From 525d9d6e113a19faa2ff38b512231b3c1466aa4f Mon Sep 17 00:00:00 2001
From: reivilibre <oliverw@matrix.org>
Date: Mon, 25 Sep 2023 17:59:40 +0100
Subject: [PATCH] Avoid running CI steps when the files they check have not
 been changed. (#14745)

---
 .github/workflows/tests.yml | 96 +++++++++++++++++++++++++++++++------
 changelog.d/14745.misc      |  1 +
 2 files changed, 83 insertions(+), 14 deletions(-)
 create mode 100644 changelog.d/14745.misc

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index fdc79715a..045d3dd25 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -22,6 +22,9 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       rust: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.rust }}
+      trial: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.trial }}
+      integration: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.integration }}
+      linting: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.linting }}
     steps:
     - uses: dorny/paths-filter@v2
       id: filter
@@ -33,9 +36,45 @@ jobs:
             - 'rust/**'
             - 'Cargo.toml'
             - 'Cargo.lock'
+            - '.rustfmt.toml'
+
+          trial:
+            - 'synapse/**'
+            - 'tests/**'
+            - 'rust/**'
+            - 'Cargo.toml'
+            - 'Cargo.lock'
+            - 'pyproject.toml'
+            - 'poetry.lock'
+
+          integration:
+            - 'synapse/**'
+            - 'rust/**'
+            - 'docker/**'
+            - 'Cargo.toml'
+            - 'Cargo.lock'
+            - 'pyproject.toml'
+            - 'poetry.lock'
+            - 'docker/**'
+
+          linting:
+            - 'synapse/**'
+            - 'docker/**'
+            - 'tests/**'
+            - 'scripts-dev/**'
+            - 'contrib/**'
+            - 'synmark/**'
+            - 'stubs/**'
+            - '.ci/**'
+            - 'mypy.ini'
+            - 'pyproject.toml'
+            - 'poetry.lock'
 
   check-sampleconfig:
     runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.linting == 'true' }}
+
     steps:
       - uses: actions/checkout@v4
       - name: Install Rust
@@ -51,6 +90,9 @@ jobs:
 
   check-schema-delta:
     runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.linting == 'true' }}
+
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
@@ -70,6 +112,9 @@ jobs:
 
   lint:
     runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.linting == 'true' }}
+
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -92,6 +137,9 @@ jobs:
   lint-mypy:
     runs-on: ubuntu-latest
     name: Typechecking
+    needs: changes
+    if: ${{ needs.changes.outputs.linting == 'true' }}
+
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -149,6 +197,9 @@ jobs:
 
   lint-pydantic:
     runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.linting == 'true' }}
+
     steps:
       - uses: actions/checkout@v4
         with:
@@ -250,8 +301,10 @@ jobs:
       sytest_test_matrix: ${{ steps.get-matrix.outputs.sytest_test_matrix }}
 
   trial:
-    if: ${{ !cancelled() && !failure() }} # Allow previous steps to be skipped, but not fail
-    needs: calculate-test-jobs
+    if: ${{ !cancelled() && !failure() && needs.changes.outputs.trial == 'true' }} # Allow previous steps to be skipped, but not fail
+    needs:
+      - calculate-test-jobs
+      - changes
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -306,8 +359,10 @@ jobs:
 
   trial-olddeps:
     # Note: sqlite only; no postgres
-    if: ${{ !cancelled() && !failure() }} # Allow previous steps to be skipped, but not fail
-    needs: linting-done
+    if: ${{ !cancelled() && !failure() && needs.changes.outputs.trial == 'true' }} # Allow previous steps to be skipped, but not fail
+    needs:
+      - linting-done
+      - changes
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
@@ -362,8 +417,10 @@ jobs:
   trial-pypy:
     # Very slow; only run if the branch name includes 'pypy'
     # Note: sqlite only; no postgres. Completely untested since poetry move.
-    if: ${{ contains(github.ref, 'pypy') && !failure() && !cancelled() }}
-    needs: linting-done
+    if: ${{ contains(github.ref, 'pypy') && !failure() && !cancelled() && needs.changes.outputs.trial == 'true' }}
+    needs:
+      - linting-done
+      - changes
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -394,8 +451,10 @@ jobs:
           || true
 
   sytest:
-    if: ${{ !failure() && !cancelled() }}
-    needs: calculate-test-jobs
+    if: ${{ !failure() && !cancelled() && needs.changes.outputs.integration == 'true' }}
+    needs:
+      - calculate-test-jobs
+      - changes
     runs-on: ubuntu-latest
     container:
       image: matrixdotorg/sytest-synapse:${{ matrix.job.sytest-tag }}
@@ -476,8 +535,10 @@ jobs:
 
 
   portdb:
-    if: ${{ !failure() && !cancelled() }} # Allow previous steps to be skipped, but not fail
-    needs: linting-done
+    if: ${{ !failure() && !cancelled() && needs.changes.outputs.linting == 'true' }} # Allow previous steps to be skipped, but not fail
+    needs:
+      - linting-done
+      - changes
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -537,8 +598,10 @@ jobs:
             schema_diff
 
   complement:
-    if: "${{ !failure() && !cancelled() }}"
-    needs: linting-done
+    if: "${{ !failure() && !cancelled() && needs.changes.outputs.integration == 'true' }}"
+    needs:
+      - linting-done
+      - changes
     runs-on: ubuntu-latest
 
     strategy:
@@ -632,9 +695,14 @@ jobs:
         with:
           needs: ${{ toJSON(needs) }}
 
-          # The newsfile and signoff lints may be skipped on non PR builds
-          # Cargo test is skipped if there is no changes on Rust code
+          # Various bits are skipped if there was no applicable changes.
+          # The newsfile and signoff lint may be skipped on non PR builds.
           skippable: |
+            trial
+            trial-olddeps
+            sytest
+            portdb
+            complement
             check-signoff
             lint-newsfile
             cargo-test
diff --git a/changelog.d/14745.misc b/changelog.d/14745.misc
new file mode 100644
index 000000000..eae0501d6
--- /dev/null
+++ b/changelog.d/14745.misc
@@ -0,0 +1 @@
+Avoid running CI steps when the files they check have not been changed.
\ No newline at end of file