From 53ef6391a566720e93c3a8926bc5d21ec98acdb1 Mon Sep 17 00:00:00 2001
From: Piotr Kazmierczak <470696+pkazmierczak@users.noreply.github.com>
Date: Thu, 17 Aug 2023 14:45:31 +0200
Subject: [PATCH] drivers/docker: fix a hostConfigMemorySwappiness panic
 (#18238)

cgroupslib.MaybeDisableMemorySwappiness returned an incorrect type, and was
incorrectly typecast to int64 causing a panic on non-linux and non-windows hosts.
---
 client/lib/cgroupslib/default.go | 2 +-
 drivers/docker/driver.go         | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/client/lib/cgroupslib/default.go b/client/lib/cgroupslib/default.go
index 8c8d277e0..12376bc95 100644
--- a/client/lib/cgroupslib/default.go
+++ b/client/lib/cgroupslib/default.go
@@ -11,6 +11,6 @@ func LinuxResourcesPath(string, string) string {
 }
 
 // MaybeDisableMemorySwappiness does nothing on non-Linux systems
-func MaybeDisableMemorySwappiness() *int {
+func MaybeDisableMemorySwappiness() *uint64 {
 	return nil
 }
diff --git a/drivers/docker/driver.go b/drivers/docker/driver.go
index 13f873c74..cf4dfb190 100644
--- a/drivers/docker/driver.go
+++ b/drivers/docker/driver.go
@@ -33,6 +33,7 @@ import (
 	"github.com/hashicorp/nomad/drivers/shared/hostnames"
 	"github.com/hashicorp/nomad/drivers/shared/resolvconf"
 	"github.com/hashicorp/nomad/helper"
+	"github.com/hashicorp/nomad/helper/pointer"
 	nstructs "github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/nomad/plugins/base"
 	"github.com/hashicorp/nomad/plugins/drivers"
@@ -1035,8 +1036,11 @@ func (d *Driver) createContainerConfig(task *drivers.TaskConfig, driverConfig *T
 		hostConfig.MemorySwap = memory
 
 		// disable swap explicitly in non-Windows environments
-		swappiness := int64(*(cgroupslib.MaybeDisableMemorySwappiness()))
-		hostConfig.MemorySwappiness = &swappiness
+		if cgroupslib.MaybeDisableMemorySwappiness() != nil {
+			hostConfig.MemorySwappiness = pointer.Of(int64(*(cgroupslib.MaybeDisableMemorySwappiness())))
+		} else {
+			hostConfig.MemorySwappiness = nil
+		}
 	}
 
 	loggingDriver := driverConfig.Logging.Type