docker: support configuring default log driver in plugin options

CHANGELOG.md

@@ -13,6 +13,7 @@ IMPROVEMENTS:
  * cli: Update defaults for `nomad operator debug` flags `-interval` and `-server-id` to match common usage. [[GH-10121](https://github.com/hashicorp/nomad/issues/10121)]
  * consul/connect: Enable setting `local_bind_address` field on connect upstreams [[GH-6248](https://github.com/hashicorp/nomad/issues/6248)]
  * driver/docker: Added support for optional extra container labels. [[GH-9885](https://github.com/hashicorp/nomad/issues/9885)]
+ * driver/docker: Added support for configuring default logger behavior in the client configuration. [[GH-10156](https://github.com/hashicorp/nomad/issues/10156)]
 
 ## 1.0.4 (February 24, 2021)
 

drivers/docker/config.go

@@ -206,6 +206,18 @@ var (
 		// extra docker labels, globs supported
 		"extra_labels": hclspec.NewAttr("extra_labels", "list(string)", false),
 
+		// logging options
+		"logging": hclspec.NewDefault(hclspec.NewBlock("logging", false, hclspec.NewObject(map[string]*hclspec.Spec{
+			"type":   hclspec.NewAttr("type", "string", false),
+			"config": hclspec.NewBlockAttrs("config", "string", false),
+		})), hclspec.NewLiteral(`{
+			type = "json-file" 
+			config = {
+				max-file = "2"
+				max-size = "2m"
+			}
+		}`)),
+
 		// garbage collection options
 		// default needed for both if the gc {...} block is not set and
 		// if the default fields are missing
@@ -616,6 +628,7 @@ type DriverConfig struct {
 	PullActivityTimeout           string        `codec:"pull_activity_timeout"`
 	pullActivityTimeoutDuration   time.Duration `codec:"-"`
 	ExtraLabels                   []string      `codec:"extra_labels"`
+	Logging                       LoggingConfig `codec:"logging"`
 
 	AllowRuntimesList []string            `codec:"allow_runtimes"`
 	allowRuntimes     map[string]struct{} `codec:"-"`
@@ -646,6 +659,11 @@ type VolumeConfig struct {
 	SelinuxLabel string `codec:"selinuxlabel"`
 }
 
+type LoggingConfig struct {
+	Type   string            `codec:"type"`
+	Config map[string]string `codec:"config"`
+}
+
 func (d *Driver) PluginInfo() (*base.PluginInfoResponse, error) {
 	return pluginInfo, nil
 }

drivers/docker/driver.go

@@ -876,12 +876,9 @@ func (d *Driver) createContainerConfig(task *drivers.TaskConfig, driverConfig *T
 	}
 
 	if hostConfig.LogConfig.Type == "" && hostConfig.LogConfig.Config == nil {
-		logger.Trace("no docker log driver provided, defaulting to json-file")
-		hostConfig.LogConfig.Type = "json-file"
-		hostConfig.LogConfig.Config = map[string]string{
-			"max-file": "2",
-			"max-size": "2m",
-		}
+		logger.Trace("no docker log driver provided, defaulting to plugin config")
+		hostConfig.LogConfig.Type = d.config.Logging.Type
+		hostConfig.LogConfig.Config = d.config.Logging.Config
 	}
 
 	logger.Debug("configured resources",

drivers/docker/driver_test.go

@@ -843,6 +843,35 @@ func TestDockerDriver_ExtraLabels(t *testing.T) {
 	}
 }
 
+func TestDockerDriver_LoggingConfiguration(t *testing.T) {
+	if !tu.IsCI() {
+		t.Parallel()
+	}
+	testutil.DockerCompatible(t)
+
+	task, cfg, ports := dockerTask(t)
+	defer freeport.Return(ports)
+
+	require.NoError(t, task.EncodeConcreteDriverConfig(cfg))
+
+	dockerClientConfig := make(map[string]interface{})
+	loggerConfig := map[string]string{"gelf-address": "udp://1.2.3.4:12201", "tag": "gelf"}
+
+	dockerClientConfig["logging"] = LoggingConfig{
+		Type:   "gelf",
+		Config: loggerConfig,
+	}
+	client, d, handle, cleanup := dockerSetup(t, task, dockerClientConfig)
+	defer cleanup()
+	require.NoError(t, d.WaitUntilStarted(task.ID, 5*time.Second))
+
+	container, err := client.InspectContainer(handle.containerID)
+	require.NoError(t, err)
+
+	require.Equal(t, "gelf", container.HostConfig.LogConfig.Type)
+	require.Equal(t, loggerConfig, container.HostConfig.LogConfig.Config)
+}
+
 func TestDockerDriver_ForcePull(t *testing.T) {
 	if !tu.IsCI() {
 		t.Parallel()

website/content/docs/drivers/docker.mdx

@@ -868,10 +868,23 @@ plugin "docker" {
   capabilities and exclusively use host based log aggregation, you may consider
   this option to disable nomad log collection overhead.
 
-- `extra_labels` - Extra labels to add to Docker containers. 
+- `extra_labels` - Extra labels to add to Docker containers.
    Available options are `job_name`, `job_id`, `task_group_name`, `task_name`,
    `namespace`, `node_name`, `node_id`. Globs are supported (e.g. `task*`)
 
+- `logging` stanza:
+
+  - `type` - Defaults to `"json-file"`. Specifies the logging driver docker
+    should use for all containers Nomad starts. Note that for older versions
+    of Docker, only `json-file` file or `journald` will allow Nomad to read
+    the driver's logs via the Docker API, and this will prevent commands such
+    as `nomad alloc logs` from functioning.
+
+  - `config` - Defaults to `{ max-file = "2", max-size = "2m" }`. This option
+    can also be used to pass further
+    [configuration](https://docs.docker.com/config/containers/logging/configure/)
+    to the logging driver.
+
 - `gc` stanza:
 
   - `image` - Defaults to `true`. Changing this to `false` will prevent Nomad