Add test for memory oversubscription.

Co-authored-by: Mahmood Ali <mahmood@hashicorp.com>

example/agent.hcl

@@ -8,6 +8,19 @@ plugin "containerd-driver" {
   }
 }
 
+server {
+  default_scheduler_config {
+    scheduler_algorithm = "spread"
+    memory_oversubscription_enabled = true
+
+    preemption_config {
+      batch_scheduler_enabled   = true
+      system_scheduler_enabled  = true
+      service_scheduler_enabled = true
+    }
+  }
+}
+
 client {
   host_volume "s1" {
     path = "/tmp/host_volume/s1"

example/redis.nomad

@@ -13,8 +13,9 @@ job "redis" {
       }
 
       resources {
-        cpu    = 500
-        memory = 256
+        cpu        = 500
+        memory     = 256
+        memory_max = 512
       }
     }
   }

tests/001-test-redis.sh

@@ -49,6 +49,19 @@ test_redis_nomad_job() {
        exit 1
     fi
 
+    echo "INFO: Check if memory and memory_max are set correctly in the cgroup filesystem."
+    task_name=$(sudo CONTAINERD_NAMESPACE=nomad ctr containers ls|awk 'NR!=1'|cut -d' ' -f1)
+    memory_soft_limit=$(sudo cat /sys/fs/cgroup/memory/nomad/$task_name/memory.soft_limit_in_bytes)
+    if [ $memory_soft_limit != "$(( 256 * 1024 * 1024 ))" ]; then
+       echo "ERROR: memory should be 256 MB. Found ${memory_soft_limit}."
+       exit 1
+    fi
+    memory_hard_limit=$(sudo cat /sys/fs/cgroup/memory/nomad/$task_name/memory.limit_in_bytes)
+    if [ $memory_hard_limit != "$(( 512 * 1024 * 1024 ))" ]; then
+       echo "ERROR: memory_max should be 512 MB. Found ${memory_hard_limit}."
+       exit 1
+    fi
+
     echo "INFO: Stopping nomad redis job."
     nomad job stop redis
     redis_status=$(nomad job status -short redis|grep Status|awk '{split($0,a,"="); print a[2]}'|tr -d ' ')