在Airflow中,您可以使用Boto3库来操作AWS EMR集群。以下是一个解决方案的示例代码,用于确保EMR集群启动后再运行任务:
import boto3
from airflow.providers.amazon.aws.hooks.emr import EmrHook
from airflow.models import DAG
from airflow.operators.python_operator import PythonOperator
from datetime import datetime
import time
# 创建一个DAG
dag = DAG('emr_task_dag', start_date=datetime(2022, 1, 1), schedule_interval=None)
# 定义一个函数来启动EMR集群并等待集群启动完成
def start_emr_cluster():
# 创建EMR连接
emr_hook = EmrHook(aws_conn_id='aws_default')
# 启动EMR集群
cluster_id = emr_hook.create_cluster(
Name='my_emr_cluster',
ReleaseLabel='emr-6.5.0',
Instances={
'InstanceGroups': [
{
'Name': 'Master node',
'Market': 'SPOT',
'InstanceRole': 'MASTER',
'InstanceType': 'm5.xlarge',
'InstanceCount': 1,
},
{
'Name': 'Core nodes',
'Market': 'SPOT',
'InstanceRole': 'CORE',
'InstanceType': 'm5.xlarge',
'InstanceCount': 2,
}
],
'KeepJobFlowAliveWhenNoSteps': True,
'TerminationProtected': False,
'Ec2KeyName': 'my_ec2_key',
},
Applications=[
{'Name': 'Spark'},
],
VisibleToAllUsers=True,
JobFlowRole='EMR_EC2_DefaultRole',
ServiceRole='EMR_DefaultRole',
)
# 等待集群启动完成
while True:
cluster_status = emr_hook.describe_cluster(ClusterId=cluster_id)['Cluster']['Status']['State']
if cluster_status in ['RUNNING', 'WAITING']:
break
time.sleep(60) # 每隔60秒检查一次集群状态
return cluster_id
# 定义一个函数来运行任务
def run_task():
# 创建EMR连接
emr_hook = EmrHook(aws_conn_id='aws_default')
# 运行任务
emr_hook.run_job_flow_steps(
JobFlowId='my_emr_cluster', # 替换为实际的EMR集群ID
Steps=[
{
'Name': 'My Spark Job',
'ActionOnFailure': 'CONTINUE',
'HadoopJarStep': {
'Jar': 'command-runner.jar',
'Args': ['spark-submit', '--class', 'com.example.MySparkJob', 's3://my-bucket/my-spark-job.jar'],
},
},
],
)
# 创建任务运行的PythonOperator
start_cluster_operator = PythonOperator(
task_id='start_emr_cluster',
python_callable=start_emr_cluster,
dag=dag,
)
run_task_operator = PythonOperator(
task_id='run_task',
python_callable=run_task,
dag=dag,
)
# 设置任务依赖关系
start_cluster_operator >> run_task_operator
在上述示例代码中,我们通过EmrHook
来创建EMR集群并等待集群启动完成。start_emr_cluster
函数将返回启动的EMR集群ID,然后可以将其用于运行任务。run_task
函数使用run_job_flow_steps
方法来运行任务。
将上述代码保存为Airflow的DAG文件,然后在Airflow的Web界面中启动该DAG,即可实现EMR任务成功但集群未启动的解决方案。