Add env support for the training script argument about elastic HOT 4 CLOSED

thanks for the feedback, should be simple enough to add. If we follow a convention of making the env var setting as TORCHELASTIC_{argument} (e.g. TORCHELASTIC_NNODES, TORCHELASTIC_NPROC_PER_NODE, TORCHELASTIC_RDZV_ID, etc) would this work?

from elastic.

LGTM, thanks for the support.

from elastic.

I had to use PET_{argument} (e.g. PET_NNODES, PET_NPROC_PER_NODE) - PET stands for Pytorch Elastic Trainer (our codename) - because TORCHELASTIC_ prefix is used internally by the torchelastic agent for certain things. The behavior is that the command-line argument wins over env vars and finally defaults to the default set in the program. For instance:

PET_NNODES=2 python -m torchelastic.distributed.launch --nnodes 3 script.py
# runs with 3 nodes not 2

positionals (script and script args) cannot be set via env vars. so you can't do something like this:

PET_TRAINING_SCRIPT="script.py" python -m torchelastic.distributed.launch --nnodes 3

Also flags can be set via env vars:

PET_STANDALONE=1 python -m torchelastic.distributed.launch --nnodes 3 script.py
#equivalent to
python -m torchelastic.distributed.launch --nnodes 3 --standalone script.py

PET_STANDALONE=0 python -m torchelastic.distributed.launch --nnodes 3 script.py
#equivalent to
python -m torchelastic.distributed.launch --nnodes 3 script.py

from elastic.

PR merged and released as part of torchelastic.0.2.1

from elastic.