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F1 (rework): source guest RAM cap from docker info; deploy guard uses committed memory

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The cgroup-only approach was a no-op on the demo: the controller container's OWN
cgroup is unlimited (the 2GB cap is on the LXC ancestor, hidden), and /proc has no
lxcfs, so it kept reporting the host's 16GB. The Docker daemon runs IN the LXC, so
'docker info' MemTotal reports the guest's real cap (2048MB) — now the authoritative
source (cgroup limit preferred when present, e.g. non-nested). The deploy memory
guard now uses the controller's committed-app memory (sum of running mem requests)
for 'used' — accurate and cheap — instead of host /proc RSS (unobservable per guest;
would make the guard never/always fire). /api/system/info reports the guest cap as
total and committed memory as used. Tests: cgroup-limit path, docker-info fallback
(nested case), GuestMemTotalMB fallback (dockerMemTotalFn stub).
This commit is contained in:
authentik Default Admin
2026-06-14 10:18:22 +02:00
parent d6c428b5dd
commit 4989513a96
5 changed files with 142 additions and 23 deletions
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controller/internal/stacks/deploy.go
+14 -2
View File
@@ -160,16 +160,28 @@ func (m *Manager) DeployStack(req DeployRequest) (string, error) {
var deployWarning string
reservedMB := m.cfg.System.ReservedMemoryMB
totalMB, usedMB, memErr := system.GetMemoryMB()
// F1: the controller container cannot read the guest's RAM cap from /proc (no lxcfs) or its own
// cgroup (the cap is on the LXC ancestor). Prefer the guest cap from the Docker daemon (runs in the
// LXC). And use the controller's OWN committed-memory accounting for "used" — accurate and cheap —
// rather than host /proc RSS, which is unobservable-per-guest and would otherwise make this guard
// either never fire (host total) or always fire (host used > guest cap).
if gt, ok := system.GuestMemTotalMB(); ok && gt > 0 {
totalMB = gt
memErr = nil
}
if committedReqMB, _ := m.CommittedMemory(); committedReqMB > 0 || memErr == nil {
usedMB = committedReqMB
}
if memErr != nil {
m.logger.Printf("[WARN] [stacks] Cannot read system memory: %v — skipping memory check", memErr)
} else {
usableMB := totalMB - reservedMB
newReqMB := ParseMemoryMB(meta.Resources.MemRequest)
m.logger.Printf("[INFO] [stacks] Memory check: total=%dMB, reserved=%dMB, usable=%dMB, real_used=%dMB, new_req=%dMB, remaining=%dMB",
m.logger.Printf("[INFO] [stacks] Memory check: total=%dMB, reserved=%dMB, usable=%dMB, committed_used=%dMB, new_req=%dMB, remaining=%dMB",
totalMB, reservedMB, usableMB, usedMB, newReqMB, usableMB-usedMB-newReqMB)
// Hard block: real used + new request exceeds usable memory
// Hard block: committed + new request exceeds usable memory
if newReqMB > 0 && usedMB+newReqMB > usableMB {
clearDeploying()
return "", fmt.Errorf(