Add an action to keep our self-hosted runner alive.

This action runs once a week on a cron schedule and does basically
nothing, just waits for the runner to come up and then shuts it down.

.github/workflows/keepalive.yaml

@@ -0,0 +1,74 @@
+name: Weekly register keepalive
+on:
+  schedule:
+    - cron: '0 0 0 * *'
+jobs:
+
+  start_ec2_runner:
+    runs-on: ubuntu-latest
+    env:
+      AWS_KEY_ID: ${{ secrets.AWS_KEY_ID }}
+      AWS_KEY_SECRET: ${{ secrets.AWS_KEY_SECRET }}
+      AWS_INSTANCE_TYPE: ${{ vars.AWS_INSTANCE_TYPE }}
+      AWS_IMAGE_ID: ${{ vars.AWS_IMAGE_ID }}
+      AWS_SECURITY_GROUP: ${{ vars.AWS_SECURITY_GROUP }}
+    outputs:
+      EC2_INSTANCE_ID: ${{ steps.start_runner.outputs.EC2_INSTANCE_ID }}
+    steps:
+      - name: configure_aws
+        run: |
+          set -xe
+          sudo apt update
+          sudo apt install -y awscli jq
+          mkdir ${HOME}/.aws
+          echo "[default]" > ${HOME}/.aws/credentials
+          echo "aws_access_key_id = ${AWS_KEY_ID}" >> ${HOME}/.aws/credentials
+          echo "aws_secret_access_key = ${AWS_KEY_SECRET}" >> ${HOME}/.aws/credentials
+          echo "region = us-east-1" >> ${HOME}/.aws/credentials
+          cat ${HOME}/.aws/credentials
+      - name: start_runner
+        id: start_runner
+        run: |
+          set -xe
+          output=$(aws ec2 run-instances \
+            --instance-type ${AWS_INSTANCE_TYPE} \
+            --image-id ${AWS_IMAGE_ID} \
+            --security-group-ids ${AWS_SECURITY_GROUP} \
+            --count 1)
+          EC2_INSTANCE_ID=$(echo ${output} | jq -r ".Instances[0].InstanceId")
+          echo "EC2_INSTANCE_ID=${EC2_INSTANCE_ID}" >> "$GITHUB_OUTPUT"
+
+  guide_notebooks_regression_ec2:
+    runs-on: [self-hosted, nobrainer-ci-ec2-gpu]
+    needs: start_ec2_runner
+    steps:
+      - name: keepalive_task
+        run: |
+          set -xe
+          ps aux | grep runner
+
+  stop_ec2_runner:
+    if: always()
+    runs-on: ubuntu-latest
+    needs: [start_ec2_runner, guide_notebooks_regression_ec2]
+    env:
+      AWS_KEY_ID: ${{ secrets.AWS_KEY_ID }}
+      AWS_KEY_SECRET: ${{ secrets.AWS_KEY_SECRET }}
+    steps:
+      - name: configure_aws
+        run: |
+          set -xe
+          sudo apt update
+          sudo apt install -y awscli
+          mkdir ${HOME}/.aws
+          echo "[default]" > ${HOME}/.aws/credentials
+          echo "aws_access_key_id = ${AWS_KEY_ID}" >> ${HOME}/.aws/credentials
+          echo "aws_secret_access_key = ${AWS_KEY_SECRET}" >> ${HOME}/.aws/credentials
+          echo "region = us-east-1" >> ${HOME}/.aws/credentials
+          cat ${HOME}/.aws/credentials
+      - name: stop_runner
+        env:
+          EC2_INSTANCE_ID: ${{ needs.start_ec2_runner.outputs.EC2_INSTANCE_ID }}
+        run: |
+          set -xe
+          aws ec2 terminate-instances --instance-ids ${EC2_INSTANCE_ID}