python:dev-mode [N99panel Documentation]

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===Using Python in Development Mode===

It involves two aspects - launching the app from SSH console, and then linking to the the VHost/Website URL end point. Lets go step by step on it.

**Step 1 :** Log into N99panel. From under N99panel dashboard, click 'List Users'

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**Step 2 :** You will see the list of all the users. Please click 'Manage SSHD/CronD' link against the appropriate user

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**Step 3 :** Now choose 'Full SSHD mode with Python'. With this you get the maximum command set which includes **python3** and **pip3** binaries along with git and other useful command set.

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When you click 'Submit', upon successful job execution, the SSHD daemon would restart, and its host signature would change from what it was earlier. This implies that when you try to connect via SSH, you will get a warning for the same, and that you need to appropriately handle at your end.

**Step 4 :** SSH using to the VPS using the above user's credentials

**Step 5 :** Change over to directory/folder //python_apps// . If it is not created, please create it manually. //python_apps// folder is also used when you have to later launch your app in production mode

Assuming you are /home///user// folder, please run the below command to create python_apps folder, if it does not exist.

<code>
mkdir python_apps
</code>

Now change into python_apps folder

<code>
cd python_apps
</code>

**Step 6 :** From within this folder add/create your python project as you would normally do. Below we illustrate with specific examples for Flask, Django and Generic modes

**Flask**

<code>
mkdir flask-project
cd flask-project
python3 -m venv .venv
source .venv/bin/activate
</code>

Running the last command with activate the virtual environment, proceeding further

<code>
pip install flask
pip install gunicorn
</code>

You you can upload/write your Flask app and fire it up using gunicorn, but here I will showcase an example using the hello world app - refer https://flask.palletsprojects.com/en/2.3.x/quickstart/ 

Below code is saved to hello.py

<code>
from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello_world():
    return "<p>Hello, World!</p>"
</code>

Now to fire our flash app, we use gunicorn 

<code>
gunicorn -b 0.0.0.0:8000 -w 4 --forwarded-allow-ips='172.16.26.1' hello:app
</code>

To run it in background, we append & to the above command

<code>
gunicorn -b 0.0.0.0:8000 -w 4 --forwarded-allow-ips='172.16.26.1' hello:app &
</code>

To exit virtual environment use the command
<code>
deactivate
</code>

**Django**

<code>
mkdir django-project
cd django-project
python3 -m venv .venv
source .venv/bin/activate
</code>

Running the last command with activate the virtual environment, proceeding further

<code>
pip install django
pip install gunicorn
</code>

Here we can refer to https://docs.djangoproject.com/en/5.1/intro/tutorial01/ to run a hello world Django application

<code>
django-admin startproject mysite
cd mysite
</code>

When you change into //mysite// folder, it contains //manage.py// along with a //mysite// child folder

W.r.t. Django, please refer to these important links \\
* https://docs.djangoproject.com/en/1.10/ref/settings/#allowed-hosts - Please add your VHost name as mentioned in the linked article \\
* https://docs.djangoproject.com/en/3.0/ref/settings/#secure-proxy-ssl-header - Tt concerns the prefixing of http or https to your URLs/Assets

Now to fire our Django app, we use gunicorn 

<code>
gunicorn -b 0.0.0.0:8000 -w 4 --forwarded-allow-ips='172.16.26.1' mysite.wsgi
</code>

To run it in background, we append & to the above command

<code>
gunicorn -b 0.0.0.0:8000 -w 4 --forwarded-allow-ips='172.16.26.1' mysite.wsgi &
</code>


To exit virtual environment use the command
<code>
deactivate
</code>


**Generic Python App**

<code>
mkdir generic-project
cd geneic-project
python3 -m venv .venv
source .venv/bin/activate
</code>

Running the last command with activate the virtual environment, proceeding further

<code>
pip install gunicorn
</code>

Here is a small hello world example of our generic app

Below code is saved to hello.py

<code>
def app(environ, start_response):
    data = b"Hello, World!\n"
    start_response("200 OK", [
        ("Content-Type", "text/plain"),
        ("Content-Length", str(len(data)))
    ])
    return iter([data])
</code>

Now to fire our flash app, we use gunicorn 

<code>
gunicorn -b 0.0.0.0:8000 -w 4 --forwarded-allow-ips='172.16.26.1' hello:app
</code>

To run it in background, we append & to the above command

<code>
gunicorn -b 0.0.0.0:8000 -w 4 --forwarded-allow-ips='172.16.26.1' hello:app &
</code>

To exit virtual environment use the command
<code>
deactivate
</code>
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**With this our SSH Console aspect of our python project is covered. Now we will link our app to our VHost/Website URL**


**Step 6 :** Log into N99panel and click on 'Python'

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**Step 7 :** Now click on 'Python Apps via SSH'

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**Step 8 :** Now further click on 'Map a Python Dev Port'

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**Step 9 :** Fill the form with the requisite details

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With these above mentioned steps, you can showcase your python apps to the world very easily.