CI: Only run jobs when files changed (#490)

* CI: Only run jobs when files changed

* CI: Comments about why we run tests on main

.github/workflows/ci.yaml

@@ -16,11 +16,48 @@ on:
 
 
 jobs:
+  # JOB to run change detection
+  changes:
+    runs-on: ubuntu-latest
+    # Required permissions
+    permissions:
+      pull-requests: read
+    # Set job outputs to values from filter step
+    outputs:
+      contracts:     ${{ steps.filter.outputs.contracts }}
+      fvm-utils:     ${{ steps.filter.outputs.fvm-utils }}
+      ipc:           ${{ steps.filter.outputs.ipc }}
+      ipld-resolver: ${{ steps.filter.outputs.ipld-resolver }}
+      fendermint:    ${{ steps.filter.outputs.fendermint }}
+    steps:
+      # For pull requests it's not necessary to checkout the code,
+      # but the workflow is also triggered on pushes to `main`.
+      - uses: actions/checkout@v3
+
+      - uses: dorny/paths-filter@v2
+        id: filter
+        with:
+          filters: |
+            contracts:
+              - 'contracts/**'
+            fvm-utils:
+              - 'fvm-utils/**'
+            ipc:
+              - 'ipc/**'
+            ipld-resolver:
+              - 'ipld-resolver/**'
+            fendermint:
+              - 'fendermint/**'
+
   license:
     uses: ./.github/workflows/license.yaml
 
   contracts-prettier:
     uses: ./.github/workflows/contracts-prettier.yaml
+    needs: [changes]
+    if: >-
+      needs.changes.filter.outputs.contracts == 'true' ||
+      github.ref == 'refs/heads/main'
 
   contracts-test:
     uses: ./.github/workflows/contracts-test.yaml
@@ -40,24 +77,44 @@ jobs:
 
   fvm-utils:
     uses: ./.github/workflows/fvm-utils.yaml
-    needs: [license]
+    needs: [changes, license]
+    if: >-
+      needs.changes.filter.outputs.fvm-utils == 'true' ||
+      github.ref == 'refs/heads/main'
 
   ipc:
     uses: ./.github/workflows/ipc.yaml
-    needs: [license]
+    needs: [changes, license]
+    if: >-
+      needs.changes.filter.outputs.contracts == 'true' ||
+      needs.changes.filter.outputs.ipc == 'true' ||
+      github.ref == 'refs/heads/main'
 
   ipld-resolver:
     uses: ./.github/workflows/ipld-resolver.yaml
-    needs: [license]
+    needs: [changes, license]
+    if: >-
+      needs.changes.filter.outputs.ipld-resolver == 'true' ||
+      github.ref == 'refs/heads/main'
 
   fendermint-test:
     uses: ./.github/workflows/fendermint-test.yaml
-    needs: [license]
+    needs: [changes, license]
+    if: >-
+      needs.changes.filter.outputs.contracts == 'true' ||
+      needs.changes.filter.outputs.ipc == 'true' ||
+      needs.changes.filter.outputs.ipld-resolver == 'true' ||
+      needs.changes.filter.outputs.fendermint == 'true' ||
+      github.ref == 'refs/heads/main'
 
   fendermint-publish:
     uses: ./.github/workflows/fendermint-publish.yaml
     secrets: inherit
-    # Dependencies are not strictly necessary, but if fendermint tests pass they publish docker too, so they better work
+    # Dependencies are not strictly necessary, but if fendermint tests pass they publish docker too, so they better work.
+    # It is because of these needs that all the filters are allowed to run on `main` too, otherwise this would be disabled.
+    # It could be done in a more granular approach inside the workflows to allow the job to pass but opt-out of testing,
+    # but I guess it doesn't hurt to run a final round of unconditional tests, even though it takes longer to publish.
+    if: github.ref == 'refs/heads/main'
     needs:
       - contracts-test # generates the ABI artifacts (although fendermint can do on its own too)
       - fvm-utils

.github/workflows/fendermint-publish.yaml

@@ -45,6 +45,12 @@ jobs:
           cache-prefix: publish-${{ hashFiles('rust-toolchain', 'rust-toolchain.toml') }}
           cache-suffix: ${{ hashFiles('**/Cargo.lock') }}
 
+      - name: Cache Solidity ABI arfiacts
+        uses: actions/cache@v2
+        with:
+          path: ./contracts/out
+          key: contracts-abi-${{ hashFiles('./contracts/src/**/*.sol') }}
+
       # - name: Docker Build
       #   run: make docker-build