docker
cli/compose: memswap_limit -> memory_swap, mem_swappiness -> memory_swappiness
- follow-up to https://github.com/docker/cli/pull/6619
Align the names in the compose / stack schema with the command-line flags, instead of aligning with the existing options in the compose-schema (which I think originated from v1); https://github.com/compose-spec/compose-spec/blob/a08f8d51631b7127ddac3d2c65537db429d0f1d0/spec.md?plain=1#L1440-L1461
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@ndeloof I'm guessing the naming originated from what was already in the compose-spec at a different place; https://github.com/compose-spec/compose-spec/blob/a08f8d51631b7127ddac3d2c65537db429d0f1d0/spec.md?plain=1#L1440-L1461
Would there be a motivation to align with those, or just go with this one?
## mem_swappiness
`mem_swappiness` defines as a percentage, a value between 0 and 100, for the host kernel to swap out
anonymous memory pages used by a container.
- `0`: Turns off anonymous page swapping.
- `100`: Sets all anonymous pages as swappable.
The default value is platform specific.
## memswap_limit
`memswap_limit` defines the amount of memory the container is allowed to swap to disk. This is a modifier
attribute that only has meaning if [`memory`](deploy.md#memory) is also set. Using swap lets the container write excess
memory requirements to disk when the container has exhausted all the memory that is available to it.
There is a performance penalty for applications that swap memory to disk often.
- If `memswap_limit` is set to a positive integer, then both `memory` and `memswap_limit` must be set. `memswap_limit` represents the total amount of memory and swap that can be used, and `memory` controls the amount used by non-swap memory. So if `memory`="300m" and `memswap_limit`="1g", the container can use 300m of memory and 700m (1g - 300m) swap.
- If `memswap_limit` is set to 0, the setting is ignored, and the value is treated as unset.
- If `memswap_limit` is set to the same value as `memory`, and `memory` is set to a positive integer, the container does not have access to swap.
- If `memswap_limit` is unset, and `memory` is set, the container can use as much swap as the `memory` setting, if the host container has swap memory configured. For instance, if `memory`="300m" and `memswap_limit` is not set, the container can use 600m in total of memory and swap.
- If `memswap_limit` is explicitly set to -1, the container is allowed to use unlimited swap, up to the amount available on the host system.
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The flags align with the ones on docker run, docker create
-m, --memory bytes Memory limit
--memory-reservation bytes Memory soft limit
--memory-swap bytes Swap limit equal to memory plus swap: '-1' to enable
unlimited swap
--memory-swappiness int Tune container memory swappiness (0 to 100) (default -1)
And docker update;
-m, --memory bytes Memory limit
--memory-reservation bytes Memory soft limit
--memory-swap bytes Swap limit equal to memory plus swap: -1 to enable unlimited swap
The new ones are on docker service create / docker service update;
--memory-swap bytes Swap Bytes (-1 for unlimited)
--memory-swappiness int Tune memory swappiness (0-100), -1 to reset to default
(default -1)
oh indeed, I guess it's to late to complain on https://github.com/docker/compose/issues/2383 that the compose attribute should align with CLI flags 🥲
Pending the discussion; we may need to go ahead with https://github.com/docker/cli/pull/6642 first, then move from there; would that be OK for you, @dperny ?