feat(backup): Generate validation run cloudbuild.yaml (#59372)

This file instruments the validation run we need to perform before we
can kick off the actual relocation. We build a bespoke YAML for each
such run, rather than using substitutions, as there is enough
variability that this ends up a bit easier to read, and some variables
could grow longer than the substitution API is willing to accept.

Issue: getsentry/team-ospo#203

src/sentry/models/relocation.py

@@ -161,18 +161,21 @@ class Kind(Enum):
         def get_choices(cls) -> list[tuple[int, str]]:
             return [(key.value, key.name) for key in cls]
 
-        def to_filename(self, suffix: str):
+        def __str__(self):
             if self.name == "RAW_USER_DATA":
-                return f"raw-relocation-data.{suffix}"
+                return "raw-relocation-data"
             elif self.name == "NORMALIZED_USER_DATA":
-                return f"normalized-relocation-data.{suffix}"
+                return "normalized-relocation-data"
             elif self.name == "BASELINE_CONFIG_VALIDATION_DATA":
-                return f"baseline-config.{suffix}"
+                return "baseline-config"
             elif self.name == "COLLIDING_USERS_VALIDATION_DATA":
-                return f"colliding-users.{suffix}"
+                return "colliding-users"
             else:
                 raise ValueError("Cannot extract a filename from `RelocationFile.Kind.UNKNOWN`.")
 
+        def to_filename(self, ext: str):
+            return str(self) + "." + ext
+
     relocation = FlexibleForeignKey("sentry.Relocation")
     file = FlexibleForeignKey("sentry.File")
     kind = models.SmallIntegerField(choices=Kind.get_choices())

src/sentry/tasks/relocation.py

@@ -28,6 +28,7 @@
     RELOCATION_BLOB_SIZE,
     RELOCATION_FILE_TYPE,
     OrderedTask,
+    create_cloudbuild_yaml,
     fail_relocation,
     retry_task_or_fail_relocation,
     start_relocation_task,
@@ -418,6 +419,17 @@ def preprocessing_complete(uuid: str) -> None:
         ERR_PREPROCESSING_INTERNAL,
     ):
         storage = get_storage()
+
+        # Build the `cloudbuild.yaml` file we'll use for validation.
+        cloudbuild_yaml = create_cloudbuild_yaml(relocation)
+        storage.save(f"relocations/runs/{uuid}/conf/cloudbuild.yaml", BytesIO(cloudbuild_yaml))
+
+        # Upload the `key-config.json` file we'll use to identify the correct KMS resource use
+        # during validation.
+        kms_config_bytes = json.dumps(DEFAULT_CRYPTO_KEY_VERSION).encode("utf-8")
+        storage.save(f"relocations/runs/{uuid}/in/kms-config.json", BytesIO(kms_config_bytes))
+
+        # Upload the exports we'll be validating.
         for kind in RELOCATION_FILES_TO_BE_VALIDATED:
             raw_relocation_file = (
                 RelocationFile.objects.filter(