defines the URI/URL and calls the method associated with it. The names are totally independent and completely up to you. So you are very fine to also name the route /exams as well.
I have a dash(plotly) app set up using flask as the server and can serve it on our Windows Server to port:8041 using waitress. My code to launch waitress is below;
#!/usr/bin/env python3
from waitress import serve
from src.pacedash.app import server as application
if __name__ == "__main__":
serve(application, threads=100, port=8041)
Everything works great if I use python run_waitress.py, except that when someone on our network navigates to the servename:8041 there is a "Not Secure" warning next to the url. Our IT vendor was able to get a cert file and key, but I'm not sure how to bring those into my current setup.
I have been trying to use nginx, but I can't find a guide to setting it up with waitress and I'm not too familiar with web apps or wsgi because I primarily work as the lone data person here.
I have been working on this same issue and have a solution. The nginx .conf file needs have a location defined like this:
location /myapp/ {
# Define the location of the proxy server to send the request to
proxy_pass http://localhost:8041/myapp/;
# standard proxy_set_header stuff below...
}
Then in your Dash application set the url_base_pathname to the same value:
app = dash.Dash(__name__, url_base_pathname='/myapp/')
I would use ngrok to expose your web app. It's amazingly simple:
Read this: https://ngrok.com/
I could be misinterpreting what you need, because I am not familiar with waitress (why not serve the app locally just using flask?), but if you need to test the live app, ngrok is what you should use.
I have managed to to install flask and run the hello-world script:
from flask import Flask
app = Flask(__name__)
#app.route('/')
def hello_world():
return 'Hello World!'
if __name__ == '__main__':
app.run()
I was impressed how easy it was. Then I wanted to make my web-server visible externally. As recommended, I put host='0.0.0.0' as the argument of run function. Then I found my IP address (in Google) and put it in the address line of my web browser (while the hello-world-script was running).
As a result I got: "A username and password are being requested" and a dialogue box where I need to put a user name and password. I am not sure but I think it comes from my wireless network. Is there a way to change this behaviour?
How are you trying to run your application? If you run flask as app.run() - flask creates its own WSGI server on your host (by default 127.0.0.1) and port (by default 5000) (need permissions if port < 1000). If you run flask using nginx + WSGI or etc. your server resolves host and port.
Now it looks like you want get application by port which resolved your server like nginx or Apache. Try to get flask application by http://your-server-host-or-ip:5000 with the default port or try to change the port (set explicit) like app.run('0.0.0.0', 8080) and get it by http://your-server-host-or-ip:8080.
By the way, you can always get IP address using command-line tools e.g. ifconfig for Unix-like systems, or ipconfig /all for Windows.
To elaborate a little bit onto what #tbicr said, that password prompt indicates that you're trying to connect to your IP on port 80, which is most likely hosting an administration page for your router/modem. You want to connect to your IP on port 5000, the default port for Flask apps run with app.run().
I have a linux box (Ubuntu 10.10 server edition) in ec2. I have written a web service using cherrypy framework. Let's say this is the code that I have written.
import sys
sys.path.insert(0,'cherrypy.zip')
import cherrypy
from cherrypy import expose
class Service:
#expose
def index(self):
return 'Hello World'
cherrypy.quickstart(Service())
I have copied this file, the cherrypy.zip file to /var/www in my ec2 instance. [I should inform that I created the www directory manually, as it wasn't there]. Then I ran
python webservice.py
and got the message
[01/Apr/2011:13:50:04] ENGINE Bus STARTED
However, when I try to run
(I have masked my public ip)
ec2-1**-2**-1**-**.ap-southeast-1.compute.amazonaws.com/
in my browser, I get connection failed. Can anyone tell me where I have gone wrong? or what I should do?
EDIT:
Okay, here is something interesting that I found. When I do
python webservice.py
I see
ENGINE Serving on 127.0.0.1:8080
Which means, the webservice will run only for the local machine. How do I make set the service 0.0.0.0 (that is, to serve any IP address?)
Hope this detail is sufficient for understanding the problem I'm facing. Help, please :)
EDIT 2:
Oh well, found the solution :-) Have to add this before cherrypy.quickstart() call
cherrypy.config.update({'server.socket_host': '0.0.0.0',
'server.socket_port': 80,
})
The cherrypy.quickstart function takes a config argument, which can be a dict, an open configuration file, or a path to a configuration file. I favor using a path to a configuration file because that minimizes the hardcoding of settings that you might prefer to control from a startup script.
In addition, since you control the server, you could configure a reverse proxy to route requests to the CherryPy application. This gives you quite a bit of flexibility. For example, if you wanted to, you could run multiple instances of the CherryPy application in parallel, each configured to listen on a different port.
Here's a sample configuration file for nginx, instructing it to forward requests to a single instance of your CherryPy application:
server
{
server_name your.hostname.com;
location / {
proxy_pass http://127.0.0.1:8080/;
}
}
And here's a sample configuration file instructing nginx to load-balance across two instances of your application, which are listening on the loopback address at ports 33334 and 33335:
upstream myapps {
server 127.0.0.1:33334;
server 127.0.0.1:33335;
}
server {
server_name your.hostname.com;
location / {
proxy_pass http://myapps;
}
}