docker / docker/docker-py

cpu_limit unit discrepancy

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Description

I have a question + potential concern regarding the precision of cpu_limit within the Resources class (line 298 of docker/types/services.py).

According to both this file and the docker-py docs (https://docker-py.readthedocs.io/en/stable/api.html#docker.types.Resources), the cpu_limit of the resources class is in units of 10^9 CPU shares. However, in the code, we have the line:

limits['NanoCPUs'] = cpu_limit

Would it be safe to say, then, that this cpu_limit is actually in units of 10^-9 CPU shares (given the Nano prefix above)? Otherwise, the documentation leads me to think that setting cpu_limit=1 results in allocating 10^9 CPU shares.

Also, would allocating these shares be the same as just specifying the --cpu-shares option in docker?

Please let me know. Thank you.

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Research direction

Start at line 298 of docker/types/services.py and read the Resources class and its handling of cpu_limit. Compare the code with the linked docker-py API documentation and the Docker Engine meanings of NanoCPUs and --cpu-shares. Done means the units and relationship are resolved and the relevant documentation or code comments are made consistent.

Written by the indexing model from the issue text.

Assessment

Tech stack
docker, python
Domain
backend-api-design, documentation
Issue type
Documentation
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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