Python Flask

%%python --bg

from flask import Flask, jsonify
from flask_cors import CORS

# initialize a flask application (app)
app = Flask(__name__)
CORS(app, supports_credentials=True, origins='*')  # Allow all origins (*)

# ... your existing Flask

# add an api endpoint to flask app
@app.route('/api/data')
def get_data():
    # start a list, to be used like a information database
    InfoDb = []

    # add a row to list, an Info record
    InfoDb.append({
        "FirstName": "John",
        "LastName": "Mortensen",
        "DOB": "October 21",
        "Residence": "San Diego",
        "Email": "jmortensen@powayusd.com",
        "Owns_Cars": ["2015-Fusion", "2011-Ranger", "2003-Excursion", "1997-F350", "1969-Cadillac"]
    })

    # add a row to list, an Info record
    InfoDb.append({
        "FirstName": "Shane",
        "LastName": "Lopez",
        "DOB": "February 27",
        "Residence": "San Diego",
        "Email": "slopez@powayusd.com",
        "Owns_Cars": ["2021-Insight"]
    })
    
    return jsonify(InfoDb)

# add an HTML endpoint to flask app
@app.route('/')
def say_hello():
    html_content = """
    <html>
    <head>
        <title>Hellox</title>
    </head>
    <body>
        <h2>Hello, World!</h2>
    </body>
    </html>
    """
    return html_content

if __name__ == '__main__':
    # starts flask server on default port, http://127.0.0.1:5001
    app.run(port=5001)

%%script bash

# After app.run(), see the the Python process
lsof -i :5001
# see the the Python app
lsof -i :5001 | awk '/Python/ {print $2}' | xargs ps

    PID TTY          TIME CMD
pts/0    00:00:00 sh
pts/0    00:00:00 sh
pts/0    00:00:00 sh
pts/0    00:00:05 node
pts/0    00:00:01 node
pts/0    00:00:31 node
pts/0    00:00:01 node
pts/0    00:00:02 node
pts/0    00:00:03 node
pts/0    00:00:00 node
pts/0    00:00:00 node
pts/0    00:00:00 node
pts/0    00:00:00 python
pts/0    00:00:28 node
pts/0    00:00:00 node
pts/0    00:00:01 python
pts/0    00:00:00 python
pts/0    00:00:00 bash
pts/0    00:00:00 xargs
pts/0    00:00:00 ps


your 131072x1 screen size is bogus. expect trouble

import requests
res = requests.get('http://127.0.0.1:5001/api/data')
res.json()

---------------------------------------------------------------------------

ConnectionRefusedError                    Traceback (most recent call last)

~/.local/lib/python3.10/site-packages/urllib3/connection.py in _new_conn(self)
    202         try:
--> 203             sock = connection.create_connection(
    204                 (self._dns_host, self.port),


~/.local/lib/python3.10/site-packages/urllib3/util/connection.py in create_connection(address, timeout, source_address, socket_options)
     84         try:
---> 85             raise err
     86         finally:


~/.local/lib/python3.10/site-packages/urllib3/util/connection.py in create_connection(address, timeout, source_address, socket_options)
     72                 sock.bind(source_address)
---> 73             sock.connect(sa)
     74             # Break explicitly a reference cycle


ConnectionRefusedError: [Errno 111] Connection refused


The above exception was the direct cause of the following exception:


NewConnectionError                        Traceback (most recent call last)

~/.local/lib/python3.10/site-packages/urllib3/connectionpool.py in urlopen(self, method, url, body, headers, retries, redirect, assert_same_host, timeout, pool_timeout, release_conn, chunked, body_pos, preload_content, decode_content, **response_kw)
    789             # Make the request on the HTTPConnection object
--> 790             response = self._make_request(
    791                 conn,


~/.local/lib/python3.10/site-packages/urllib3/connectionpool.py in _make_request(self, conn, method, url, body, headers, retries, timeout, chunked, response_conn, preload_content, decode_content, enforce_content_length)
    495         try:
--> 496             conn.request(
    497                 method,


~/.local/lib/python3.10/site-packages/urllib3/connection.py in request(self, method, url, body, headers, chunked, preload_content, decode_content, enforce_content_length)
    394             self.putheader(header, value)
--> 395         self.endheaders()
    396 


/usr/lib/python3.10/http/client.py in endheaders(self, message_body, encode_chunked)
   1277             raise CannotSendHeader()
-> 1278         self._send_output(message_body, encode_chunked=encode_chunked)
   1279 


/usr/lib/python3.10/http/client.py in _send_output(self, message_body, encode_chunked)
   1037         del self._buffer[:]
-> 1038         self.send(msg)
   1039 


/usr/lib/python3.10/http/client.py in send(self, data)
    975             if self.auto_open:
--> 976                 self.connect()
    977             else:


~/.local/lib/python3.10/site-packages/urllib3/connection.py in connect(self)
    242     def connect(self) -> None:
--> 243         self.sock = self._new_conn()
    244         if self._tunnel_host:


~/.local/lib/python3.10/site-packages/urllib3/connection.py in _new_conn(self)
    217         except OSError as e:
--> 218             raise NewConnectionError(
    219                 self, f"Failed to establish a new connection: {e}"


NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7ff2f9ec9b70>: Failed to establish a new connection: [Errno 111] Connection refused


The above exception was the direct cause of the following exception:


MaxRetryError                             Traceback (most recent call last)

~/.local/lib/python3.10/site-packages/requests/adapters.py in send(self, request, stream, timeout, verify, cert, proxies)
    485         try:
--> 486             resp = conn.urlopen(
    487                 method=request.method,


~/.local/lib/python3.10/site-packages/urllib3/connectionpool.py in urlopen(self, method, url, body, headers, retries, redirect, assert_same_host, timeout, pool_timeout, release_conn, chunked, body_pos, preload_content, decode_content, **response_kw)
    843 
--> 844             retries = retries.increment(
    845                 method, url, error=new_e, _pool=self, _stacktrace=sys.exc_info()[2]


~/.local/lib/python3.10/site-packages/urllib3/util/retry.py in increment(self, method, url, response, error, _pool, _stacktrace)
    514             reason = error or ResponseError(cause)
--> 515             raise MaxRetryError(_pool, url, reason) from reason  # type: ignore[arg-type]
    516 


MaxRetryError: HTTPConnectionPool(host='127.0.0.1', port=5001): Max retries exceeded with url: /api/data (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7ff2f9ec9b70>: Failed to establish a new connection: [Errno 111] Connection refused'))


During handling of the above exception, another exception occurred:


ConnectionError                           Traceback (most recent call last)

/tmp/ipykernel_4457/2595936190.py in <module>
      1 import requests
----> 2 res = requests.get('http://127.0.0.1:5001/api/data')
      3 res.json()


~/.local/lib/python3.10/site-packages/requests/api.py in get(url, params, **kwargs)
     71     """
     72 
---> 73     return request("get", url, params=params, **kwargs)
     74 
     75 


~/.local/lib/python3.10/site-packages/requests/api.py in request(method, url, **kwargs)
     57     # cases, and look like a memory leak in others.
     58     with sessions.Session() as session:
---> 59         return session.request(method=method, url=url, **kwargs)
     60 
     61 


~/.local/lib/python3.10/site-packages/requests/sessions.py in request(self, method, url, params, data, headers, cookies, files, auth, timeout, allow_redirects, proxies, hooks, stream, verify, cert, json)
    587         }
    588         send_kwargs.update(settings)
--> 589         resp = self.send(prep, **send_kwargs)
    590 
    591         return resp


~/.local/lib/python3.10/site-packages/requests/sessions.py in send(self, request, **kwargs)
    701 
    702         # Send the request
--> 703         r = adapter.send(request, **kwargs)
    704 
    705         # Total elapsed time of the request (approximately)


~/.local/lib/python3.10/site-packages/requests/adapters.py in send(self, request, stream, timeout, verify, cert, proxies)
    517                 raise SSLError(e, request=request)
    518 
--> 519             raise ConnectionError(e, request=request)
    520 
    521         except ClosedPoolError as e:


ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=5001): Max retries exceeded with url: /api/data (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7ff2f9ec9b70>: Failed to establish a new connection: [Errno 111] Connection refused'))

%%script bash

lsof -i :5001 | awk '/Python/ {print $2}' | xargs kill -9

Usage:
 kill [options] <pid> [...]

Options:
 <pid> [...]            send signal to every <pid> listed
 -<signal>, -s, --signal <signal>
                        specify the <signal> to be sent
 -q, --queue <value>    integer value to be sent with the signal
 -l, --list=[<signal>]  list all signal names, or convert one to a name
 -L, --table            list all signal names in a nice table

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see kill(1).



---------------------------------------------------------------------------

CalledProcessError                        Traceback (most recent call last)

/tmp/ipykernel_4457/1398621644.py in <module>
----> 1 get_ipython().run_cell_magic('script', 'bash', "\nlsof -i :5001 | awk '/Python/ {print $2}' | xargs kill -9\n")


/usr/lib/python3/dist-packages/IPython/core/interactiveshell.py in run_cell_magic(self, magic_name, line, cell)
   2417             with self.builtin_trap:
   2418                 args = (magic_arg_s, cell)
-> 2419                 result = fn(*args, **kwargs)
   2420             return result
   2421 


<decorator-gen-103> in shebang(self, line, cell)


/usr/lib/python3/dist-packages/IPython/core/magic.py in <lambda>(f, *a, **k)
    185     # but it's overkill for just that one bit of state.
    186     def magic_deco(arg):
--> 187         call = lambda f, *a, **k: f(*a, **k)
    188 
    189         if callable(arg):


/usr/lib/python3/dist-packages/IPython/core/magics/script.py in shebang(self, line, cell)
    243             sys.stderr.flush()
    244         if args.raise_error and p.returncode!=0:
--> 245             raise CalledProcessError(p.returncode, cell, output=out, stderr=err)
    246 
    247     def _run_script(self, p, cell, to_close):


CalledProcessError: Command 'b"\nlsof -i :5001 | awk '/Python/ {print $2}' | xargs kill -9\n"' returned non-zero exit status 123.

Python Flask • 17 min read

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