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A check cell's declared memory is never silently clamped: forge.json says 8192, the cell enforced 4096 #3133

Merged scoutcrew opened this 24d agoin answer to trevatoowner

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A check cell's memory ceiling now defaults to 75% of the pod's `memory.max`. A `forge.json` memory limit above the ceiling puts a warning line in the check log, and a check stopped on memory says where its limit came from. The settings page isn't done. I could not run the full type check or suite here. `bun install` failed in this sandbox (read-only tempdir), so `tsc --noEmit` didn't run. The only…

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scoutcrew opened this 24d ago

A check cell's memory ceiling now defaults to 75% of the pod's memory.max. A forge.json memory limit above the ceiling puts a warning line in the check log, and a check stopped on memory says where its limit came from. The settings page isn't done. I could not run the full type check or suite here. bun install failed in this sandbox (read-only tempdir), so tsc --noEmit didn't run. The only test failure in my run was an existing shards test that can't find typescript/package.json for that reason.

What changed

Ceiling: memoryCeiling() in src/apps/contain.ts returns FORGE_CELL_MEMORY_MAX_MIB when set. Otherwise it returns 75% of the pod's /sys/fs/cgroup/memory.max, and 4096 when the host states no limit (no cgroup v2, or max). maxLimits() uses it.
Warning: limitWarnings() returns a line for each declared memory, cpu or disk limit the machine will cut. A line looks like warning: forge.json declares memory 8192 MiB; this machine grants at most 4096 (FORGE_CELL_MEMORY_MAX_MIB, else a share of the pod's memory). src/checks/service.ts writes these lines to the check log before the cell starts.
Kill message: a check stopped on memory now ends …over its 4096 MiB limit (the machine's ceiling, FORGE_CELL_MEMORY_MAX_MIB; a higher forge.json limit is held to it). When the limit came from forge.json or the default, it says that instead.
Tests: the new test/memory-ceiling.test.ts covers the ceiling (env, then pod, then 4096) and the warning (8192 declared against a 4096 ceiling warns; 2048 doesn't).
Changed existing test: the #3105 test in test/shards.test.ts expected 8192 to become 4096 with no env set. That contradicts a ceiling that follows the pod, so it now sets FORGE_CELL_MEMORY_MAX_MIB=4096 first. The test was wrong, not the code.

Left out

The settings page doesn't show the warning yet. The warning is in the check log only, so that should be a follow-up issue.
The README isn't updated.
The 75% share is my choice, not the issue's.

To try it: bun test test/memory-ceiling.test.ts test/shards.test.ts.

Closes #3128

scoutcrew commented 24d ago

What changed

Ceiling: memoryCeiling() in src/apps/contain.ts returns FORGE_CELL_MEMORY_MAX_MIB when set. Otherwise it returns 75% of the pod's /sys/fs/cgroup/memory.max, and 4096 when the host states no limit (no cgroup v2, or max). maxLimits() uses it.
Warning: limitWarnings() returns a line for each declared memory, cpu or disk limit the machine will cut. A line looks like warning: forge.json declares memory 8192 MiB; this machine grants at most 4096 (FORGE_CELL_MEMORY_MAX_MIB, else a share of the pod's memory). src/checks/service.ts writes these lines to the check log before the cell starts.
Kill message: a check stopped on memory now ends …over its 4096 MiB limit (the machine's ceiling, FORGE_CELL_MEMORY_MAX_MIB; a higher forge.json limit is held to it). When the limit came from forge.json or the default, it says that instead.
Tests: the new test/memory-ceiling.test.ts covers the ceiling (env, then pod, then 4096) and the warning (8192 declared against a 4096 ceiling warns; 2048 doesn't).
Changed existing test: the #3105 test in test/shards.test.ts expected 8192 to become 4096 with no env set. That contradicts a ceiling that follows the pod, so it now sets FORGE_CELL_MEMORY_MAX_MIB=4096 first. The test was wrong, not the code.

Left out

The settings page doesn't show the warning yet. The warning is in the check log only, so that should be a follow-up issue.
The README isn't updated.
The 75% share is my choice, not the issue's.

To try it: bun test test/memory-ceiling.test.ts test/shards.test.ts.

junipercrew Changes requested 24d ago— before the latest push

The ceiling now follows the pod, and the check log says when a declared limit is cut. Two things are missing against the list. I read the diff only and did not open the preview.

Fix first: the README does not say how to use any of this. Add FORGE_CELL_MEMORY_MAX_MIB, the 75% share of the pod memory.max, and the warning line in the check log. The list requires it.

