Related
I'm not sure if this is Flask specific, but when I run an app in dev mode (http://localhost:5000), I cannot access it from other machines on the network (with http://[dev-host-ip]:5000). With Rails in dev mode, for example, it works fine. I couldn't find any docs regarding the Flask dev server configuration. Any idea what should be configured to enable this?
While this is possible, you should not use the Flask dev server in production. The Flask dev server is not designed to be particularly secure, stable, or efficient. See the docs on deploying for correct solutions.
The --host option to flask run, or the host parameter to app.run(), controls what address the development server listens to. By default it runs on localhost, change it to flask run --host=0.0.0.0 (or app.run(host="0.0.0.0")) to run on all your machine's IP addresses.
0.0.0.0 is a special value that you can't use in the browser directly, you'll need to navigate to the actual IP address of the machine on the network. You may also need to adjust your firewall to allow external access to the port.
The Flask quickstart docs explain this in the "Externally Visible Server" section:
If you run the server you will notice that the server is only
accessible from your own computer, not from any other in the network.
This is the default because in debugging mode a user of the
application can execute arbitrary Python code on your computer.
If you have the debugger disabled or trust the users on your network,
you can make the server publicly available simply by adding
--host=0.0.0.0 to the command line:
$ flask run --host=0.0.0.0
This tells your operating system to listen on all public IPs.
If you use the flask executable to start your server, use flask run --host=0.0.0.0 to change the default from 127.0.0.1 and open it up to non-local connections.
If you run the server you will notice that the server is only
accessible from your own computer, not from any other in the network.
This is the default because in debugging mode a user of the
application can execute arbitrary Python code on your computer.
If you have the debugger disabled or trust the users on your network,
you can make the server publicly available simply by adding
--host=0.0.0.0 to the command line:
$ flask run --host=0.0.0.0
This tells your operating system to listen on all public IPs.
Reference: https://flask.palletsprojects.com/quickstart/
Try this if the 0.0.0.0 method doesn't work
Boring Stuff
I personally battled a lot to get my app accessible to other devices(laptops and mobile phones) through a local-server. I tried the 0.0.0.0 method, but no luck. Then I tried changing the port, but it just didn't work. So, after trying a bunch of different combinations, I arrived to this one, and it solved my problem of deploying my app on a local server.
Steps
Get the local IPv4 address of your computer.
This can be done by typing ipconfig on Windows and ifconfig on Linux
and Mac.
Please note: The above step is to be performed on the machine you are serving the app on, and on not the machine on which you are accessing it. Also note, that the IPv4 address might change if you disconnect and reconnect to the network.
Now, simply run the flask app with the acquired IPv4 address.
flask run -h 192.168.X.X
E.g. In my case (see the image), I ran it as:
flask run -h 192.168.1.100
On my mobile device
Optional Stuff
If you are performing this procedure on Windows and using Power Shell as the CLI, and you still aren't able to access the website, try a CTRL + C command in the shell that's running the app. Power Shell gets frozen up sometimes and it needs a pinch to revive. Doing this might even terminate the server, but it sometimes does the trick.
That's it. Give a thumbs up if you found this helpful.😉
Some more optional stuff
I have created a short Powershell script that will get you your IP address whenever you need one:
$env:getIp = ipconfig
if ($env:getIp -match '(IPv4[\sa-zA-Z.]+:\s[0-9.]+)') {
if ($matches[1] -match '([^a-z\s][\d]+[.\d]+)'){
$ipv4 = $matches[1]
}
}
echo $ipv4
Save it to a file with .ps1 extension (for PowerShell), and run it on before starting your app. You can save it in your project folder and run it as:
.\getIP.ps1; flask run -h $ipv4
Note: I saved the above shellcode in getIP.ps1.
Cool.👌
Add host='0.0.0.0' to app.run`.
if __name__ == '__main__':
app.run(host='0.0.0.0', port=5000)
If you get OSError: [WinError 10013] An attempt was made to access a socket in a way forbidden by its access permissions on Windows, you either don't have permission to use the port, or something else is using it which you can find with netstat -na|findstr 5000.
