Reduce number of CI jobs run on PRs (#13713)

* Reduce number of CI jobs run on PRs

* Newsfile

* Also limit sytest jobs

* Fix typo

* Fix up

* Fixup

.ci/scripts/calculate_jobs.py

@@ -0,0 +1,128 @@
+#!/usr/bin/env python
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Calculate the trial jobs to run based on if we're in a PR or not.
+
+import json
+import os
+
+IS_PR = os.environ["GITHUB_REF"].startswith("refs/pull/")
+
+# First calculate the various trial jobs.
+#
+# For each type of test we only run on Py3.7 on PRs
+
+trial_sqlite_tests = [
+    {
+        "python-version": "3.7",
+        "database": "sqlite",
+        "extras": "all",
+    }
+]
+
+if not IS_PR:
+    trial_sqlite_tests.extend(
+        {
+            "python-version": version,
+            "database": "sqlite",
+            "extras": "all",
+        }
+        for version in ("3.8", "3.9", "3.10")
+    )
+
+
+trial_postgres_tests = [
+    {
+        "python-version": "3.7",
+        "database": "postgres",
+        "postgres-version": "10",
+        "extras": "all",
+    }
+]
+
+if not IS_PR:
+    trial_postgres_tests.append(
+        {
+            "python-version": "3.10",
+            "database": "postgres",
+            "postgres-version": "14",
+            "extras": "all",
+        }
+    )
+
+trial_no_extra_tests = [
+    {
+        "python-version": "3.7",
+        "database": "sqlite",
+        "extras": "",
+    }
+]
+
+print("::group::Calculated trial jobs")
+print(
+    json.dumps(
+        trial_sqlite_tests + trial_postgres_tests + trial_no_extra_tests, indent=4
+    )
+)
+print("::endgroup::")
+
+test_matrix = json.dumps(
+    trial_sqlite_tests + trial_postgres_tests + trial_no_extra_tests
+)
+print(f"::set-output name=trial_test_matrix::{test_matrix}")
+
+
+# First calculate the various sytest jobs.
+#
+# For each type of test we only run on focal on PRs
+
+
+sytest_tests = [
+    {
+        "sytest-tag": "focal",
+    },
+    {
+        "sytest-tag": "focal",
+        "postgres": "postgres",
+    },
+    {
+        "sytest-tag": "focal",
+        "postgres": "multi-postgres",
+        "workers": "workers",
+    },
+]
+
+if not IS_PR:
+    sytest_tests.extend(
+        [
+            {
+                "sytest-tag": "testing",
+                "postgres": "postgres",
+            },
+            {
+                "sytest-tag": "buster",
+                "postgres": "multi-postgres",
+                "workers": "workers",
+            },
+        ]
+    )
+
+
+print("::group::Calculated sytest jobs")
+print(json.dumps(sytest_tests, indent=4))
+print("::endgroup::")
+
+test_matrix = json.dumps(sytest_tests)
+print(f"::set-output name=sytest_test_matrix::{test_matrix}")