Also:

memorySource has no test, so the new kill-message wording could break unnoticed. Add one covering the ceiling case and the forge.json case.
memorySource guesses where the limit came from by comparing it to the ceiling. A forge.json that declares exactly the ceiling gets told it was clamped when it was not. Carry the source with the resolved limit instead.
The cpus and disk warnings are beyond the issue, which is about memory. Either drop them or say why in the pull.
Warning only in the check log is not what the issue title asks for: it says the limit is never silently clamped, and the settings page still shows 8192. Open the follow-up issue the pull mentions, so the gap is tracked.

The shards test change is justified: that test assumed a fixed 4096 ceiling, and the ceiling now follows the pod.

scoutcrew commented 24d ago

I've addressed all five review points and pushed. I ran test/memory-ceiling.test.ts, which passes. test/shards.test.ts and test/cgroup.test.ts have one failure, an existing shards test that can't find typescript/package.json because bun install is blocked in this sandbox. I couldn't run tsc --noEmit for the same reason.

README: a new "A cell's memory ceiling" section under Limits covers FORGE_CELL_MEMORY_MAX_MIB, the 75% share of the pod's memory.max, the 4096 fallback, and the warning line in the check log.
Source carried with the limit: resolveLimits now sets memorySource to ceiling, declared or default, and the kill message reads that instead of comparing to the ceiling. A forge.json that declares exactly the ceiling is now reported as forge.json limits.memory, not as clamped.
Test: test/memory-ceiling.test.ts has a new case for memorySource covering the ceiling, forge.json (including exactly the ceiling), and default wording.
CPU and disk warnings: dropped. limitWarnings is memory only.
Settings page: opened #3134 for showing the effective limit there. Until it's done, the settings page still shows 8192, and the README says so.

junipercrew Changes requested 24d ago— before the latest push

The ceiling, the warning and the kill-message source are sound, and the shards test edit is justified. Two things still fail the bar. First: two behaviours added have no test that would fail without them. (1) The check log line: limitWarnings is unit-tested, but nothing proves startChecks writes it. Delete the loop in src/checks/service.ts and every test stays green. (2) The kill message in tick() (memorySource suffix) is only tested via memorySource(), not the breach text. Fix first: add a test that runs a check with forge.json memory above FORGE_CELL_MEMORY_MAX_MIB and asserts the log starts with the warning line. Second: the README says the ceiling applies to app cells too, but only check logs get the warning; an app declaring app.limits.memory above the ceiling is still clamped silently. Either warn at app start too, or word the README so it says the warning is check-only. The settings page still showing 8192 is tracked in #3134 and is fine to defer.

scoutcrew commented 24d ago

Both gaps are closed and pushed. I chose to word the README as check-only rather than add an app-start warning.

Check log wiring: test/check-memory-warning.test.ts runs a real check whose forge.json declares memory 8192 with the ceiling at 4096. It asserts the warning: forge.json declares memory 8192 MiB … grants at most 4096 line is in the log and comes before the command's $ line. I commented out the loop in src/checks/service.ts and this test failed, then restored the loop.
Kill message: watchTree is now exported. The same file's second test runs a process that holds about 200 MiB under a 64 MiB limit with source ceiling. It asserts the breach text is used N MiB of memory, over its 64 MiB limit (the machine's ceiling, FORGE_CELL_MEMORY_MAX_MIB; …. I also updated the regex in the cell memory test in test/contain.test.ts to expect the (the default) suffix. That test is skipped in this sandbox, so only the forge's check will run it.
README: it now says the warning is for checks only. An app declaring app.limits.memory above the ceiling is held to it without a line saying so, and the settings page doesn't show the cut either (#3134).

I ran test/check-memory-warning.test.ts and test/memory-ceiling.test.ts, which pass. I did not run tsc --noEmit, because bun install is blocked in this sandbox.

junipercrew Approved 24d ago

Approved. The change has no UI surface, so there is nothing to see in the preview. I read it from the diff and did not run the preview or open the screenshots. The ceiling follows the pod (env, then 75% of memory.max, then 4096). A declaration above it now puts a plain line in the check log before the command runs. A memory kill names the source of its limit, and a forge.json that declares exactly the ceiling is not called clamped. Each behaviour has a test. One test runs a real check and asserts the warning comes before the $ line, and the shards test change is justified. No new dependency and no security surface touched.

Two things I would do next:

Show the effective limit on the settings page and warn on app start (#3134). Until then an app cut to the ceiling is silent, which the README states honestly.
Wrap the long template-string line in limitWarnings in src/apps/contain.ts to match the file formatting. Also restore FORGE_CELLS in test/check-memory-warning.test.ts, as that file does for the ceiling variable.