API Server and UI

API Server and UI

The API Server and the React UI

Airflow 2 129 's Flask 15,439 "webserver" is gone. Airflow 3's airflow api-server is a FastAPI 36,700 application served by Uvicorn that does three jobs: the public REST API under /api/v2 (v1 was removed), the React 7,897 UI that calls the same API, and the internal Task Execution API under /execution/ that running tasks call (Triggerer and Task Execution). Authentication is pluggable through an auth manager: the default SimpleAuthManager suits development, and the official Compose file installs the Flask AppBuilder (FAB) auth manager from its provider for users and roles. API clients exchange credentials for a JWT and send it as a bearer token:

api.sh: health, a token, and the DAG list over the REST APIShell

B=http://localhost:32880
curl -s $B/api/v2/monitor/health | jq -c '{metadatabase: .metadatabase.status,
  scheduler: .scheduler.status, triggerer: .triggerer.status, dag_processor: .dag_processor.status}'
TOKEN=$(curl -s -X POST $B/auth/token -H 'Content-Type: application/json' \
          -d '{"username": "airflow", "password": "airflow"}' | jq -r .access_token)
curl -s $B/api/v2/version -H "Authorization: Bearer $TOKEN" | jq -c .
curl -s $B/api/v2/dags -H "Authorization: Bearer $TOKEN" \
  | jq -c '.dags[] | {dag_id, is_paused, timetable_summary}'
curl -s -o /dev/null -w 'without a token: HTTP %{http_code}\n' $B/api/v2/dags

Output

{"metadatabase":"healthy","scheduler":"healthy","triggerer":"healthy","dag_processor":"healthy"
  }
{"version":"3.3.2","git_version":".release:aa19d2dbb9ed187ec01957a92848d9b005e9ba9d"}
{"dag_id":"arch_demo","is_paused":true,"timetable_summary":null}
{"dag_id":"booknest_daily","is_paused":true,"timetable_summary":"0 2 * * *"}
without a token: HTTP 401

The health endpoint needs no token, which makes it the right target for load balancer and container health checks. The UI's home page shows the same four health badges:

The Airflow 3.3.2 home page: run statistics, component health and pool slots

The UI is a single-page React application, so any screen you click through can be scripted against /api/v2. API servers are stateless: run two or more behind a load balancer for availability.

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