add 'none' logging driver ECS Agent's config

This commit modifies the `ECS_AVAILABLE_LOGGING_DRIVERS` env var
for the Agent to include `none` logging driver. This compliments
aws/amazon-ecs-agent#1041 PR in the
ECS Agent repository.

Author: aaithal

ecs-init/docker/docker.go

@@ -196,7 +196,7 @@ func (c *Client) getContainerConfig() *godocker.Config {
 		"ECS_AGENT_CONFIG_FILE_PATH":            config.AgentJSONConfigFile(),
 		"ECS_UPDATE_DOWNLOAD_DIR":               config.CacheDirectory(),
 		"ECS_UPDATES_ENABLED":                   "true",
-		"ECS_AVAILABLE_LOGGING_DRIVERS":         `["json-file","syslog","awslogs"]`,
+		"ECS_AVAILABLE_LOGGING_DRIVERS":         `["json-file","syslog","awslogs","none"]`,
 		"ECS_ENABLE_TASK_IAM_ROLE":              "true",
 		"ECS_ENABLE_TASK_IAM_ROLE_NETWORK_HOST": "true",
 	}

ecs-init/docker/docker_test.go

@@ -224,7 +224,8 @@ func validateCommonCreateContainerOptions(opts godocker.CreateContainerOptions,
 	expectKey("ECS_AGENT_CONFIG_FILE_PATH="+config.AgentJSONConfigFile(), envVariables, t)
 	expectKey("ECS_UPDATE_DOWNLOAD_DIR="+config.CacheDirectory(), envVariables, t)
 	expectKey("ECS_UPDATES_ENABLED=true", envVariables, t)
-	expectKey(`ECS_AVAILABLE_LOGGING_DRIVERS=["json-file","syslog","awslogs"]`, envVariables, t)
+	expectKey(`ECS_AVAILABLE_LOGGING_DRIVERS=["json-file","syslog","awslogs","none"]`,
+		envVariables, t)
 	expectKey("ECS_ENABLE_TASK_IAM_ROLE=true", envVariables, t)
 	expectKey("ECS_ENABLE_TASK_IAM_ROLE_NETWORK_HOST=true", envVariables, t)
 	expectKey("ECS_ENABLE_TASK_ENI=true", envVariables, t)