feat(aws-ecs): Expose logdriver "mode" property (aws#13965)

Closes [aws#13845](aws#13845)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-ecs/README.md

@@ -525,7 +525,7 @@ const taskDefinition = new ecs.Ec2TaskDefinition(this, 'TaskDef');
 taskDefinition.addContainer('TheContainer', {
   image: ecs.ContainerImage.fromAsset(path.resolve(__dirname, '..', 'eventhandler-image')),
   memoryLimitMiB: 256,
-  logging: new ecs.AwsLogDriver({ streamPrefix: 'EventDemo' })
+  logging: new ecs.AwsLogDriver({ streamPrefix: 'EventDemo', mode: AwsLogDriverMode.NON_BLOCKING })
 });
 
 // An Rule that describes the event trigger (in this case a scheduled run)

packages/@aws-cdk/aws-ecs/lib/log-drivers/aws-log-driver.ts

@@ -8,6 +8,23 @@ import { removeEmpty } from './utils';
 // eslint-disable-next-line
 import { Construct as CoreConstruct } from '@aws-cdk/core';
 
+/**
+ * awslogs provides two modes for delivering messages from the container to the log driver
+ */
+export enum AwsLogDriverMode {
+
+  /**
+   * (default) direct, blocking delivery from container to driver.
+   */
+  BLOCKING = 'blocking',
+
+  /**
+   * The non-blocking message delivery mode prevents applications from blocking due to logging back pressure.
+   * Applications are likely to fail in unexpected ways when STDERR or STDOUT streams block.
+   */
+  NON_BLOCKING = 'non-blocking'
+}
+
 /**
  * Specifies the awslogs log driver configuration options.
  */
@@ -62,6 +79,13 @@ export interface AwsLogDriverProps {
    * @default - No multiline matching.
    */
   readonly multilinePattern?: string;
+
+  /**
+   * The delivery mode of log messages from the container to awslogs.
+   *
+   * @default - AwsLogDriverMode.BLOCKING
+   */
+  readonly mode?: AwsLogDriverMode;
 }
 
 /**
@@ -106,6 +130,7 @@ export class AwsLogDriver extends LogDriver {
         'awslogs-region': Stack.of(containerDefinition).region,
         'awslogs-datetime-format': this.props.datetimeFormat,
         'awslogs-multiline-pattern': this.props.multilinePattern,
+        'mode': this.props.mode,
       }),
     };
   }

packages/@aws-cdk/aws-ecs/test/aws-log-driver.test.ts

@@ -25,6 +25,7 @@ nodeunitShim({
         logRetention: logs.RetentionDays.ONE_MONTH,
         multilinePattern: 'pattern',
         streamPrefix: 'hello',
+        mode: ecs.AwsLogDriverMode.NON_BLOCKING,
       }),
     });
 
@@ -44,6 +45,7 @@ nodeunitShim({
               'awslogs-region': { Ref: 'AWS::Region' },
               'awslogs-datetime-format': 'format',
               'awslogs-multiline-pattern': 'pattern',
+              'mode': 'non-blocking',
             },
           },
         },