Passenger running Flask site returning 500 error on Dreamhost

Question

I am having trouble getting Passenger to work with Flask. I am running the Flask site on DreamHost inside a virutalenv running Python 3.5.2. The application should receive input from a query string in the URL, parse a server-side JSON file, search the JSON file for said query string, reformat the JSON, and send it back to the client. Instead, it gives me the 500 error code. Here is my code. Please pardon all the logging function calls. I've done what I can by searching around.

import logging
logging.basicConfig(filename='wsgi_flask.log', level=logging.DEBUG)
try:
    import sys, os

    logging.info('line 7')

    VENV = os.path.join(os.environ['HOME'], '.pyenv', 'versions', '3.5.2', 'envs', 'flask')
    INTERP = os.path.join(VENV, 'bin', 'python')

    logging.info('line 12')

    if sys.executable != INTERP:
        os.execl(INTERP, INTERP, *sys.argv)

    logging.info('line 17')

    sys.path.append(VENV)
    sys.path.append(os.path.join(VENV, 'lib', 'python3.5', 'site-packages'))
    sys.path.append(os.path.join(os.environ['HOME'], 'api.example.com'))

    logging.info('line 23')

    # INTERP = os.path.join(os.environ['HOME'], '.pyenv', 'versions', 'flask', 'bin', 'python')
    # if sys.executable != INTERP:
    #     os.execl(INTERP, INTERP, *sys.argv)
    # sys.path.append(os.getcwd())
    from paste.exceptions.errormiddleware import ErrorMiddleware

    logging.info('line 31')

    # import argparse
    import json

    logging.info('line 36')

    from flask import (Flask, abort, g, jsonify, make_response, redirect,
                   render_template, render_template_string, request, url_for, Response)

    logging.info('line 41')

    # parser = argparse.ArgumentParser()
    # parser.add_argument('-d', '--debug', action='store_true')
    # apargs = parser.parse_args()

    # def debugLog(*args):
    #     if apargs.debug:
    #         for i in args:
    #             print(i)

    application = Flask(__name__)

    logging.info('line 54')

    @application.route('/')
    def index():
        logging.info('line 58')
        # if apargs.debug:
        #     data = json.load(open('/path/to/test.json', 'rb'))
        # else:
        logging.info('line 62')
        try:
            logging.info('line 64')
            data = json.load(open('/path/to/test.json', 'rb'))
            logging.info('line 66')
        except:
            logging.info('line 68')
            logging.warning('Is it the JSON?')
            raise('Error whilst loading JSON')
        logging.info('line 71')
        getForm = request.args.get('search') or ''
        logging.info('line 73')

        # debugLog(data, getForm)

        jsonData = ""
        logging.info('line 78')
        for d in data:
            logging.info('line 80 (for loop)')
            # debugLog(d)
            if getForm in d['text']:
                logging.info('line 83 (for loop)')
                jsonData = jsonData + str(d) + ','
                logging.info('line 85 (for loop)')
            logging.info('line 86 (for loop)')
        logging.info('line 87 (out of loop)')
        # debugLog(jsonData)

        jsonData = str(jsonData)
        logging.info('line 91')
        jsonData = jsonData[:-1]
        logging.info('line 93')
        jsonData = jsonData.replace("'", '"')
        logging.info('line 95')
        jsonData = '[' + jsonData + ']'
        logging.info('line 97')

        # debugLog('\n', jsonData)
        return Response(jsonify(json.loads(jsonData)), mimetype='application/json')
        logging.info('line 101 (this should not show)')

        @application.errorhandler(500)
        def error(e):
            logging.warning(e + '\n\n\n What\'s happening here')
            return str(e)
        logging.info('line 107')
        application = ErrorMiddleware(application, debug=True, error_log='tmp/wsgi_error.log')
        logging.info('line 109')

    # if apargs.debug:
    #     application.run(host='0.0.0.0', debug=True, port=80)
except:
    logging.warning('line 114 (beginning of outer most try-except)')
    import sys, os
    logging.warning('line 116')

    from traceback import format_list, extract_tb
    logging.warning('line 119')
    (extype, value, trace) = sys.exc_info()
    logging.warning('line 121')

    sys.stderr.buffer.write("%s:%s\n%s" % (extype, value,''.join(format_list(extract_tb(trace)))))
    logging.warning('line 124 (EOF)')

This is my directory tree:

.
|-- .python-version
|-- public
|   |-- .htaccess
|   |-- favicon.gif
|   |-- favicon.ico
|   |-- passenger_wsgi.py
|   `-- quickstart.html
`-- tmp
    `-- restart.txt

And this is my .htaccess:

PassengerPython /home/dh_user/.pyenv/versions/3.5.2/envs/flask/bin/python

<VirtualHost *:80>
    # This Flask web app will use Python 3.0
    ServerName api.example.com
    DocumentRoot /home/dh_user/api.example.com/public
</VirtualHost>

I have used all the guides below for help and reference:

https://help.dreamhost.com/hc/en-us/articles/215769548-Passenger-and-Python-WSGI https://www.phusionpassenger.com/library/walkthroughs/start/python.html https://www.byteconsole.com/get-flask-up-and-running-on-a-dreamhost-server-with-passenger/

Edit: Dreamhost doesn't allow me to look at the Passenger logs on a shared host. The best I can give you is my error.log, which, on every request, gives me

[Wed Apr 26 13:52:51 2017] [error] [client xxx.xxx.xxx.xxx] Premature end of script headers: 
[Wed Apr 26 13:52:51 2017] [error] [client xxx.xxx.xxx.xxx] Premature end of script headers: internal_error.html

Edit 2: I'm using the Paste Python module to collect errors from Flask and it's giving me this:

File '/home/dh_user/.pyenv/versions/3.5.2/envs/flask/lib/python3.5/site-packages/paste/exceptions/errormiddleware.py', line 224 in next
  return self.app_iterator.next()
AttributeError: 'ClosingIterator' object has no attribute 'next'

Please send the traceback. – stamaimer Apr 26 '17 at 04:13 — stamaimer, Apr 26 '17 at 04:13

score 0 · Answer 1 · answered Jan 17 '22 at 01:39

I added this to the top of my passenger_wsgi.py file and now the python errors go to my home directory:

import os,sys,os.path

errfile = open( '/home/user/error.log','a')
os.close(sys.stderr.fileno())
os.dup2(errfile.fileno(), sys.stderr.fileno())

Change /home/user/ to your dreamhost home directory, of course.

score -4 · Answer 2 · answered Apr 27 '17 at 02:13

-4

Well, I seem to have fixed it. What I can recall doing is removing Paste and the doing a few things after that.

answered Apr 27 '17 at 02:13

insertplus

33
8

What do you mean by saying " I can recall doing is removing Paste" and what are the "few things" you did after that? I don't think it's a helpful answer at all. – skepticNeophyte Oct 08 '22 at 08:33

Passenger running Flask site returning 500 error on Dreamhost

2 Answers2