Validate GraphQL response on build submission

The GraphQL API does a stricter validation of the manifest then the
Python code, specifically e.g. checking the `oauth:` directive. This can
lead to the API rejecting a manifest that passed the Python validation.
However, for this case, there is currently no error handling, causing
an exception. Such a case has been reported e.g. here: [1]

This commit adds such error handling by passing down the Validation
object all the way to the GraphQL call (which already accepts it). Only
caveat is that in this case, the `field` of the resulting error is not
set to "manifest" (or any other value). Hence, add an additional output
of the manifest summary to the template. This is added near the end of
the form, as we in fact do not know whether the error is from the
manifest, or something else.

[1] https://lists.sr.ht/~sircmpwn/sr.ht-discuss/%3Ce6709b1c-8181-4182-9926-595a38b7bc57%40app.fastmail.com%3E

buildsrht/blueprints/jobs.py

@@ -274,7 +274,9 @@ def submit_POST():
         valid.error(str(ex), field="manifest")
         return render_template("submit.html", **valid.kwargs)
     job_id = submit_build(current_user, _manifest, note=note,
-            visibility=visibility)
+            visibility=visibility, valid=valid)
+    if not valid.ok:
+        return render_template("submit.html", **valid.kwargs)
     return redirect("/~" + current_user.username + "/job/" + str(job_id))
 
 @jobs.route("/cancel/<int:job_id>", methods=["POST"])

buildsrht/runner.py

@@ -22,14 +22,16 @@ runner = Celery('builds', broker=builds_broker, config_source={
 builds_queue_metrics_collector = RedisQueueCollector(builds_broker, "buildsrht_builds", "Number of builds currently in queue")
 builds_submitted = Counter("buildsrht_builds_submitted", "Number of builds submitted")
 
-def submit_build(user, manifest, note=None, tags=[], visibility=None):
+def submit_build(user, manifest, note=None, tags=[], visibility=None, valid=None):
     resp = exec_gql("builds.sr.ht", """
         mutation SubmitBuild($manifest: String!, $tags: [String!], $note: String, $visibility: Visibility) {
             submit(manifest: $manifest, tags: $tags, note: $note, visibility: $visibility) {
                 id
             }
         }
-    """, user=user, manifest=manifest, note=note, tags=tags, visibility=visibility)
+    """, user=user, manifest=manifest, note=note, tags=tags, visibility=visibility, valid=valid)
+    if valid and not valid.ok:
+        return None
     return resp["submit"]["id"]
 
 def requires_payment(user):

buildsrht/templates/submit.html

@@ -110,6 +110,7 @@
         </label>
       </div>
     </fieldset>
+    {{valid.summary()}}
     <div class="form-group">
       <a
         class="pull-right"