How to use poppler buildpack on Heroku

Question

I want to use pdf2image that is python package on Heroku, and it needs poppler so I have to add poppler buildpack.

I added https://github.com/survantjames/heroku-buildpack-poppler.git with referance to Install poppler onto Heroku Server django but my app showed error and crashed.

So I checked with bash on Heroku, path of poppler's bin direcroty is added enviroment variable but poppler utils fail and don't work.

The error message of pdfinfo (one of poppler utils) is:

pdfinfo: error while loading shared libraries: libpng12.so.0: cannot open shared object file: No such file or directory

In response to this, I added libpng12 buildpack from https://elements.heroku.com/buildpacks/freddix/libpng12 but it didn't improve. How do I use poppler buildpack on Heroku?

buildpacks:

1. https://github.com/survantjames/heroku-buildpack-poppler.git
2. heroku/python

app's code(python3):

from flask import Flask, Response
import pdf2image
import io

app = Flask(__name__)


@app.route('/')
def index():
    return 'Hello, World!'

@app.route('/img/')
def img():
    img = pdf2image.convert_from_path(f'{app.root_path}/static/pdf/miku.pdf')[0]
    buffer = io.BytesIO()
    img.save(buffer, 'PNG')
    return Response(buffer.getvalue(), mimetype='image/png')


if __name__ == '__main__':
    app.run()

Answer 1

The solution worked for me with some edits(Python 3):

1. Add the buildpack to Heroku:

   heroku buildpacks:set heroku/python

   heroku buildpacks:add --index 1 heroku-community/apt

2. Make a file named Aptfile in your project folder and write build-essential libpoppler-cpp-dev pkg-config python3-dev inside.