How to install NLTK modules in Heroku

Question

Hey i\'d like to install the NLTK pos_tag on my Heroku server. How can i do so. Please give me the steps as im new to the Heroku server system.

Answer 1

Update

As Kenneth Reitz pointed out, a much simpler solution has been added to the heroku-python-buildpack. Add a nltk.txt file to your root directory and list your corpora inside. See https://devcenter.heroku.com/articles/python-nltk for details.

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Original Answer

Here's a solution that allows you to install the NLTK data directly on Heroku without adding it to your git repo.

I used similar steps to install Textblob on Heroku, which uses NLTK as a dependency. I've made some minor adjustments to my original code in steps 3 and 4 that should work for an NLTK only installation.

The default heroku buildpack includes a post_compile step that runs after all of the default build steps have been completed:

# post_compile
#!/usr/bin/env bash

if [ -f bin/post_compile ]; then
    echo "-----> Running post-compile hook"
    chmod +x bin/post_compile
    sub-env bin/post_compile
fi

As you can see, it looks in your project directory for your own post_compile file in the bin directory, and it runs it if it exists. You can use this hook to install the nltk data.

1. Create the bin directory in the root of your local project.

2. Add your own post_compile file to the bin directory.

   # bin/post_compile
   #!/usr/bin/env bash
   
   if [ -f bin/install_nltk_data ]; then
       echo "-----> Running install_nltk_data"
       chmod +x bin/install_nltk_data
       bin/install_nltk_data
   fi
   
   echo "-----> Post-compile done"
   

3. Add your own install_nltk_data file to the bin directory.

   # bin/install_nltk_data
   #!/usr/bin/env bash
   
   source $BIN_DIR/utils
   
   echo "-----> Starting nltk data installation"
   
   # Assumes NLTK_DATA environment variable is already set
   # $ heroku config:set NLTK_DATA='/app/nltk_data'
   
   # Install the nltk data
   # NOTE: The following command installs the averaged_perceptron_tagger corpora, 
   # so you may want to change for your specific needs.  
   # See http://www.nltk.org/data.html
   python -m nltk.downloader averaged_perceptron_tagger
   
   # If using Textblob, use this instead:
   # python -m textblob.download_corpora lite
   
   # Open the NLTK_DATA directory
   cd ${NLTK_DATA}
   
   # Delete all of the zip files
   find . -name "*.zip" -type f -delete
   
   echo "-----> Finished nltk data installation"
   

4. Add nltk to your requirements.txt file (Or textblob if you are using Textblob).

5. Commit all of these changes to your repo.

6. Set the NLTK_DATA environment variable on your heroku app.

   $ heroku config:set NLTK_DATA='/app/nltk_data'
   

7. Deploy to Heroku. You will see the post_compile step trigger at the end of the deployment, followed by the nltk download.

I hope you found this helpful! Enjoy!