Check whether the particular port is open on the server to serve the client or not?
in Ubuntu or Linux distro
sudo ufw enable
sudo ufw allow 5000/tcp //allow the server to handle the request on port 5000
Configure the application to handle remote requests
app.run(host='0.0.0.0' , port=5000)
python3 app.py & #run application in background
If your cool app has it's configuration loaded from an external file, like in the following example, then don't forget to update the corresponding config file with HOST="0.0.0.0"
cool.app.run(
host=cool.app.config.get("HOST", "localhost"),
port=cool.app.config.get("PORT", 9000)
)
If you're having troubles accessing your Flask server, deployed using PyCharm, take the following into account:
PyCharm doesn't run your main .py file directly, so any code in if __name__ == '__main__': won't be executed, and any changes (like app.run(host='0.0.0.0', port=5000)) won't take effect.
Instead, you should configure the Flask server using Run Configurations, in particular, placing --host 0.0.0.0 --port 5000 into Additional options field.
More about configuring Flask server in PyCharm
You can also set the host (to expose it on a network facing IP address) and port via environment variables.
$ export FLASK_APP=app.py
$ export FLASK_ENV=development
$ export FLASK_RUN_PORT=8000
$ export FLASK_RUN_HOST=0.0.0.0
$ flask run
* Serving Flask app "app.py" (lazy loading)
* Environment: development
* Debug mode: on
* Running on https://0.0.0.0:8000/ (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 329-665-000
See How to get all available Command Options to set environment variables?
Go to your project path on CMD(command Prompt) and execute the following command:-
set FLASK_APP=ABC.py
SET FLASK_ENV=development
flask run -h [yourIP] -p 8080
you will get following o/p on CMD:-
Serving Flask app "expirement.py" (lazy loading)
Environment: development
Debug mode: on
Restarting with stat
Debugger is active!
Debugger PIN: 199-519-700
Running on http://[yourIP]:8080/ (Press CTRL+C to quit)
Now you can access your flask app on another machine using http://[yourIP]:8080/ url
For me i followed the above answer and modified it a bit:
Just grab your ipv4 address using ipconfig on command prompt
Go to the file in which flask code is present
In main function write app.run(host= 'your ipv4 address')
Eg:
Create file .flaskenv in the project root directory.
The parameters in this file are typically:
FLASK_APP=app.py
FLASK_ENV=development
FLASK_RUN_HOST=[dev-host-ip]
FLASK_RUN_PORT=5000
If you have a virtual environment, activate it and do a pip install python-dotenv .
This package is going to use the .flaskenv file, and declarations inside it will be automatically imported across terminal sessions.
Then you can do flask run
This answer is not solely related with flask, but should be applicable for all cannot connect service from another host issue.
use netstat -ano | grep <port> to see if the address is 0.0.0.0 or ::. If it is 127.0.0.1 then it is only for the local requests.
use tcpdump to see if any packet is missing. If it shows obvious imbalance, check routing rules by iptables.
Today I run my flask app as usual, but I noticed it cannot connect from other server. Then I run netstat -ano | grep <port>, and the local address is :: or 0.0.0.0 (I tried both, and I know 127.0.0.1 only allows connection from the local host). Then I used telnet host port, the result is like connect to .... This is very odd. Then I thought I would better check it with tcpdump -i any port <port> -w w.pcap. And I noticed it is all like this:
Then by checking iptables --list OUTPUT section, I could see several rules:
these rules forbid output tcp vital packets in handshaking. By deleting them, the problem is gone.
I had the same problem, I use PyCharm as an editor and when I created the project, PyCharm created a Flask Server. What I did was create a server with Python in the following way;
basically what I did was create a new server but flask if not python
I hope it helps you
This finally worked for me.
import os
Then place this at the end of your python app.py or main file.
if __name__ == "__main__":
port = int(os.environ.get("PORT", 5000))
app.run(host='0.0.0.0', port=port)
go to project path
set FLASK_APP=ABC.py
SET FLASK_ENV=development
flask run -h [yourIP] -p 8080
you will following o/p on CMD:-
* Serving Flask app "expirement.py" (lazy loading)
* Environment: development
* Debug mode: on
* Restarting with stat
* Debugger is active!
