ALB is failing and killing the Fargate service task stating it's unhealthy

I have deployed a Fargate service for my app and attached ALB to it ,it's giving an health status as unhealthy and killing the task and restarting the task. It's throwing below error -

service myapp-service port 8080 is unhealthy in target-group MyServiceTargetGroup  due to (reason Health checks failed with these codes: [404]).

In my security group settings i have allowed all traffic for port 8080 My sample app path when i run in local is - http://000.00.0.00:8080/myapp

Below is the cloudformation template i used for deployment

Resources:
  Cluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: !Join ['', [!Ref ServiceName, Cluster]]

  TaskDefinition:
    Type: AWS::ECS::TaskDefinition
    Properties:
      NetworkMode: awsvpc
      RequiresCompatibilities:
        - FARGATE
      Cpu: '4096'
      Memory: '16384'

      ExecutionRoleArn: !GetAtt ExecutionRole.Arn
      TaskRoleArn: !GetAtt TaskRole.Arn
      ContainerDefinitions:
        - Name: !Ref ServiceName
          Image: !Ref Image
          PortMappings:
            - ContainerPort: !Ref ContainerPort
          Essential: true
      EphemeralStorage:
        SizeInGiB: 150

  ExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: myappExecutionRole
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: ecs-tasks.amazonaws.com
            Action: 'sts:AssumeRole'
      ManagedPolicyArns:
        - 'arn:aws:iam::aws:policy/service-role/AmazonECSTaskExecutionRolePolicy'

  TaskRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: myappTaskRole
      AssumeRolePolicyDocument:
        Statement:
          - Effect: Allow
            Principal:
              Service: ecs-tasks.amazonaws.com
            Action: 'sts:AssumeRole'
  
  FargateService:
    Type: AWS::ECS::Service
    Properties:
      Cluster: !Ref Cluster
      LaunchType: FARGATE
      ServiceName: mudetect-service
      DesiredCount: 1
      TaskDefinition: !Ref TaskDefinition
      LoadBalancers:
        - ContainerName: !Ref ServiceName
          ContainerPort: !Ref ContainerPort
          TargetGroupArn: !Ref TargetGroup
      NetworkConfiguration:
        AwsvpcConfiguration:
          AssignPublicIp: ENABLED
          SecurityGroups:
            - !Ref SecurityGroup
          Subnets:
            - !Ref SubnetA
            - !Ref SubnetB
      DeploymentConfiguration:
        MaximumPercent: 200
        MinimumHealthyPercent: 100
        DeploymentCircuitBreaker:
          Enable: true
          Rollback: true

  LoadBalancer:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Properties:
      Name: !Join ['', [!Ref ServiceName, LoadBalancer]]
      Type: application
      Subnets:
        - !Ref SubnetA
        - !Ref SubnetB
      SecurityGroups:
        - !Ref SecurityGroup

  TargetGroup:
    Type: AWS::ElasticLoadBalancingV2::TargetGroup
    Properties:
      HealthCheckPath: /
      Name: !Join ['', [!Ref ServiceName, TargetGroup]]
      Port: !Ref ContainerPort
      Protocol: HTTP
      VpcId: !Ref VPC
      HealthCheckProtocol: HTTP
      TargetType: ip
      LoadBalancerArns:
        - !Ref LoadBalancer


  Listener:
    Type: AWS::ElasticLoadBalancingV2::Listener
    Properties:
      DefaultActions:
        - Type: forward
          TargetGroupArn: !Ref TargetGroup
      LoadBalancerArn: !Ref LoadBalancer
      Port: 8080
      Protocol: HTTP