Guidence on caching

[Oliver Rice]

The actions takes 35-40 mins to run

Is there any support for caching so it can be skipped so long as none of the settings have changed?

This project was a huge help getting our CI working, thanks for putting it together

[Fernando Bevilacqua]

I am really glad you like (and are using) it! I face the very same problems with my own CI tests, but I don't think you can persist data from one action run to another.

Consulting the Github Actions docs now, I've found this:

If you need to access artifacts from a previous workflow run, you'll need to store the artifacts somewhere. For example, you could run a script at the end of your workflow to store build artifacts on Amazon S3 or Artifactory, and then use the storage service's API to retrieve those artifacts in a future workflow.

Maybe the setup-opencv-action could have some sort of config params to upload the compiled files to a place, then download them in the future if all params are the same.

My fear is that it is too specific to be integrated into the action itself.

[Fernando Bevilacqua]

I've just got to know GitHub cache action: https://github.com/actions/cache

I think this is exactly what you are looking for!

[Oliver Rice]

thank you! i was able to get that working

[Fernando Bevilacqua]

Awesome! If you have a .yml snippet you would like to share, I can add it to the docs so other users can use this. Just a suggestion, please don't feel required to 😉

[Oliver Rice]

Ok, I fibbed a little

I was able to get the cache working via:

name: Tests

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    - name: Cache OpenCV
      id: cache-opencv
      uses: actions/cache@v2
      with:
          path: /usr/local
          key: fixed-opencv-cache
    
    - name: Install OpenCV
      if: steps.cache-opencv.output.cache-hit != 'true'
      uses: Dovyski/setup-opencv-action@v1
      with:
        opencv-version: '4.3.0'

Which admittedly caches far more than is actually necessary (note the 5GB size below) but I was just trying to get POC.

The issue crops up on subsequent runs when it tries to restore the cache it errors out because that's a protected part of the file system

 Cache OpenCV
3m 48s
/bin/tar: ../../../../../usr/local/src: Cannot utime: Operation not permitted
Run actions/cache@v2
Cache Size: ~5009 MB (5251874814 B)
/bin/tar --use-compress-program zstd -d -xf /home/runner/work/_temp/f844c62f-0070-413f-93e1-48b7bd195f64/cache.tzst -P -C /home/runner/work/ClosedCV/ClosedCV
/bin/tar: ../../../../../usr/local/man/man7/cmake-generator-expressions.7: Cannot open: File exists
/bin/tar: ../../../../../usr/local/man/man7/cmake-packages.7: Cannot open: File exists
/bin/tar: ../../../../../usr/local/man/man7/cmake-variables.7: Cannot open: File exists

I'm sure it would be possible to install in a different location and restore the cache but the project this was intended to support got dropped before I invested the time to solve that issue.

Maybe this will help as a starting point for others, but its not an out-of-the-box solution

[Fernando Bevilacqua]

Thank you very much for this starting point. I'll use it to iterate on for sure.

[Amit Moryossef]

If anybody has a better solution by now, I'd love to know!

[Tzuriel Lampner]

I stumbled upon porg package which can track installed files.
The list of installed files can be extracted and fed into actions/cache@v2