* Debugger PIN: 199-519-700
* Running on http://[yourIP]:8080/ (Press CTRL+C to quit)
If none of the above solutions are working, try manually adding "http://" to the beginning of the url.
Chrome can distinguish "[ip-address]:5000" from a search query. But sometimes that works for a while, and then stops connecting, seemingly without me changing anything. My hypothesis is that the browser might sometimes automatically prepend https:// (which it shouldn't, but this fixed it in my case).
In case you need to test your app from an external network.
Simply serve it to the whole Internet with ngrok.com
which will deploy it like a dev server but in no time and locally, saved me a lot of time, and no, I'm not related to that company :)
Just make sure to change the port in your flask app:
app.run(host='0.0.0.0', port=80)
Currently trying to run an h2o-wave app on a remote server. I'm restricted to using 0.0.0.0 as the host on the server (the specific port is not as restrictive).
I've looked at the h2o configuration documentation and tried several variations of what they suggest:
H2O_WAVE_INTERNAL_ADDRESS=ws://0.0.0.0:8000
H2O_WAVE_EXTERNAL_ADDRESS=ws://0.0.0.0:8000
H2O_WAVE_APP_ADDRESS=ws://0.0.0.0:8000
But, the app is still running on the default localhost: http://127.0.0.1:8000
Just setting H2O_WAVE_APP_ADDRESS is enough.
$ H2O_WAVE_APP_ADDRESS=http://0.0.0.0:8000 uvicorn my_app:main
I'm not sure if this is Flask specific, but when I run an app in dev mode (http://localhost:5000), I cannot access it from other machines on the network (with http://[dev-host-ip]:5000). With Rails in dev mode, for example, it works fine. I couldn't find any docs regarding the Flask dev server configuration. Any idea what should be configured to enable this?
While this is possible, you should not use the Flask dev server in production. The Flask dev server is not designed to be particularly secure, stable, or efficient. See the docs on deploying for correct solutions.
The --host option to flask run, or the host parameter to app.run(), controls what address the development server listens to. By default it runs on localhost, change it to flask run --host=0.0.0.0 (or app.run(host="0.0.0.0")) to run on all your machine's IP addresses.
0.0.0.0 is a special value that you can't use in the browser directly, you'll need to navigate to the actual IP address of the machine on the network. You may also need to adjust your firewall to allow external access to the port.
The Flask quickstart docs explain this in the "Externally Visible Server" section:
If you run the server you will notice that the server is only
accessible from your own computer, not from any other in the network.
This is the default because in debugging mode a user of the
application can execute arbitrary Python code on your computer.
If you have the debugger disabled or trust the users on your network,
you can make the server publicly available simply by adding
--host=0.0.0.0 to the command line:
$ flask run --host=0.0.0.0
This tells your operating system to listen on all public IPs.
If you use the flask executable to start your server, use flask run --host=0.0.0.0 to change the default from 127.0.0.1 and open it up to non-local connections.
If you run the server you will notice that the server is only
accessible from your own computer, not from any other in the network.
This is the default because in debugging mode a user of the
application can execute arbitrary Python code on your computer.
If you have the debugger disabled or trust the users on your network,
you can make the server publicly available simply by adding
--host=0.0.0.0 to the command line:
$ flask run --host=0.0.0.0
This tells your operating system to listen on all public IPs.
Reference: https://flask.palletsprojects.com/quickstart/
Try this if the 0.0.0.0 method doesn't work
Boring Stuff
I personally battled a lot to get my app accessible to other devices(laptops and mobile phones) through a local-server. I tried the 0.0.0.0 method, but no luck. Then I tried changing the port, but it just didn't work. So, after trying a bunch of different combinations, I arrived to this one, and it solved my problem of deploying my app on a local server.
Steps
Get the local IPv4 address of your computer.
This can be done by typing ipconfig on Windows and ifconfig on Linux
and Mac.
Please note: The above step is to be performed on the machine you are serving the app on, and on not the machine on which you are accessing it. Also note, that the IPv4 address might change if you disconnect and reconnect to the network.
Now, simply run the flask app with the acquired IPv4 address.
flask run -h 192.168.X.X
E.g. In my case (see the image), I ran it as:
flask run -h 192.168.1.100
On my mobile device
Optional Stuff
If you are performing this procedure on Windows and using Power Shell as the CLI, and you still aren't able to access the website, try a CTRL + C command in the shell that's running the app. Power Shell gets frozen up sometimes and it needs a pinch to revive. Doing this might even terminate the server, but it sometimes does the trick.
