Increase infra_fail_job_index limit.

Summary:
Arguably should be using `paginate`, but that'd require a schema/UI change, and
this is very easy.

Test Plan: None

Reviewers: naphat

Reviewed By: naphat

Subscribers: changesbot, anupc

Differential Revision: https://tails.corp.dropbox.com/D231183

changes/api/infra_fail_job_index.py

@@ -1,26 +1,34 @@
 from __future__ import absolute_import
 
+from flask.ext.restful import reqparse
 from sqlalchemy.orm import joinedload
 from datetime import datetime, timedelta
 
 from changes.api.base import APIView
 from changes.api.serializer.models.job import JobWithBuildCrumbler
+from changes.api.validators.basic import bounded_integer
 from changes.constants import Result
 from changes.models.job import Job
 
 
 class InfraFailJobIndexAPIView(APIView):
     """Defines the endpoint for fetching jobs that recently failed for infrastructural reasons."""
 
+    get_parser = reqparse.RequestParser()
+    get_parser.add_argument('limit', type=bounded_integer(0, 1000), location='args',
+                            default=250)
+
     def get(self):
+        args = self.get_parser.parse_args()
+
         jobs = Job.query.options(
             joinedload(Job.build, innerjoin=True),
         ).filter(
             Job.result == Result.infra_failed,
             # Only last 24 hours so that a non-empty view can be a matter for concern.
             Job.date_created >= datetime.utcnow() - timedelta(hours=24),
         ).order_by(Job.date_created.desc()
-        ).limit(50)  # fairly arbitrary limit
+        ).limit(args.limit)
 
         result = {
             'recent': list(jobs),

changes/api/validators/basic.py

@@ -0,0 +1,13 @@
+from typing import Callable  # NOQA
+
+
+def bounded_integer(lower, upper):
+    """Accepts an integer in [lower, upper]."""
+    # type: (int, int) -> Callable[str, int]
+    def parse(s):
+        # type: (str) -> int
+        iv = int(s)
+        if iv < lower or iv > upper:
+            raise ValueError("{} is not in [{}, {}]".format(iv, lower, upper))
+        return iv
+    return parse

tests/changes/api/validators/test_basic.py

@@ -0,0 +1,26 @@
+import pytest
+from changes.api.validators.basic import bounded_integer
+
+
+def test_bounded_integer():
+    validator = bounded_integer(0, 10)
+    with pytest.raises(ValueError):
+        validator("11")
+
+    with pytest.raises(ValueError):
+        validator("4.5")
+
+    with pytest.raises(ValueError):
+        validator("-3")
+
+    with pytest.raises(ValueError):
+        validator("")
+
+    with pytest.raises(ValueError):
+        validator("10000")
+
+    # No error expeceted
+    validator("0")
+    validator("2")
+    validator("9")
+    validator("10")