初期構築

docker-compose.yaml

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+# prefect-template/docker-compose.yml
+services:
+  server:
+    image: prefecthq/prefect:2-latest
+    container_name: prefect-server
+    command: ["prefect","server","start","--host","0.0.0.0"]
+    ports: ["4200:4200"]       # UI: http://localhost:4200
+    environment:
+      PREFECT_UI_URL: "http://localhost:4200"
+      PREFECT_API_URL: "http://server:4200/api"
+      TZ: "Asia/Tokyo"
+      # Slack通知を使う場合、.env で SLACK_WEBHOOK_URL を設定
+      SLACK_WEBHOOK_URL: ${SLACK_WEBHOOK_URL:-}
+    volumes:
+      - ./src/flows:/opt/flows
+      - prefect-data:/root/.prefect
+
+  worker:
+    image: prefecthq/prefect:2-latest
+    container_name: prefect-worker
+    depends_on: [server]
+    environment:
+      PREFECT_API_URL: "http://server:4200/api"
+      TZ: "Asia/Tokyo"
+      SLACK_WEBHOOK_URL: ${SLACK_WEBHOOK_URL:-}
+    volumes:
+      - ./src/flows:/opt/flows
+    command: >
+      bash -lc "
+      pip install -r /opt/flows/requirements.txt >/dev/null 2>&1 || true &&
+      prefect work-pool create process-pool -t process || true &&
+      prefect worker start -p process-pool
+      "
+
+volumes:
+  prefect-data:

requirements.txt

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+requests
+prefect

src/flows/etl_flow.py

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+from prefect import flow, task
+from datetime import date
+
+@task(retries=3, retry_delay_seconds=10)
+def extract(d): return f"raw({d})"
+
+@task
+def transform(raw): return raw.replace("raw","clean")
+
+@task
+def load(clean): print(f"loaded: {clean}")
+
+@flow
+def etl_flow(d: str | None = None):
+    d = d or date.today().isoformat()
+    load(transform(extract(d)))
+
+if __name__ == "__main__":
+    etl_flow()