How to get the log from an application deployed using docker on AWS ecs

You have to create a log group on ECS:

Follow these steps to create your log group-

Step 1: Open the Amazon ECS console at https://console.aws.amazon.com/ecs/.

Step 2: In the left navigation pane, choose Task Definitions, Create new Task Definition.

Step 3: Choose your compatibility option and then Next Step.

Step 4: Choose Add container to begin creating your container definition.

Step 5: In the Storage and Logging section, for Log configuration choose Auto-configure CloudWatch Logs.

Step 6: Enter your awslogs log driver options. For more details, see Specifying a Log Configuration in your Task Definition.

Step 7: Complete the rest of the task definition wizard.

After creating your log view you can see it by using below steps:

Step 1: Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

Step 2: In the navigation pane, choose Logs.

Step 3: For Log Groups, choose the log group to view the streams.

Step 7: For Log Streams, choose the log stream name to view the log data.

For more details:

Working with Log Groups and Log Streams

Using the awslogs Log Driver

In your container definition you need to mention the log configuration. Since Its unclear whether you are creating the ecs cluster using cloudformation / from gui console, I will try to answer for both ways.

1. GUI console:

2. Using cloudformation template:

    {    "containerDefinitions": [        {            "name": "nodejsApplication",            "links": [                "mysql"            ],            "image": "nodejsApplication",            "essential": true,            "portMappings": [                {                    "containerPort": 80,                    "hostPort": 80                }            ],            "logConfiguration": {                "logDriver": "awslogs",                "options": {                    "awslogs-group": "awslogs-nodejsApplication",                    "awslogs-region": "us-west-2",                    "awslogs-stream-prefix": "awslogs-example"                }            },            "memory": 500,            "cpu": 10        }     ]    }

For more details please follow Using Awslogs

console.log prints to STDOUT. A good way to collect this as logs is to use the awslogs log driver. This will route those logs to a CloudWatch Logs stream of your choice. Here is more information on what CloudWatch Logs and how you can use it.