要解决AWS ECR稳定标签在ECS中不拉取新镜像的问题，可以使用以下代码示例来更新任务定义和服务。

首先，获取最新的镜像标签名称：

import boto3

def get_latest_image_tag(repository_name):
    ecr_client = boto3.client('ecr')
    response = ecr_client.describe_images(
        repositoryName=repository_name,
        filter={
            'tagStatus': 'TAGGED'
        },
        maxResults=1
    )
    latest_image = response['imageDetails'][0]
    return latest_image['imageTags'][0]

然后，更新任务定义并更新服务：

import boto3

def update_task_definition(task_definition_arn, container_name, image_tag):
    ecs_client = boto3.client('ecs')
    response = ecs_client.describe_task_definition(
        taskDefinition=task_definition_arn
    )
    task_definition = response['taskDefinition']

    for container_definition in task_definition['containerDefinitions']:
        if container_definition['name'] == container_name:
            container_definition['image'] = f"{repository_name}:{image_tag}"
            break

    response = ecs_client.register_task_definition(
        family=task_definition['family'],
        containerDefinitions=task_definition['containerDefinitions'],
        taskRoleArn=task_definition['taskRoleArn'],
        executionRoleArn=task_definition['executionRoleArn'],
        networkMode=task_definition['networkMode'],
        requiresCompatibilities=task_definition['requiresCompatibilities'],
        cpu=task_definition['cpu'],
        memory=task_definition['memory']
    )
    new_task_definition_arn = response['taskDefinition']['taskDefinitionArn']
    return new_task_definition_arn

def update_service(service_name, cluster_name, task_definition_arn):
    ecs_client = boto3.client('ecs')
    response = ecs_client.update_service(
        cluster=cluster_name,
        service=service_name,
        taskDefinition=task_definition_arn
    )
    return response

使用这些函数，可以实现在ECS中更新任务定义和服务，以拉取最新的镜像。

repository_name = 'your-ecr-repository-name'
cluster_name = 'your-ecs-cluster-name'
service_name = 'your-ecs-service-name'
container_name = 'your-container-name'

# 获取最新的镜像标签
latest_image_tag = get_latest_image_tag(repository_name)

# 更新任务定义
task_definition_arn = 'your-task-definition-arn'
new_task_definition_arn = update_task_definition(task_definition_arn, container_name, latest_image_tag)

# 更新服务
update_service(service_name, cluster_name, new_task_definition_arn)

请确保在运行代码之前，已经配置了AWS CLI，并具有适当的权限来访问ECR和ECS。