That's it. Give a thumbs up if you found this helpful.😉
Some more optional stuff
I have created a short Powershell script that will get you your IP address whenever you need one:
$env:getIp = ipconfig
if ($env:getIp -match '(IPv4[\sa-zA-Z.]+:\s[0-9.]+)') {
if ($matches[1] -match '([^a-z\s][\d]+[.\d]+)'){
$ipv4 = $matches[1]
}
}
echo $ipv4
Save it to a file with .ps1 extension (for PowerShell), and run it on before starting your app. You can save it in your project folder and run it as:
.\getIP.ps1; flask run -h $ipv4
Note: I saved the above shellcode in getIP.ps1.
Cool.👌
Add host='0.0.0.0' to app.run`.
if __name__ == '__main__':
app.run(host='0.0.0.0', port=5000)
If you get OSError: [WinError 10013] An attempt was made to access a socket in a way forbidden by its access permissions on Windows, you either don't have permission to use the port, or something else is using it which you can find with netstat -na|findstr 5000.
Check whether the particular port is open on the server to serve the client or not?
in Ubuntu or Linux distro
sudo ufw enable
sudo ufw allow 5000/tcp //allow the server to handle the request on port 5000
Configure the application to handle remote requests
app.run(host='0.0.0.0' , port=5000)
python3 app.py & #run application in background
If your cool app has it's configuration loaded from an external file, like in the following example, then don't forget to update the corresponding config file with HOST="0.0.0.0"
cool.app.run(
host=cool.app.config.get("HOST", "localhost"),
port=cool.app.config.get("PORT", 9000)
)
If you're having troubles accessing your Flask server, deployed using PyCharm, take the following into account:
PyCharm doesn't run your main .py file directly, so any code in if __name__ == '__main__': won't be executed, and any changes (like app.run(host='0.0.0.0', port=5000)) won't take effect.
Instead, you should configure the Flask server using Run Configurations, in particular, placing --host 0.0.0.0 --port 5000 into Additional options field.
More about configuring Flask server in PyCharm
You can also set the host (to expose it on a network facing IP address) and port via environment variables.
$ export FLASK_APP=app.py
$ export FLASK_ENV=development
$ export FLASK_RUN_PORT=8000
$ export FLASK_RUN_HOST=0.0.0.0
$ flask run
* Serving Flask app "app.py" (lazy loading)
* Environment: development
* Debug mode: on
* Running on https://0.0.0.0:8000/ (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 329-665-000
See How to get all available Command Options to set environment variables?
Go to your project path on CMD(command Prompt) and execute the following command:-
set FLASK_APP=ABC.py
SET FLASK_ENV=development
flask run -h [yourIP] -p 8080
you will get following o/p on CMD:-
Serving Flask app "expirement.py" (lazy loading)
Environment: development
Debug mode: on
Restarting with stat
Debugger is active!
Debugger PIN: 199-519-700
Running on http://[yourIP]:8080/ (Press CTRL+C to quit)
Now you can access your flask app on another machine using http://[yourIP]:8080/ url
For me i followed the above answer and modified it a bit:
Just grab your ipv4 address using ipconfig on command prompt
Go to the file in which flask code is present
In main function write app.run(host= 'your ipv4 address')
Eg:
Create file .flaskenv in the project root directory.
The parameters in this file are typically:
FLASK_APP=app.py
FLASK_ENV=development
FLASK_RUN_HOST=[dev-host-ip]
FLASK_RUN_PORT=5000
If you have a virtual environment, activate it and do a pip install python-dotenv .
This package is going to use the .flaskenv file, and declarations inside it will be automatically imported across terminal sessions.
Then you can do flask run
This answer is not solely related with flask, but should be applicable for all cannot connect service from another host issue.
use netstat -ano | grep <port> to see if the address is 0.0.0.0 or ::. If it is 127.0.0.1 then it is only for the local requests.
use tcpdump to see if any packet is missing. If it shows obvious imbalance, check routing rules by iptables.
