下面是一个使用ALB、Nginx和Fargate创建负载均衡器的解决方案，包含了代码示例：

1. 创建一个ECS集群：

aws ecs create-cluster --cluster-name my-cluster

2. 创建一个IAM角色，用于给ECS服务和任务分配所需的权限：

aws iam create-role --role-name ecsTaskExecutionRole --assume-role-policy-document '{"Version": "2012-10-17","Statement": [{"Effect": "Allow","Principal": {"Service": "ecs-tasks.amazonaws.com"},"Action": "sts:AssumeRole"}]}'
aws iam attach-role-policy --role-name ecsTaskExecutionRole --policy-arn arn:aws:iam::aws:policy/service-role/AmazonECSTaskExecutionRolePolicy

3. 创建一个ECS任务定义，其中包含了容器化的Nginx服务：

aws ecs register-task-definition \
    --family my-task \
    --task-role-arn arn:aws:iam::0123456789012:role/ecsTaskExecutionRole \
    --network-mode awsvpc \
    --execution-role-arn arn:aws:iam::0123456789012:role/ecsTaskExecutionRole \
    --container-definitions '[{"name": "nginx","image": "nginx","portMappings": [{"containerPort": 80,"protocol": "tcp"}],"essential": true,"logConfiguration": {"logDriver": "awslogs","options": {"awslogs-group": "/ecs/nginx","awslogs-region": "us-west-2","awslogs-stream-prefix": "ecs"}}}]'

4. 创建一个ALB并配置目标组：

aws elbv2 create-load-balancer \
    --name my-load-balancer \
    --subnets subnet-01234567890abcdef subnet-01234567890abcdef \
    --security-groups sg-01234567890abcdef

5. 创建一个目标组，并将其与ECS服务关联：

aws elbv2 create-target-group \
    --name my-target-group \
    --protocol HTTP \
    --port 80 \
    --vpc-id vpc-01234567890abcdef
aws ecs create-service \
    --cluster my-cluster \
    --service-name my-service \
    --task-definition my-task \
    --desired-count 2 \
    --network-configuration 'awsvpcConfiguration={subnets=[subnet-01234567890abcdef,subnet-01234567890abcdef],securityGroups=[sg-01234567890abcdef],assignPublicIp=ENABLED}' \
    --load-balancers targetGroupArn=arn:aws:elasticloadbalancing:us-west-2:0123456789012:targetgroup/my-target-group/01234567890abcdef

这样，你就创建了一个使用ALB、Nginx和Fargate的负载均衡器。