Monday, November 3, 2025

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Using Cloud Composer to Schedule ML Pipeline Retraining

 Why Automate ML Pipeline Retraining


Machine learning models degrade over time as data distributions change—a phenomenon called model drift. Automating retraining ensures:


Fresh models: Models are updated regularly with the latest data.


Consistency: Standardized preprocessing, training, evaluation, and deployment steps.


Scalability: Pipelines can handle large datasets without manual intervention.


Cloud Composer allows you to schedule and orchestrate these ML workflows in a cloud-native, reproducible way.


๐Ÿ›  Components of an ML Retraining Pipeline


A typical retraining pipeline includes:


Data extraction and preprocessing


Collect new data from databases, storage, or streaming sources.


Perform cleaning, feature engineering, and transformations.


Model training


Train a new model on updated data.


Track hyperparameters, metrics, and artifacts.


Model evaluation


Validate new model against test data.


Compare performance with the currently deployed model.


Model deployment (optional)


If the new model passes evaluation, deploy to production (e.g., Cloud AI Platform, Cloud Functions, or serving endpoints).


Monitoring & alerting


Track model performance over time.


Trigger alerts if retrained models fail evaluation criteria.


๐Ÿ›  Implementing ML Retraining in Cloud Composer

Step 1: Create a DAG

from airflow import DAG

from airflow.utils.dates import days_ago

from airflow.operators.python import PythonOperator


default_args = {

    'owner': 'airflow',

    'depends_on_past': False,

    'retries': 1,

}


with DAG(

    dag_id='ml_pipeline_retraining',

    default_args=default_args,

    start_date=days_ago(1),

    schedule_interval='@weekly',  # Retrain weekly

    catchup=False

) as dag:


    def extract_and_preprocess():

        # Code to fetch new data and preprocess

        print("Extracting and preprocessing data...")


    def train_model():

        # Training code here

        print("Training new ML model...")


    def evaluate_model():

        # Evaluate performance, compare with current model

        print("Evaluating new model...")


    def deploy_model():

        # Deploy if performance is satisfactory

        print("Deploying model to production...")


    t1 = PythonOperator(task_id='extract_preprocess', python_callable=extract_and_preprocess)

    t2 = PythonOperator(task_id='train_model', python_callable=train_model)

    t3 = PythonOperator(task_id='evaluate_model', python_callable=evaluate_model)

    t4 = PythonOperator(task_id='deploy_model', python_callable=deploy_model)


    t1 >> t2 >> t3 >> t4


Step 2: Parameterize DAG for Flexibility


Use Airflow Variables or DAG parameters for:


Data sources or table names


Training hyperparameters


Deployment targets


Example with Variable:


from airflow.models import Variable


data_path = Variable.get("ml_data_path", default_var="gs://my-bucket/data/")


Step 3: Use GCP Services for Scaling


Cloud Storage: Store datasets and model artifacts.


AI Platform / Vertex AI: Train and deploy large models.


BigQuery: Use for feature extraction or large datasets.


Cloud Functions or Cloud Run: Trigger retraining jobs dynamically.


Example: Triggering Vertex AI training job:


from airflow.providers.google.cloud.operators.vertex_ai import (

    VertexAiCustomJobRunOperator

)


train_vertex_job = VertexAiCustomJobRunOperator(

    task_id="vertex_ai_training",

    project_id="my-project",

    location="us-central1",

    body={

        "display_name": "ml_training_job",

        "job_spec": {

            "worker_pool_specs": [

                {

                    "machine_spec": {"machine_type": "n1-standard-4"},

                    "replica_count": 1,

                    "python_package_spec": {

                        "executor_image_uri": "gcr.io/cloud-aiplatform/training/tf-cpu.2-8:latest",

                        "package_uris": ["gs://my-bucket/ml_code.tar.gz"],

                        "python_module": "trainer.task",

                    },

                }

            ]

        },

    }

)


Step 4: Monitoring & Logging


Airflow DAG logs show workflow execution.


Use Vertex AI or Cloud Logging to track model metrics, evaluation, and deployment logs.


Consider adding email or Slack alerts if retraining fails.


Step 5: Best Practices


Schedule retraining frequency wisely


Weekly, daily, or triggered by new data availability.


Avoid retraining too often unless model drift is rapid.


Use versioning for models


Store models with timestamps or version IDs in Cloud Storage or Vertex AI.


Automate evaluation and rollback


Only deploy if the new model improves or maintains performance.


Keep previous model as fallback.


Handle secrets securely


Use Secret Manager for database credentials, API keys, or service account keys.


Test DAG locally or in dev environment


Avoid accidentally retraining in production with untested code.


๐Ÿ“Œ Summary


Cloud Composer enables automated, reproducible ML retraining pipelines.


A typical workflow: extract → preprocess → train → evaluate → deploy → monitor.


Parameterize DAGs, integrate with GCP services (Vertex AI, Cloud Storage, BigQuery), and enforce secure handling of secrets.


Monitoring, evaluation thresholds, and rollback mechanisms are key to safe automation.

Learn GCP Training in Hyderabad

Read More

Automating Cloud Function Deployments with Composer

Managing Secrets in Cloud Composer Workflows

Triggering Cloud Run Jobs from Composer DAGs

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