workflows: use artifacts in pull request

.github/workflows/run-network-tests-pull-request.yml

@@ -4,12 +4,12 @@ on:
     types: [labeled, synchronize]
 
 jobs:
-  run_network_tests:
-    name: Network Integration Tests (pull request)
+  prepare_docker_images:
+    name: Prepare joystream/node docker image
     if: contains(github.event.pull_request.labels.*.name, 'run-network-tests')
     runs-on: ubuntu-latest
-    env:
-      JOYSTREAM_NODE_TAG: ${{ github.event.pull_request.base.ref }}
+    outputs:
+      runtime_code_shasum: ${{ steps.compute_shasum.outputs.shasum }}
     steps:
       - uses: actions/checkout@v1
       - uses: actions/setup-node@v1
@@ -26,17 +26,69 @@ jobs:
           FILES: |
             Cargo.lock
             Cargo.toml
+  
+      - id: compute_shasum
+        name: Compute runtime code shasum
+        run: |
+          export RUNTIME_CODE_SHASUM=`tar -c runtime runtime-modules utils/chain-spec-builder | shasum | cut -d " " -f 1`
+          echo "::set-output name=shasum::${RUNTIME_CODE_SHASUM}"
+        if: env.GIT_DIFF
+
+      - name: Check if we have a pre-built image
+        continue-on-error: true
+        uses: actions/download-artifact@v2
+        with:
+          name: ${{ steps.compute_shasum.outputs.shasum }}-test
+        if: env.GIT_DIFF
+
+      - name: Build new image (if fetching artifact failed)
+        run: |
+            echo "${{ steps.compute_shasum.outputs.shasum }}" > shasum.txt
+        if: env.GIT_DIFF && ${{ failure() }}
+
+      - name: Upload new image
+        uses: actions/upload-artifact@v2
+        with:
+          name: ${{ steps.compute_shasum.outputs.shasum }}-test
+          path: shasum.txt
+        if: env.GIT_DIFF && ${{ success()) }}
+
+  network_tests_1:
+    name: Network Integration Tests (pull request)
+    needs: prepare_docker_images
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions/setup-node@v1
+        with:
+          node-version: '12.x'
+
+      - name: Download Pre-built artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: ${{ needs.prepare_docker_images.outputs.runtime_code_shasum }}-test
+        if: ${{ needs.prepare_docker_images.outputs.runtime_code_shasum }}
+
+      - name: Install artifact
+        run: cat shasum.txt
+        if: ${{ needs.prepare_docker_images.outputs.runtime_code_shasum }}
+
+      - name: Pull joystream/node image for base branch from Dockerhub
+        run: |
+            export JOYSTREAM_NODE_TAG=${{ github.event.pull_request.base.ref }}
+            docker-compose pull
+            docker image tag joystream/node:${JOYSTREAM_NODE_TAG} joystream/node:latest
+        if: ${{ needs.prepare_docker_images.outputs.runtime_code_shasum }} == ''
+
       - name: Install packages and dependencies
         run: yarn install --frozen-lockfile
+
       - name: Ensure tests are runnable
         run: yarn workspace network-tests build
-      - name: Build joystream/node Docker image from source
-        run: docker-compose build
-        if: env.GIT_DIFF
-      - name: Pull joystream/node image from Dockerhub
-        run: docker-compose pull
-        if: env.GIT_DIFF == ''
+
       - name: Start chain
-        run: docker-compose up -d
+        run: docker-compose up -d --no-build
+
       - name: Execute network tests
         run: yarn workspace network-tests test
+