ruler os.environ fix

[f14-bertolotti]

Motivation

Running the ruler benchmark (pencompass/configs/datasets/ruler/ruler_16k_gen.py) raised a model engine error related to the usage of os.environ.get(...). The traceback is as follows:

Traceback (most recent call last):
  File "/leonardo_work/iGen_train/fbertolo/llm-research/eval/../third_party/opencompass/run.py", line 4, in <module>
    main()
  File "/leonardo_work/iGen_train/fbertolo/llm-research/third_party/opencompass/opencompass/cli/main.py", line 259, in main
    cfg = get_config_from_arg(args)
  File "/leonardo_work/iGen_train/fbertolo/llm-research/third_party/opencompass/opencompass/utils/run.py", line 97, in get_config_from_arg
    config = Config.fromfile(args.config, format_python_code=False)
  File "/leonardo_scratch/fast/iGen_train/fbertolo/eval/venv/lib/python3.10/site-packages/mmengine/config/config.py", line 494, in fromfile
    raise e
  File "/leonardo_scratch/fast/iGen_train/fbertolo/eval/venv/lib/python3.10/site-packages/mmengine/config/config.py", line 492, in fromfile
    cfg_dict, imported_names = Config._parse_lazy_import(filename)
  File "/leonardo_scratch/fast/iGen_train/fbertolo/eval/venv/lib/python3.10/site-packages/mmengine/config/config.py", line 1081, in _parse_lazy_import
    _base_cfg_dict, _base_imported_names = Config._parse_lazy_import(  # noqa: E501
  File "/leonardo_scratch/fast/iGen_train/fbertolo/eval/venv/lib/python3.10/site-packages/mmengine/config/config.py", line 1081, in _parse_lazy_import
    _base_cfg_dict, _base_imported_names = Config._parse_lazy_import(  # noqa: E501
  File "/leonardo_scratch/fast/iGen_train/fbertolo/eval/venv/lib/python3.10/site-packages/mmengine/config/config.py", line 1109, in _parse_lazy_import
    exec(
  File "/leonardo_work/iGen_train/fbertolo/llm-research/third_party/opencompass/opencompass/configs/datasets/ruler/ruler_16k_gen.py", line 17, in <module>
    tokenizer_model = os.environ.get('TOKENIZER_MODEL', 'gpt-4')
  File "/leonardo_scratch/fast/iGen_train/fbertolo/eval/venv/lib/python3.10/site-packages/mmengine/config/lazy.py", line 205, in __call__
    raise RuntimeError()
RuntimeError

This error affects all ruler_<number>k_gen.py.

Modification

To resolve this, I replaced os.environ.get(...) with os.environ.build().get(...), which I have used successfully in similar model engine contexts. An alternative is to use the {{$ENV_NAME:value}} syntax, but this tends to introduce additional complexity and potential errors.

Checklist

Before PR:

[] Pre-commit or other linting tools have been used to fix potential lint issues.
[] Bug fixes are covered by unit tests, including the case that causes the bug.
[] Modifications are covered by complete unit tests.
[] Documentation has been updated accordingly (e.g. docstrings, tutorials).

After PR:

[] If the modification potentially influences downstream or related projects, it has been tested with those projects.
[] CLA has been signed, and all committers have signed the CLA for this PR.

PS

sorry for previous PR (I forgot to change branch)