chore(docker): update nltk data download process to include unstructured download_nltk_packages

[lework]

add unstructured download_nltk_packages， Fix the issue https://github.com/langgenius/dify/issues/28902.

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Summary

When using the document extractor, unstructured nltk files are automatically downloaded to the /home/dify/nltk_data/ directory.

dify@dify-api-7b8d54658f-cxnfr:/app/api$ ls -al /home/dify/nltk_data/tokenizers/
total 4236
drwxr-xr-x  3 dify dify    4096 Nov 28 02:39 .
drwxr-xr-x  4 dify dify    4096 Nov 28 02:38 ..
drwxr-xr-x 21 dify dify    4096 Nov 28 02:39 punkt_tab
-rw-r--r--  1 dify dify 4319076 Nov 28 02:39 punkt_tab.zip
dify@dify-api-7b8d54658f-cxnfr:/app/api$ ls -al /home/dify/nltk_data/t
taggers/    tokenizers/
dify@dify-api-7b8d54658f-cxnfr:/app/api$ ls -al /home/dify/nltk_data/taggers/
total 1516
drwxr-xr-x 3 dify dify    4096 Nov 28 02:38 .
drwxr-xr-x 4 dify dify    4096 Nov 28 02:38 ..
drwxr-xr-x 2 dify dify    4096 Nov 28 02:38 averaged_perceptron_tagger_eng
-rw-r--r-- 1 dify dify 1539115 Nov 28 02:38 averaged_perceptron_tagger_eng.zip

https://github.com/Unstructured-IO/unstructured/blob/91a9888d35b645988529e99b539eee9b7ffd30e3/unstructured/nlp/tokenize.py#L29

download_nltk_packages The downloaded packages do not match those specified in the Dockerfile, causing documents to be downloaded again during extraction. Use the download_nltk_packages method to download directly.

After modifying the Dockerfile to download in advance, unstructured will not download again.

dify@dify-api-6df5fdfb57-btp9k:/app/api$ ls -al /usr/local/share/nltk_data/taggers/
total 3988
drwxr-xr-x 4 root root    4096 Nov 28 06:26 .
drwxr-xr-x 5 root root    4096 Nov 28 06:26 ..
drwxr-xr-x 2 root root    4096 Nov 28 06:26 averaged_perceptron_tagger
-rwxr-xr-x 1 root root 2526731 Nov 28 06:26 averaged_perceptron_tagger.zip
drwxr-xr-x 2 root root    4096 Nov 28 06:26 averaged_perceptron_tagger_eng
-rwxr-xr-x 1 root root 1539115 Nov 28 06:26 averaged_perceptron_tagger_eng.zip
dify@dify-api-6df5fdfb57-btp9k:/app/api$ ls -al /usr/local/share/nltk_data/tokenizers/
total 17816
drwxr-xr-x  4 root root     4096 Nov 28 06:26 .
drwxr-xr-x  5 root root     4096 Nov 28 06:26 ..
drwxr-xr-x  3 root root     4096 Nov 28 06:26 punkt
-rwxr-xr-x  1 root root 13905355 Nov 28 06:26 punkt.zip
drwxr-xr-x 21 root root     4096 Nov 28 06:26 punkt_tab
-rwxr-xr-x  1 root root  4319076 Nov 28 06:26 punkt_tab.zip

Screenshots

Before	After
NLTK_DATA=/usr/local/share/nltk_data python -c "import nltk; nltk.download('punkt'); nltk.download('averaged_perceptron_tagger'); nltk.download('stopwords')"	&& NLTK_DATA=/usr/local/share/nltk_data python -c "import nltk; from unstructured.nlp.tokenize import download_nltk_packages; nltk.download('punkt'); nltk.download('averaged_perceptron_tagger'); nltk.download('stopwords'); download_nltk_packages()"

Checklist

• [ ] This change requires a documentation update, included: Dify Document
• [x] I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• [x] I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• [x] I've updated the documentation accordingly.
• [x] I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[gemini-code-assist[bot]]

Summary of Changes

Hello @lework, I'm Gemini Code Assist[^1]! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request optimizes the NLTK data download process within the Docker build for the API service. Previously, the unstructured library would trigger additional NLTK data downloads at runtime during document extraction, causing inefficiencies. By incorporating the download_nltk_packages function from unstructured.nlp.tokenize directly into the Dockerfile, all required NLTK data is now pre-downloaded during image creation, preventing redundant downloads and streamlining the document extraction workflow.

Highlights

• NLTK Data Download Optimization: Integrated the unstructured.nlp.tokenize.download_nltk_packages function directly into the Dockerfile build process to ensure all necessary NLTK data is pre-downloaded.
• Runtime Efficiency Improvement: Eliminated redundant NLTK data downloads that previously occurred during document extraction when using the unstructured library, leading to more efficient operations.

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[crazywoola]

Please create an issue and link it in the description.

[lework]

Please create an issue and link it in the description.

Added.

[lework]

@laipz8200 @QuantumGhost Please review.