snapshot of https://github.com/mattermost/mattermost.git (master, 2026-09-16; blobs > 131072B omitted)

server/channels/app/platform/container_limits_linux.go

@@ -0,0 +1,89 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+//go:build linux
+
+package platform
+
+import (
+	"errors"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// cgroupPaths holds the file paths used to read cgroup v2 resource limits.
+// These are package-level variables so they can be overridden in tests.
+var cgroupPaths = struct {
+	v2MemoryMax string
+	v2CPUMax    string
+}{
+	v2MemoryMax: "/sys/fs/cgroup/memory.max",
+	v2CPUMax:    "/sys/fs/cgroup/cpu.max",
+}
+
+// ContainerLimits holds effective CPU and memory limits for the current container.
+// Zero values indicate no limit is set (fields will be omitted from YAML output).
+type ContainerLimits struct {
+	CPULimit      float64
+	MemoryLimitMB uint64
+}
+
+// getContainerLimits reads container resource limits from cgroups v2.
+// Returns zero values when no limits are detected (bare metal, unlimited, or non-v2 system).
+func getContainerLimits() (ContainerLimits, error) {
+	var limits ContainerLimits
+
+	// Memory limit: "max" means unlimited, otherwise bytes
+	memStr, err := readTrimmed(cgroupPaths.v2MemoryMax)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return limits, nil
+		}
+		return limits, err
+	}
+	if memStr != "max" {
+		var memBytes uint64
+		memBytes, err = strconv.ParseUint(memStr, 10, 64)
+		if err != nil {
+			return limits, err
+		}
+		limits.MemoryLimitMB = (memBytes + 1024*1024 - 1) / (1024 * 1024)
+	}
+
+	// CPU limit: format is "quota period"; quota is "max" when unlimited
+	cpuStr, err := readTrimmed(cgroupPaths.v2CPUMax)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return limits, nil
+		}
+		return limits, err
+	}
+	parts := strings.Fields(cpuStr)
+	if len(parts) != 2 {
+		return limits, errors.New("unexpected format in cpu.max")
+	}
+	if parts[0] != "max" {
+		quota, err := strconv.ParseFloat(parts[0], 64)
+		if err != nil {
+			return limits, err
+		}
+		period, err := strconv.ParseFloat(parts[1], 64)
+		if err != nil {
+			return limits, err
+		}
+		if period > 0 {
+			limits.CPULimit = quota / period
+		}
+	}
+
+	return limits, nil
+}
+
+func readTrimmed(path string) (string, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(data)), nil
+}