Accept primary compute spec in /promote, promotion corner cases testing (#12574)

https://github.com/neondatabase/cloud/issues/19011
- Accept `ComputeSpec` in `/promote` instead of just passing safekeepers
and LSN. Update API spec
- Add corner case tests for promotion when promotion or perwarm fails
(using failpoints)
- Print root error for prewarm and promotion in status handlers

compute_tools/src/http/openapi_spec.yaml

@@ -96,7 +96,7 @@ paths:
         content:
           application/json:
             schema:
-                $ref: "#/components/schemas/SafekeepersLsn"
+              $ref: "#/components/schemas/ComputeSchemaWithLsn"
       responses:
         200:
           description: Promote succeeded or wasn't started
@@ -297,14 +297,7 @@ paths:
         content:
           application/json:
             schema:
-              type: object
-              required:
-                - spec
-              properties:
-                spec:
-                  # XXX: I don't want to explain current spec in the OpenAPI format,
-                  # as it could be changed really soon. Consider doing it later.
-                  type: object
+              $ref: "#/components/schemas/ComputeSchema"
       responses:
         200:
           description: Compute configuration finished.
@@ -591,18 +584,25 @@ components:
           type: string
           example: "1.0.0"
 
-    SafekeepersLsn:
+    ComputeSchema:
       type: object
       required:
-        - safekeepers
+        - spec
+      properties:
+        spec:
+          type: object
+    ComputeSchemaWithLsn:
+      type: object
+      required:
+        - spec
         - wal_flush_lsn
       properties:
-        safekeepers:
-          description: Primary replica safekeepers
-          type: string
+        spec:
+          $ref: "#/components/schemas/ComputeState"
         wal_flush_lsn:
-          description: Primary last WAL flush LSN
           type: string
+          description: "last WAL flush LSN"
+          example: "0/028F10D8"
 
     LfcPrewarmState:
       type: object

compute_tools/src/http/routes/promote.rs

@@ -1,14 +1,14 @@
 use crate::http::JsonResponse;
-use axum::Form;
+use axum::extract::Json;
 use http::StatusCode;
 
 pub(in crate::http) async fn promote(
     compute: axum::extract::State<std::sync::Arc<crate::compute::ComputeNode>>,
-    Form(safekeepers_lsn): Form<compute_api::responses::SafekeepersLsn>,
+    Json(cfg): Json<compute_api::responses::PromoteConfig>,
 ) -> axum::response::Response {
-    let state = compute.promote(safekeepers_lsn).await;
-    if let compute_api::responses::PromoteState::Failed { error } = state {
-        return JsonResponse::error(StatusCode::INTERNAL_SERVER_ERROR, error);
+    let state = compute.promote(cfg).await;
+    if let compute_api::responses::PromoteState::Failed { error: _ } = state {
+        return JsonResponse::create_response(StatusCode::INTERNAL_SERVER_ERROR, state);
     }
     JsonResponse::success(StatusCode::OK, state)
 }