Add dry run for backfill

airflow/api_fastapi/core_api/datamodels/backfills.py

@@ -33,6 +33,7 @@ class BackfillPostBody(BaseModel):
     dag_run_conf: dict = {}
     reprocess_behavior: ReprocessBehavior = ReprocessBehavior.NONE
     max_active_runs: int = 10
+    dry_run: bool = False
 
 
 class BackfillResponse(BaseModel):
@@ -56,3 +57,15 @@ class BackfillCollectionResponse(BaseModel):
 
     backfills: list[BackfillResponse]
     total_entries: int
+
+
+class BackfillRunInfo(BaseModel):
+    """Data model for run information during a backfill operation."""
+
+    logical_date: datetime
+
+
+class BackfillDryRunResponse(BaseModel):
+    """Serializer for responses in dry-run mode for backfill operations."""
+
+    run_info_list: list[BackfillRunInfo]

airflow/api_fastapi/core_api/openapi/v1-generated.yaml

@@ -1143,7 +1143,10 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/BackfillResponse'
+                anyOf:
+                - $ref: '#/components/schemas/BackfillResponse'
+                - $ref: '#/components/schemas/BackfillDryRunResponse'
+                title: Response Create Backfill
         '401':
           content:
             application/json:
@@ -6210,6 +6213,18 @@ components:
       - total_entries
       title: BackfillCollectionResponse
       description: Backfill Collection serializer for responses.
+    BackfillDryRunResponse:
+      properties:
+        run_info_list:
+          items:
+            $ref: '#/components/schemas/BackfillRunInfo'
+          type: array
+          title: Run Info List
+      type: object
+      required:
+      - run_info_list
+      title: BackfillDryRunResponse
+      description: Serializer for responses in dry-run mode for backfill operations.
     BackfillPostBody:
       properties:
         dag_id:
@@ -6238,6 +6253,10 @@ components:
           type: integer
           title: Max Active Runs
           default: 10
+        dry_run:
+          type: boolean
+          title: Dry Run
+          default: false
       type: object
       required:
       - dag_id
@@ -6301,6 +6320,17 @@ components:
       - updated_at
       title: BackfillResponse
       description: Base serializer for Backfill.
+    BackfillRunInfo:
+      properties:
+        logical_date:
+          type: string
+          format: date-time
+          title: Logical Date
+      type: object
+      required:
+      - logical_date
+      title: BackfillRunInfo
+      description: Data model for run information during a backfill operation.
     BaseInfoResponse:
       properties:
         status:

airflow/api_fastapi/core_api/routes/public/backfills.py

@@ -19,7 +19,7 @@
 from typing import Annotated
 
 from fastapi import Depends, HTTPException, status
-from sqlalchemy import select, update
+from sqlalchemy import desc, select, update
 
 from airflow.api_fastapi.common.db.common import (
     AsyncSessionDep,
@@ -30,8 +30,10 @@
 from airflow.api_fastapi.common.router import AirflowRouter
 from airflow.api_fastapi.core_api.datamodels.backfills import (
     BackfillCollectionResponse,
+    BackfillDryRunResponse,
     BackfillPostBody,
     BackfillResponse,
+    BackfillRunInfo,
 )
 from airflow.api_fastapi.core_api.openapi.exceptions import (
     create_openapi_http_exception_doc,
@@ -41,9 +43,14 @@
     AlreadyRunningBackfill,
     Backfill,
     BackfillDagRun,
+    BackfillDagRunExceptionReason,
+    ReprocessBehavior,
     _create_backfill,
+    _get_info_list,
 )
+from airflow.models.serialized_dag import SerializedDagModel
 from airflow.utils import timezone
+from airflow.utils.sqlalchemy import nulls_first
 from airflow.utils.state import DagRunState
 
