[Core-249] Compute: Credentials checking (#12420)

GitOrigin-RevId: 2c13397cc5eb62d39576cb283cc0be413514108e

README.md

@@ -51,6 +51,8 @@ Changelog
 - The efficiency of deleting many jobs at once has been significantly improved using `Function.delete` and
   `Function.delete_jobs`. It is still possible to encounter request timeouts with very large numbers of jobs;
   workarounds are now documented in the API documentation for the `Function.delete_jobs` method.
+- The `ComputeClient.check_credentials` method has been added, so that the client can determine if valid
+  user credentials have already been registered with the Compute service.
 
 ### Vector
 

descarteslabs/core/compute/compute_client.py

@@ -58,14 +58,25 @@ def iter_log_lines(self, url: str, timestamps: bool = True) -> Iterator[str]:
 
             yield log
 
+    def check_credentials(self):
+        """Determine if valid credentials are already set for the user."""
+        _ = self.session.get("/credentials")
+
     def set_credentials(self):
-        self.session.post(
-            "/credentials",
-            json={
-                "client_id": self.auth.client_id,
-                "client_secret": self.auth.client_secret,
-            },
-        )
+        if self.auth.client_id and self.auth.client_secret:
+            self.session.post(
+                "/credentials",
+                json={
+                    "client_id": self.auth.client_id,
+                    "client_secret": self.auth.client_secret,
+                },
+            )
+        else:
+            # We only have a JWT and no client id/secret, so validate
+            # that there are already valid credentials set for the user.
+            # This situation will generally only arise when used from
+            # some backend process.
+            self.check_credentials()
 
     def get_namespace(self, function_id: str) -> Optional[str]:
         if function_id in self._namespace_cache: