feat: add enough configuration to use self-hosted runners

.github/workflows/build.yml

@@ -29,10 +29,47 @@ on:
       SSH_PRIVATE_KEY:
         description: 'Service user SSH key for repository checkout'
         required: true
+      GH_PERSONAL_ACCESS_TOKEN:
+        description: 'GitHub personal access token'
+        required: true
+      AWS_ACCESS_KEY_ID:
+        description: 'AWS access key ID'
+        required: true
+      AWS_SECRET_ACCESS_KEY:
+        description: 'AWS secret access key'
+        required: true
+      AWS_REGION:
+        description: 'AWS region'
+        required: true
 
 jobs:
-  build:
+  start-runner:
+    name: Start self-hosted EC2 runner
     runs-on: ubuntu-latest
+    outputs:
+      label: ${{ steps.start-ec2-runner.outputs.label }}
+      ec2-instance-id: ${{ steps.start-ec2-runner.outputs.ec2-instance-id }}
+    steps:
+      - name: Configure AWS credentials
+        uses: aws-actions/configure-aws-credentials@v1
+        with:
+          aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          aws-region: ${{ secrets.AWS_REGION }}
+      - name: Start EC2 runner
+        id: start-ec2-runner
+        uses: machulav/ec2-github-runner@v2
+        with:
+          mode: start
+          github-token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }}
+          ec2-image-id: ami-06298721653b69e45
+          ec2-instance-type: m6i.2xlarge
+          subnet-id: subnet-08912dcec955b1bd9
+          security-group-id: sg-0d76181fdee037a27
+  build:
+    name: Build service image
+    needs: start-runner
+    runs-on: ${{ needs.start-runner.outputs.label }}
 
     steps:
       - name: Login to DockerHub
@@ -169,3 +206,25 @@ jobs:
         run: |
           . .tvm/bin/activate
           tutor images push $SERVICE
+
+  stop-runner:
+    name: Stop self-hosted EC2 runner
+    needs:
+      - start-runner # required to get output from the start-runner job
+      - build # required to wait when the main job is done
+    runs-on: ubuntu-latest
+    if: ${{ always() }}
+    steps:
+      - name: Configure AWS credentials
+        uses: aws-actions/configure-aws-credentials@v1
+        with:
+          aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
+          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          aws-region: ${{ secrets.AWS_REGION }}
+      - name: Stop EC2 runner
+        uses: machulav/ec2-github-runner@v2
+        with:
+          mode: stop
+          github-token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }}
+          label: ${{ needs.start-runner.outputs.label }}
+          ec2-instance-id: ${{ needs.start-runner.outputs.ec2-instance-id }}