probe: runner label availability + vtop peak CPU-request measurement

Temporary investigation branch. Not for merge.

Author: fasterrt

.github/workflows/a1_labels.yml

@@ -0,0 +1,27 @@
+name: a1_labels
+on:
+  push:
+    branches:
+      - "a1-probe-*"
+
+jobs:
+  probe:
+    name: probe (${{ matrix.label }})
+    continue-on-error: true
+    timeout-minutes: 6
+    strategy:
+      fail-fast: false
+      matrix:
+        label:
+          - oracle-vm-8cpu-32gb-x86-64
+          - gh-hosted-runners-16cores-1-24.04
+          - ubuntu-latest-4-cores
+          - ubuntu-latest-8-cores
+    runs-on: ${{ matrix.label }}
+    steps:
+      - name: capacity
+        run: |
+          echo "LABEL=${{ matrix.label }}"
+          echo "CPUS=$(nproc)"
+          free -m | sed -n '2p'
+          df -h / | tail -1

.github/workflows/a1_vtop_capacity.yml

@@ -0,0 +1,96 @@
+name: a1_vtop_capacity
+on:
+  push:
+    branches:
+      - "a1-probe-*"
+
+jobs:
+  build:
+    name: VTop Capacity Probe (${{ matrix.label }})
+    continue-on-error: true
+    strategy:
+      fail-fast: false
+      matrix:
+        label:
+          - ubuntu-latest-xl
+    runs-on: ${{ matrix.label }}
+
+    steps:
+      - name: Check out code
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: 'false'
+
+      - name: Host capacity
+        run: |
+          echo "LABEL=${{ matrix.label }}"
+          echo "CPUS=$(nproc)"
+          free -m | sed -n '2p'
+
+      - name: Set up Go
+        uses: actions/setup-go@d35c59abb061a4a6fb18e82ac0862c26744d6ab5 # v5.5.0
+        with:
+          go-version-file: go.mod
+
+      - name: Tune the OS
+        uses: ./.github/actions/tune-os
+
+      - name: Setup MySQL
+        uses: ./.github/actions/setup-mysql
+        with:
+          flavor: mysql-8.4
+
+      - name: Get dependencies
+        run: |
+          sudo apt-get install -y make
+          go mod download
+
+      - name: Build vitess
+        run: |
+          make build
+
+      - name: Install kubectl & kind
+        run: |
+          make install_kubectl_kind
+
+      - name: Start CPU-request sampler
+        run: |
+          cat > /tmp/sampler.sh <<'EOS'
+          #!/usr/bin/env bash
+          # Samples node-level scheduled CPU/memory *requests* every 10s.
+          # Kubernetes schedules on requests, so peak requests == the real node sizing requirement.
+          echo "ts,cpu_req_m,mem_req_mi,pods_total,pods_pending" > /tmp/cap.csv
+          while true; do
+            desc=$(kubectl describe node 2>/dev/null | awk '/^Allocated resources:/{f=1} f&&/^  cpu /{print $2; exit}')
+            memd=$(kubectl describe node 2>/dev/null | awk '/^Allocated resources:/{f=1} f&&/^  memory /{print $2; exit}')
+            tot=$(kubectl get pods -A --no-headers 2>/dev/null | wc -l | tr -d ' ')
+            pend=$(kubectl get pods -A --no-headers 2>/dev/null | grep -c Pending)
+            [ -n "$desc" ] && echo "$(date -u +%H:%M:%S),${desc%m},${memd%Mi},$tot,$pend" >> /tmp/cap.csv
+            sleep 10
+          done
+          EOS
+          chmod +x /tmp/sampler.sh
+          nohup /tmp/sampler.sh > /tmp/sampler.log 2>&1 &
+          echo "sampler pid $!"
+
+      - name: vtop_example
+        timeout-minutes: 60
+        run: |
+          source build.env
+          go run test.go -docker=false -skip-build -print-log -follow -timeout=60m vtop_example
+
+      - name: Peak scheduled-request report
+        if: always()
+        run: |
+          set +e
+          echo "::group::raw samples"
+          cat /tmp/cap.csv
+          echo "::endgroup::"
+          echo "===== A1 CAPACITY RESULT ====="
+          echo "HOST_CPUS=$(nproc)"
+          awk -F, 'NR>1 && $2+0>m {m=$2+0} END {printf "PEAK_CPU_REQUEST_MILLICORES=%d\n", m}' /tmp/cap.csv
+          awk -F, 'NR>1 && $3+0>m {m=$3+0} END {printf "PEAK_MEM_REQUEST_MI=%d\n", m}' /tmp/cap.csv
+          awk -F, 'NR>1 && $4+0>m {m=$4+0} END {printf "PEAK_POD_COUNT=%d\n", m}' /tmp/cap.csv
+          awk -F, 'NR>1 {s+=$5} END {printf "PENDING_SAMPLE_TOTAL=%d\n", s}' /tmp/cap.csv
+          echo "SAMPLES=$(( $(wc -l < /tmp/cap.csv) - 1 ))"
+          echo "=============================="