Today I run my flask app as usual, but I noticed it cannot connect from other server. Then I run netstat -ano | grep <port>, and the local address is :: or 0.0.0.0 (I tried both, and I know 127.0.0.1 only allows connection from the local host). Then I used telnet host port, the result is like connect to .... This is very odd. Then I thought I would better check it with tcpdump -i any port <port> -w w.pcap. And I noticed it is all like this:
Then by checking iptables --list OUTPUT section, I could see several rules:
these rules forbid output tcp vital packets in handshaking. By deleting them, the problem is gone.
I had the same problem, I use PyCharm as an editor and when I created the project, PyCharm created a Flask Server. What I did was create a server with Python in the following way;
basically what I did was create a new server but flask if not python
I hope it helps you
This finally worked for me.
import os
Then place this at the end of your python app.py or main file.
if __name__ == "__main__":
port = int(os.environ.get("PORT", 5000))
app.run(host='0.0.0.0', port=port)
go to project path
set FLASK_APP=ABC.py
SET FLASK_ENV=development
flask run -h [yourIP] -p 8080
you will following o/p on CMD:-
* Serving Flask app "expirement.py" (lazy loading)
* Environment: development
* Debug mode: on
* Restarting with stat
* Debugger is active!
* Debugger PIN: 199-519-700
* Running on http://[yourIP]:8080/ (Press CTRL+C to quit)
If none of the above solutions are working, try manually adding "http://" to the beginning of the url.
Chrome can distinguish "[ip-address]:5000" from a search query. But sometimes that works for a while, and then stops connecting, seemingly without me changing anything. My hypothesis is that the browser might sometimes automatically prepend https:// (which it shouldn't, but this fixed it in my case).
In case you need to test your app from an external network.
Simply serve it to the whole Internet with ngrok.com
which will deploy it like a dev server but in no time and locally, saved me a lot of time, and no, I'm not related to that company :)
Just make sure to change the port in your flask app:
app.run(host='0.0.0.0', port=80)
I'm developing an app on Python using flask and I'm getting this error while trying to deploy it to Heroku:
Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
On the Heroku logs, I can see this line
Few possibilities that I have tried
In my Procfile I have written this web: python hello-mysql.py
I have also tried web: python hello-mysql.py runserver 0.0.0.0=$PORT
Replace "web" with "worker" in your Procfile.
To #damien's point, it looks like you're not binding to the $PORT env var. Here's some documentation that may help: https://devcenter.heroku.com/articles/getting-started-with-python#define-a-procfile and https://devcenter.heroku.com/articles/dynos#web-dynos
Also, do not rename your process to "worker" since only processes named web will be accessible via http/https.
Simply, use gunicorn to easen the burden.
Within the project directory, with the virtual environment activated, install gunicorn as follows:
pip install gunicorn
If you're using pipenv you can try:
pipenv install gunicorn
Update the requirements.txt file to include the new installed gunicorn module by running:
pip freeze > requirements.txt
Update the Procfile as follows:
web: gunicorn your_django_project_name.wsgi --log-file -
N.B:
There should be space between the web: and gunicorn as well as between --log-file and the - next to it.
Lastly, add, commit and push the changes
I'm trying to deploy a flask app on heroku. I've gotten to the point where the app builds and deploys, but when I try to go to the URL, the app times out with the following error.
Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
I think the problem is with my procfile. It has one line.
web: python add_entry3.py
Other people have procfiles that look like this:
web: gunicorn app:app
This is just a toy app and I don't care about performance so I don't think I need to use gunicorn for the web server. Should I be putting a colon and command after my app's file name (add_entry3.py)?
Most likely your flask app isn't answering on the port and interface the Heroku expects. By default, Flask only listens on 127.0.0.1, and I think on port 5000. Heroku passes your app a PORT environment variable and you'd need to tell Flask to listen on all interfaces.
But there are reasons other than performance you want to avoid Flask's default debug server for production code. It's got memory leaks, there are security implications, and really ... just don't do it. Add gunicorn to your requirements.txt and use that.
But if you must use the Flask test/debug server, change your app.run() call to something like this:
app.run(host='0.0.0.0', port=int(os.environ.get("PORT", 5000)))