以下是一个使用AWS SSM、Auto Scaling Group和负载均衡器的代码示例：

1. 使用AWS SSM存储和获取配置参数：

import boto3

# 创建SSM客户端
ssm_client = boto3.client('ssm')

# 存储配置参数
def put_parameter(parameter_name, parameter_value):
    response = ssm_client.put_parameter(
        Name=parameter_name,
        Value=parameter_value,
        Type='String',
        Overwrite=True
    )
    return response

# 获取配置参数
def get_parameter(parameter_name):
    response = ssm_client.get_parameter(
        Name=parameter_name,
        WithDecryption=False
    )
    value = response['Parameter']['Value']
    return value

# 示例使用
parameter_name = '/myapp/config/database'
parameter_value = 'localhost'
put_parameter(parameter_name, parameter_value)
value = get_parameter(parameter_name)
print(value)

2. 使用Auto Scaling Group自动扩展应用程序：

import boto3

# 创建Auto Scaling客户端
autoscaling_client = boto3.client('autoscaling')

# 创建Auto Scaling组
def create_auto_scaling_group(asg_name, min_size, max_size, desired_capacity, launch_template):
    response = autoscaling_client.create_auto_scaling_group(
        AutoScalingGroupName=asg_name,
        MinSize=min_size,
        MaxSize=max_size,
        DesiredCapacity=desired_capacity,
        LaunchTemplate=launch_template,
        VPCZoneIdentifier='subnet-12345678'  # 替换为你的子网ID
    )
    return response

# 示例使用
asg_name = 'my-asg'
min_size = 2
max_size = 5
desired_capacity = 2
launch_template = {
    'LaunchTemplateId': 'lt-12345678',  # 替换为你的启动模板ID
    'Version': '$Latest'
}
response = create_auto_scaling_group(asg_name, min_size, max_size, desired_capacity, launch_template)
print(response)

3. 使用负载均衡器将流量分配到Auto Scaling组中的实例：

import boto3

# 创建Elastic Load Balancer客户端
elb_client = boto3.client('elbv2')

# 创建负载均衡器
def create_load_balancer(lb_name, subnets, security_groups):
    response = elb_client.create_load_balancer(
        Name=lb_name,
        Subnets=subnets,
        SecurityGroups=security_groups,
        Type='application',
        Scheme='internet-facing'
    )
    return response

# 将目标组与负载均衡器关联
def register_targets(target_group_arn, targets):
    response = elb_client.register_targets(
        TargetGroupArn=target_group_arn,
        Targets=targets
    )
    return response

# 创建监听器
def create_listener(load_balancer_arn, port, target_group_arn):
    response = elb_client.create_listener(
        LoadBalancerArn=load_balancer_arn,
        Protocol='HTTP',
        Port=port,
        DefaultActions=[
            {
                'Type': 'forward',
                'TargetGroupArn': target_group_arn
            }
        ]
    )
    return response

# 示例使用
lb_name = 'my-lb'
subnets = ['subnet-12345678', 'subnet-87654321']  # 替换为你的子网ID
security_groups = ['sg-12345678']  # 替换为你的安全组ID
response = create_load_balancer(lb_name, subnets, security_groups)
print(response)

target_group_arn = 'arn:aws:elasticloadbalancing:us-west-2:123456789012:targetgroup/my-target-group/1234567890'  # 替换为你的目标组ARN
targets = [
    {
        'Id': 'i-12345678',  # 替换为你的实例ID
        'Port': 8080
    }
]
response = register_targets(target_group_arn, targets)
print(response)

load_balancer_arn = response['LoadBalancerArn']
port = 80
response = create_listener(load_balancer_arn, port, target_group_arn)
print(response)

请注意，以上代码示例仅为参考，实际使用时需要根据你的具体情况进行适当的修改和配置。