Google now calls Cloud Composer 1 Managed Service for Apache Airflow 129 , with generations named Legacy Gen 1, Gen 2 and Gen 3 (SKUs and images still say composer-3). Gen 3 runs every Airflow component and the Cloud SQL metadata database in a Google-managed tenant project; your project holds only the Cloud Storage bucket for DAGs and logs, plus a VPC network attachment when tasks must reach private hosts. The newest image was composer-3-airflow-3.3.1-build.2 (2 September 2026), but new environments still default to Airflow 2.11.1, so choose 3.x explicitly.
Gen 3 bills Data Compute Units (DCUs), an abstract measure of the vCPU, memory and storage held at each moment: $0.06 per DCU-hour in Iowa ($0.048 with a three-year commitment), covering autoscaled workers, schedulers, DAG processors, triggerers, the web server and the environment size (small, medium or large); Kubernetes 5,150 pods your tasks start count too. Database storage costs about $0.17 per GiB-month from a 10 GiB minimum. Google does not list DCUs per environment size, so estimate with its pricing calculator. For BookNest, whose PostgreSQL 1,289 server sits outside Google Cloud 1 , the real work would be the network path (Securing Orchestration).