You are deploying an Apache Airflow directed acyclic graph (DAG) in a Cloud Composer 2 instance. You have incoming files in a Cloud Storage bucket that the DAG processes, one file at a time. The…

Question

Options

• A
  1. Enable Private Google Access in the subnetwork, and set up Cloud Storage notifications to a Pub/Sub topic.
• B
  1. Enable the Cloud Composer API, and set up Cloud Storage notifications to trigger a Cloud Function.
• C
  1. Enable the Airflow REST API, and set up Cloud Storage notifications to trigger a Cloud Function instance.
• D
  1. Enable the Airflow REST API, and set up Cloud Storage notifications to trigger a Cloud Function instance.

• A
  5% (1)
• B
  9% (2)
• C
  82% (18)
• D
  5% (1)

Explanation

Option C is correct because triggering a DAG reactively requires the Airflow REST API (not the Cloud Composer API), which allows external systems to programmatically start a DAG run. A Cloud Function serves as the ideal bridge: Cloud Storage sends a notification when a new file arrives, the Cloud Function is invoked, and it calls the Airflow REST API to trigger the DAG for that specific file.

Why the distractors fail:

• A is wrong because routing notifications to a Pub/Sub topic alone doesn't trigger a DAG - something still needs to consume the message and call the Airflow REST API; Pub/Sub without a downstream trigger is an incomplete solution.
• B is wrong because the Cloud Composer API manages the environment itself (create, update, delete Composer instances) - it cannot trigger individual DAG runs; that's what the Airflow REST API is for.
• D appears identical to C as written, which is likely a question formatting error; in real exam form, D would differ (e.g., a wrong API or trigger mechanism).

Memory tip: Think of it as two distinct APIs - the Cloud Composer API manages the house (the environment), while the Airflow REST API manages the work (the DAGs). Whenever you need to trigger a DAG from outside, always reach for the Airflow REST API + an event-driven intermediary like Cloud Functions.

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