docker: oom_score_adj support (#23297)

.changelog/23297.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+docker: Added support for oom_score_adj
+```

drivers/docker/config.go

@@ -290,6 +290,13 @@ var (
 			hclspec.NewLiteral(`5`),
 		),
 
+		// oom_score_adj is the positive integer that can be used to mark the task as
+		// more likely to be OOM killed
+		"oom_score_adj": hclspec.NewDefault(
+			hclspec.NewAttr("oom_score_adj", "number", false),
+			hclspec.NewLiteral(`0`),
+		),
+
 		// the duration that the driver will wait for activity from the Docker engine during an image pull
 		// before canceling the request
 		"pull_activity_timeout": hclspec.NewDefault(
@@ -392,6 +399,7 @@ var (
 		"mounts":          hclspec.NewBlockList("mounts", mountBodySpec),
 		"network_aliases": hclspec.NewAttr("network_aliases", "list(string)", false),
 		"network_mode":    hclspec.NewAttr("network_mode", "string", false),
+		"oom_score_adj":   hclspec.NewAttr("oom_score_adj", "number", false),
 		"runtime":         hclspec.NewAttr("runtime", "string", false),
 		"pids_limit":      hclspec.NewAttr("pids_limit", "number", false),
 		"pid_mode":        hclspec.NewAttr("pid_mode", "string", false),
@@ -469,6 +477,7 @@ type TaskConfig struct {
 	Mounts                  []DockerMount      `codec:"mount"`
 	NetworkAliases          []string           `codec:"network_aliases"`
 	NetworkMode             string             `codec:"network_mode"`
+	OOMScoreAdj             int                `codec:"oom_score_adj"`
 	Runtime                 string             `codec:"runtime"`
 	PidsLimit               int64              `codec:"pids_limit"`
 	PidMode                 string             `codec:"pid_mode"`
@@ -660,6 +669,7 @@ type DriverConfig struct {
 	PullActivityTimeout           string        `codec:"pull_activity_timeout"`
 	PidsLimit                     int64         `codec:"pids_limit"`
 	pullActivityTimeoutDuration   time.Duration `codec:"-"`
+	OOMScoreAdj                   int           `codec:"oom_score_adj"`
 	ExtraLabels                   []string      `codec:"extra_labels"`
 	Logging                       LoggingConfig `codec:"logging"`
 

drivers/docker/config_test.go

@@ -314,6 +314,7 @@ config {
   ]
   network_aliases = ["redis"]
   network_mode = "host"
+  oom_score_adj = 1000
   pids_limit = 2000
 	pid_mode = "host"
 	ports = ["http", "https"]
@@ -475,6 +476,7 @@ config {
 		},
 		NetworkAliases: []string{"redis"},
 		NetworkMode:    "host",
+		OOMScoreAdj:    1000,
 		PidsLimit:      2000,
 		PidMode:        "host",
 		Ports:          []string{"http", "https"},
@@ -720,6 +722,35 @@ func TestConfig_DriverConfig_ContainerExistsAttempts(t *testing.T) {
 	}
 }
 
+func TestConfig_DriverConfig_OOMScoreAdj(t *testing.T) {
+	ci.Parallel(t)
+
+	cases := []struct {
+		name     string
+		config   string
+		expected int
+	}{
+		{
+			name:     "default",
+			config:   `{}`,
+			expected: 0,
+		},
+		{
+			name:     "set explicitly",
+			config:   `{ oom_score_adj = 1001 }`,
+			expected: 1001,
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			var tc DriverConfig
+			hclutils.NewConfigParser(configSpec).ParseHCL(t, "config "+c.config, &tc)
+			must.Eq(t, c.expected, tc.OOMScoreAdj)
+		})
+	}
+}
+
 func TestConfig_DriverConfig_InfraImagePullTimeout(t *testing.T) {
 	ci.Parallel(t)
 

drivers/docker/driver.go

@@ -990,8 +990,9 @@ func (d *Driver) createContainerConfig(task *drivers.TaskConfig, driverConfig *T
 	hostConfig := &docker.HostConfig{
 		// do not set cgroup parent anymore
 
-		Memory:            memory,            // hard limit
+		Memory:            memory,                   // hard limit
-		MemoryReservation: memoryReservation, // soft limit
+		MemoryReservation: memoryReservation,        // soft limit
+		OomScoreAdj:       driverConfig.OOMScoreAdj, // ignored on platforms other than linux
 
 		CPUShares:  task.Resources.LinuxResources.CPUShares,
 		CPUSetCPUs: task.Resources.LinuxResources.CpusetCpus,

website/content/docs/drivers/docker.mdx

@@ -285,6 +285,9 @@ The `docker` driver supports the following configuration in the job spec. Only
   firewalld enabled. This behavior is often caused by the CNI plugin not registering the group
   network as trusted and can be resolved as described in the [network block] documentation.
 
+- `oom_score_adj` - (Optional) A positive integer to indicate the likelihood of
+  the task being OOM killed (valid only for Linux). Defaults to 0.
+
 - `pid_mode` - (Optional) `host` or not set (default). Set to `host` to share
   the PID namespace with the host. Note that this also requires the Nomad agent
   to be configured to allow privileged containers.