 backfills_router = AirflowRouter(tags=["Backfill"], prefix="/backfills")
@@ -187,22 +194,62 @@ def cancel_backfill(backfill_id, session: SessionDep) -> BackfillResponse:
 )
 def create_backfill(
     backfill_request: BackfillPostBody,
-) -> BackfillResponse:
+    session: SessionDep,
+) -> BackfillResponse | BackfillDryRunResponse:
     from_date = timezone.coerce_datetime(backfill_request.from_date)
     to_date = timezone.coerce_datetime(backfill_request.to_date)
-    try:
-        backfill_obj = _create_backfill(
-            dag_id=backfill_request.dag_id,
+    if not backfill_request.dry_run:
+        try:
+            backfill_obj = _create_backfill(
+                dag_id=backfill_request.dag_id,
+                from_date=from_date,
+                to_date=to_date,
+                max_active_runs=backfill_request.max_active_runs,
+                reverse=backfill_request.run_backwards,
+                dag_run_conf=backfill_request.dag_run_conf,
+                reprocess_behavior=backfill_request.reprocess_behavior,
+            )
+            return BackfillResponse.model_validate(backfill_obj)
+        except AlreadyRunningBackfill:
+            raise HTTPException(
+                status_code=status.HTTP_409_CONFLICT,
+                detail=f"There is already a running backfill for dag {backfill_request.dag_id}",
+            )
+    else:
+        serdag = session.scalar(SerializedDagModel.latest_item_select_object(backfill_request.dag_id))
+        if not serdag:
+            raise HTTPException(status_code=404, detail=f"Could not find dag {backfill_request.dag_id}")
+
+        info_list = _get_info_list(
+            dag=serdag.dag,
             from_date=from_date,
             to_date=to_date,
-            max_active_runs=backfill_request.max_active_runs,
             reverse=backfill_request.run_backwards,
-            dag_run_conf=backfill_request.dag_run_conf,
-            reprocess_behavior=backfill_request.reprocess_behavior,
-        )
-        return BackfillResponse.model_validate(backfill_obj)
-    except AlreadyRunningBackfill:
-        raise HTTPException(
-            status_code=status.HTTP_409_CONFLICT,
-            detail=f"There is already a running backfill for dag {backfill_request.dag_id}",
         )
+        backfill_response_item = []
+        print(info_list)
+        for info in info_list:
+            print(info.logical_date)
+            dr = session.scalar(
+                select(DagRun)
+                .where(DagRun.logical_date == info.logical_date)
+                .order_by(nulls_first(desc(DagRun.start_date), session))
+                .limit(1)
+            )
+
+            if dr:
+                non_create_reason = None
+                if dr.state not in (DagRunState.SUCCESS, DagRunState.FAILED):
+                    non_create_reason = BackfillDagRunExceptionReason.IN_FLIGHT
+                elif backfill_request.reprocess_behavior is ReprocessBehavior.NONE:
+                    non_create_reason = BackfillDagRunExceptionReason.ALREADY_EXISTS
+                elif backfill_request.reprocess_behavior is ReprocessBehavior.FAILED:
+                    if dr.state != DagRunState.FAILED:
+                        non_create_reason = BackfillDagRunExceptionReason.ALREADY_EXISTS
+                if not non_create_reason:
+                    backfill_response_item.append(BackfillRunInfo(logical_date=info.logical_date))
+
+            else:
+                backfill_response_item.append(BackfillRunInfo(logical_date=info.logical_date))
+
+        return BackfillDryRunResponse(run_info_list=backfill_response_item)

airflow/ui/openapi-gen/queries/queries.ts

@@ -2779,7 +2779,7 @@ export const useAssetServiceCreateAssetEvent = <
  * Create Backfill
  * @param data The data for the request.
  * @param data.requestBody
- * @returns BackfillResponse Successful Response
+ * @returns unknown Successful Response
  * @throws ApiError
  */
 export const useBackfillServiceCreateBackfill = <

airflow/ui/openapi-gen/requests/schemas.gen.ts

@@ -350,6 +350,23 @@ export const $BackfillCollectionResponse = {
   description: "Backfill Collection serializer for responses.",
 } as const;
 
