Changes:

• create single workflow for multiple containerized Linux builds using matrix build (branch, ubuntu version)
  • enable AVX2 for 24.04, enable plugins for 22.04, enable python limited API for 20.04
• simplify dnn models download (just run the script)
• extract separate actions for clone+merge, configure+build and test
  • use grouping to make collapsible blocks and error/notice formatting to show failures in subtests
  • combine build and build+contrib in single job
    • check for warnings using new modified script
  • add wrapper script for gtest runs (runner.py)
    • use json test plan file for list of modules, filters and other options
    • show only test failures and summary
    • save test output as artifacts
    • collect test status to markdown summary
  • do not save java test results as artifact
• simplify environment variables, move some variables to their specific actions, add some new variables controlling build/test behavior (e.g. CMAKE_BUILD_PARALLEL_LEVEL)
• The same workflow is also applicable to opencv_contrib repository

Things to be discussed:

• add CUDA and OpenVINO builds to the set - we can add them as a separate job, or as new configurations in the Ubuntu job
• test set for opencv_contrib repository - currently it runs all tests, we can limit it to the opencv_contrib only
• timeouts - currently we have 360 min for whole workflow (default), 60 min for dnn models download (explicit) and 10 min for each module test (runner script)
• thread count - currently it is set to 8 for build and test

Things which can be improved:

• check cmake warnings
• add more information to the summary (e.g. warnings, test statistics, timings, system information, build configuration, etc.)
• move dnn models update to separate action or to the checkout-and-merge action
• show beginning of test output in the log
• done implement better timeout handling in the runner script (e.g. using asyncio)
• sync home directory, user name and other common things in Ubuntu docker images
• warn or exit if default branch name has been used as a source in the PR (4.x, 5.x) to avoid merging unexpected changes from other repositories
• re-enable ASAN builds

Known issues:

• Sporadic connection problems when uploading artifacts: Failed to CreateArtifact: Unable to make request: ECONNRESET If you are using self-hosted runners, please make sure your runner has access to all GitHub endpoints: https://docs.github.com/en/actions/hosting-your-own-runners/managing-self-hosted-runners/about-self-hosted-runners#communication-between-self-hosted-runners-and-github