Flask application built using pyinstaller not rendering index.html

Question

I have written a flask application and it works perfectly fine. I wanted to distribute it as an executable. Tried doing it using pyinstaller flaskScript.py dist folder got

Answer 1

This question is a bit old now, but I was having the same problem (Python 3.4.3, Flask 0.10.1 and PyInstaller 3.1.1) when packaging it to a single file.

I've managed to solve it by adding the following to the initialization script (app\__init__.py):

import sys
import os
from flask import Flask
# Other imports

if getattr(sys, 'frozen', False):
    template_folder = os.path.join(sys._MEIPASS, 'templates')
    app = Flask(__name__, template_folder=template_folder)
else:
    app = Flask(__name__)

# etc

The problem is that when the site is running in packaged form, the templates are inside a directory called _MEIxxxxxx under the temp directory (see this in the PyInstaller Manual) so we have to tell that to Flask.

That is done with the template_folder argument (which I found out about in this answer here and later in the API docs).

Finally, the if is there to ensure that we can still use it unpackaged while developing it. If it is frozen, then the script is packaged and we have to tell Flask where to find the templates; otherwise we're running it in a Python environment (taken from here) and the defaults will work (assuming you're using the standard templates directory of course).

Answer 2

I've just wrote a blog post about this problem and others similar, Create one executable file for a Flask app with PyInstaller

Basically an elegant solution is to execute the following:

Windows

pyinstaller -w -F --add-data "templates;templates" --add-data "static;static" app.py

Linux (NOT TESTED)

pyinstaller -w -F --add-data "templates:templates" --add-data "static:static" app.py

Answer 3

If you are trying to create a --onefile executable you will also need to add the directories in the spec file.

1. In the Python code, find where the application is running and store the path in base_dir:

   import os, sys
   base_dir = '.'
   if hasattr(sys, '_MEIPASS'):
       base_dir = os.path.join(sys._MEIPASS)
   

2. Pass the proper paths to the Flask app using the `static_folder and template_folder parameters:

   app = Flask(__name__,
           static_folder=os.path.join(base_dir, 'static'),
           template_folder=os.path.join(base_dir, 'templates'))
   

3. In the spec file, we do need to tell pyinstaller to include the templates and static folder including the corresponding folders in the Analysis section of the pyinstaller:

   a = Analysis(
        ...
        datas=[
          ('PATH_TO_THE_APP\\static\\', 'static'),
          ('PATH_TO_THE_APP\\templates\\', 'templates'),
        ],
        ...
   

---

A bit of explanation:

The general problem with not finding files after packaging with pyinstaller is that the files will change its path. With the --onefile option your files will be compressed inside the exe. When you execute the exe, they are uncompressed and put in a temporal folder somewhere.

Tha somewhere changes everytime you execute the file, but the running application (not the spec file, but your main python file, say main.py) can be found here:

import os
os.path.join(sys._MEIPASS)

So, the templates files won't be in ./templates, but in os.path.join(os.path.join(sys._MEIPASS), templates). The problem now is that your code won't run unless it is packaged. Therefore, python main.py won't run.

Therefore a condition is required to find the files in the right place:

import os, sys
base_dir = '.'
if hasattr(sys, '_MEIPASS'): # or, untested: if getattr(sys, 'frozen', False):
    base_dir = os.path.join(sys._MEIPASS)

Here is more regarding runtime information in pyinstaller

Answer 4

if getattr(sys, 'frozen', False):                                                                                                                                     
      template_folder = os.path.join(sys.executable, '..','templates')                                                                                                  
      static_folder = os.path.join(sys.executable, '..','static')                                                                                                       
      app = Flask(__name__, template_folder = template_folder,\                                                                                                         
                              static_folder = static_folder)

copy this code and paste in your file. now pyinstaller looks for static and template folder in your dist directory. Now copy and paste static and template folder in your dist folder. it will works

Answer 5

if you're building from a .spec file this can easily be accomplished without altering

__int__.py

1) add your templates and static folder to datas in .spec

2) make sure to add jinja2 to hiddenimports

block_cipher = None

# add templates and static folders to a list
added_files =[
    ('templates/*.html', 'templates'),
    ('static/*.css', 'static'),
    ]

a = Analysis(['run.py'],
             pathex=['/your/app/location'],
             binaries=[],
             datas = added_files, # set datas = added_files list
             hiddenimports=['jinja2.ext'], # be sure to add jinja2 
             hookspath=[],
             runtime_hooks=[],
             excludes=[],
             win_no_prefer_redirects=False,
             win_private_assemblies=False,
             cipher=block_cipher,
             noarchive=False)
             ...

this method is directly from the pyinstaller docs here