Amazon ECS Log File in Fargate

As the underlying Platform Version (compute) is fully managed by Fargate, the ECS Agent is not available. Please see the following resources on ECS Fargate container logging options and Observability on ECS/Fargate

ecs-agent.log and ecs-init.log are ECS Agent log files.

You don't need to care about them while using Fargate since it is a managed service.

Regarding the application log, you need to configure the logging driver inside of your task definition.

Also, need to send the application logs to the STDOUT/STDERR. Most of the container images are doing it by default. If you are creating your own image, make sure that the main process is not writing the logs in a file instead.

The logging configuration would be similar to this below:

{
    "containerDefinitions": [
                 (...)
                "logConfiguration": {
                        "logDriver": "awslogs",
                         "options": {
                                "awslogs-create-group": "true",
                                "awslogs-group": "awslogs-mysql",
                                 "awslogs-region": "us-west-2",
                                "awslogs-stream-prefix": "awslogs-example",
                                "mode": "non-blocking", 
                                "max-buffer-size": "25m" 
                }
            (...)

You can find more information about awslogs driver configuration on this documentation.