Add dependency on native Tesseract OCR executable for pytesseract #1348
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The pytesseract package needs to have the `tesseract` executable available at runtime to work. By default, the Python package looks for the `tesseract` executable in the PATH. This doesn't work here, so we need to override the `tesseract_cmd` with the path to the `tesseract` executable we pulled in from Nix. I did this with a patch [based on how pytesseract is set up in Nixpkgs][1]. The patching code feels a bit fiddly. I don't know the idiomatic way to do this sort of thing. I included a test that will fail if pytesseract cannot find the `tesseract` executable. The test passed for me with both `preferWheels = true` and `preferWheels = false`, but I only included one in the test suite here, not sure if it makes sense to have both—the actual patching code had to be a bit different depending on whether the source was a wheel or not. [1]: https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/python-modules/pytesseract/tesseract-binary.patch
l0b0
reviewed
Oct 17, 2023
| ''; | ||
| in | ||
| super.pytesseract.overridePythonAttrs (old: { | ||
| buildInputs = (old.buildInputs or [ ]) ++ [ pkgs.tesseract4 ]; |
There was a problem hiding this comment.
Does this not need to be a propagatedBuildInput, to be available at runtime? In that case you might not need the patch.
There was a problem hiding this comment.
Good question, let me try it. I saw that the pytesseract default.nix in Nixpkgs used buildInputs, but I don't know if that's the best way to do it.
For reproducibility it seems better to have an explicit path to the executable rather than relying on the PATH variable where the script runs, so maybe that's the consideration.
There was a problem hiding this comment.
Okay, I tried changing it to propagatedBuildInputs and removing the patch, and the test case I wrote failed:
pytesseract.pytesseract.TesseractNotFoundError: tesseract is not installed or it's not in your PATH. See README file for more information.
cpcloud
approved these changes
Oct 21, 2023
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The pytesseract package needs to have the
tesseractexecutable available at runtime to work.By default, the Python package looks for the
tesseractexecutable in the PATH. This doesn't work here, so we need to override thetesseract_cmdwith the path to thetesseractexecutable we pulled in from Nix. I did this with a patch based on how pytesseract is set up in Nixpkgs.The patching code feels a bit fiddly. I don't know the idiomatic way to do this sort of thing.
I included a test that will fail if pytesseract cannot find the
tesseractexecutable. The test passed for me with bothpreferWheels = trueandpreferWheels = false, but I only included one in the test suite here, not sure if it makes sense to have both—the actual patching code had to be a bit different depending on whether the source was a wheel or not.