+export const $BackfillDryRunResponse = {
+  properties: {
+    run_info_list: {
+      items: {
+        $ref: "#/components/schemas/BackfillRunInfo",
+      },
+      type: "array",
+      title: "Run Info List",
+    },
+  },
+  type: "object",
+  required: ["run_info_list"],
+  title: "BackfillDryRunResponse",
+  description:
+    "Serializer for responses in dry-run mode for backfill operations.",
+} as const;
+
 export const $BackfillPostBody = {
   properties: {
     dag_id: {
@@ -385,6 +402,11 @@ export const $BackfillPostBody = {
       title: "Max Active Runs",
       default: 10,
     },
+    dry_run: {
+      type: "boolean",
+      title: "Dry Run",
+      default: false,
+    },
   },
   type: "object",
   required: ["dag_id", "from_date", "to_date"],
@@ -468,6 +490,20 @@ export const $BackfillResponse = {
   description: "Base serializer for Backfill.",
 } as const;
 
+export const $BackfillRunInfo = {
+  properties: {
+    logical_date: {
+      type: "string",
+      format: "date-time",
+      title: "Logical Date",
+    },
+  },
+  type: "object",
+  required: ["logical_date"],
+  title: "BackfillRunInfo",
+  description: "Data model for run information during a backfill operation.",
+} as const;
+
 export const $BaseInfoResponse = {
   properties: {
     status: {

airflow/ui/openapi-gen/requests/services.gen.ts

@@ -837,7 +837,7 @@ export class BackfillService {
    * Create Backfill
    * @param data The data for the request.
    * @param data.requestBody
-   * @returns BackfillResponse Successful Response
+   * @returns unknown Successful Response
    * @throws ApiError
    */
   public static createBackfill(

airflow/ui/openapi-gen/requests/types.gen.ts

@@ -97,6 +97,13 @@ export type BackfillCollectionResponse = {
   total_entries: number;
 };
 
+/**
+ * Serializer for responses in dry-run mode for backfill operations.
+ */
+export type BackfillDryRunResponse = {
+  run_info_list: Array<BackfillRunInfo>;
+};
+
 /**
  * Object used for create backfill request.
  */
@@ -110,6 +117,7 @@ export type BackfillPostBody = {
   };
   reprocess_behavior?: ReprocessBehavior;
   max_active_runs?: number;
+  dry_run?: boolean;
 };
 
 /**
@@ -131,6 +139,13 @@ export type BackfillResponse = {
   updated_at: string;
 };
 
+/**
+ * Data model for run information during a backfill operation.
+ */
+export type BackfillRunInfo = {
+  logical_date: string;
+};
+
 /**
  * Base info serializer for responses.
  */
@@ -1498,7 +1513,7 @@ export type CreateBackfillData = {
   requestBody: BackfillPostBody;
 };
 
-export type CreateBackfillResponse = BackfillResponse;
+export type CreateBackfillResponse = BackfillResponse | BackfillDryRunResponse;
 
 export type GetBackfillData = {
   backfillId: string;
@@ -2630,7 +2645,7 @@ export type $OpenApiTs = {
         /**
          * Successful Response
          */
-        200: BackfillResponse;
+        200: BackfillResponse | BackfillDryRunResponse;
         /**
          * Unauthorized
          */

tests/api_fastapi/core_api/routes/public/test_backfills.py

@@ -192,6 +192,7 @@ def test_create_backfill(self, repro_act, repro_exp, session, dag_maker, test_cl
             "max_active_runs": max_active_runs,
             "run_backwards": False,
             "dag_run_conf": {"param1": "val1", "param2": True},
+            "dry_run": False,
         }
         if repro_act is not None:
             data["reprocess_behavior"] = repro_act