How to get WKHTMLTOPDF working on Heroku? - python-3.x

Question

I created a website which generates PDF using PDFKIT and I know how to install and setup environment variable path on Window. I managed to deploy my first website on Heroku but now I'm getting error "No wkhtmltopdf executable found: "b''" When trying to generate the PDF.
I have no idea, How to install and setup WKHTMLTOPDF on Heroku because this is first time I'm dealing with Linux.
I really tried everything before asking this but even following this not working for me.
Python 3 flask install wkhtmltopdf on heroku
If possible, please guide me with step by step on how to install and setup this.
I followed all the resource and everything but couldn't make it work. Every time I get the same error.
I'm using Django version 2. Python version 3.7.
This is what I get if I do heroku stack
Available Stacks
cedar-14
container
heroku-16
* heroku-18
Error, I'm getting when generating the PDF.
No wkhtmltopdf executable found: "b''"
If this file exists please check that this process can read it. Otherwise please install wkhtmltopdf - https://github.com/JazzCore/python-pdfkit/wiki/Installing-wkhtmltopdf
My website works very well on localhost without any problem and as far as I know, I'm sure that I have done something wrong in installing wkhtmltopdf.
Thank you

Answer 1

It's non-trivial. If you want to avoid all of the below's headache, you can just use my service, api2pdf: https://github.com/api2pdf/api2pdf.python. Otherwise, if you want to try and work through it, see below.
1) Add this to your requirements.txt to install a special wkhtmltopdf pack for heroku as well as pdfkit.
git+git://github.com/johnfraney/wkhtmltopdf-pack.git
pdfkit==0.6.1
2) I created a pdf_manager.py in my flask app. In pdf_manager.py I have a method:
def _get_pdfkit_config():
"""wkhtmltopdf lives and functions differently depending on Windows or Linux. We
need to support both since we develop on windows but deploy on Heroku.
Returns:
A pdfkit configuration
"""
if platform.system() == 'Windows':
return pdfkit.configuration(wkhtmltopdf=os.environ.get('WKHTMLTOPDF_BINARY', 'C:\\Program Files\\wkhtmltopdf\\bin\\wkhtmltopdf.exe'))
else:
WKHTMLTOPDF_CMD = subprocess.Popen(['which', os.environ.get('WKHTMLTOPDF_BINARY', 'wkhtmltopdf')], stdout=subprocess.PIPE).communicate()[0].strip()
return pdfkit.configuration(wkhtmltopdf=WKHTMLTOPDF_CMD)
The reason I have the platform statement in there is that I develop on a windows machine and I have the local wkhtmltopdf binary on my PC. But when I deploy to Heroku, it runs in their linux containers so I need to detect first which platform we're on before running the binary.
3) Then I created two more methods - one to convert a url to pdf and another to convert raw html to pdf.
def make_pdf_from_url(url, options=None):
"""Produces a pdf from a website's url.
Args:
url (str): A valid url
options (dict, optional): for specifying pdf parameters like landscape
mode and margins
Returns:
pdf of the website
"""
return pdfkit.from_url(url, False, configuration=_get_pdfkit_config(), options=options)
def make_pdf_from_raw_html(html, options=None):
"""Produces a pdf from raw html.
Args:
html (str): Valid html
options (dict, optional): for specifying pdf parameters like landscape
mode and margins
Returns:
pdf of the supplied html
"""
return pdfkit.from_string(html, False, configuration=_get_pdfkit_config(), options=options)
I use these methods to convert to PDF.

Answer 2

Just follow these steps to Deploy Django app(pdfkit) on Heroku:
Step 1:: Add following packages in requirements.txt file
wkhtmltopdf-pack==0.12.3.0
pdfkit==0.6.0
Step 2: Add below lines in the views.py to add path of binary file
import os, sys, subprocess, platform
if platform.system() == "Windows":
pdfkit_config = pdfkit.configuration(wkhtmltopdf=os.environ.get('WKHTMLTOPDF_BINARY', 'C:\\Program Files\\wkhtmltopdf\\bin\\wkhtmltopdf.exe'))
else:
os.environ['PATH'] += os.pathsep + os.path.dirname(sys.executable)
WKHTMLTOPDF_CMD = subprocess.Popen(['which', os.environ.get('WKHTMLTOPDF_BINARY', 'wkhtmltopdf')],
stdout=subprocess.PIPE).communicate()[0].strip()
pdfkit_config = pdfkit.configuration(wkhtmltopdf=WKHTMLTOPDF_CMD)
Step 3: And then pass pdfkit_config as argument as below
pdf = pdfkit.from_string(html,False,options, configuration=pdfkit_config)