GitHub ARC en GKE

🚀 Descripción General

Este documento explica cómo implementar Actions Runner Controller (ARC) en Google Kubernetes Engine (GKE), configurar runner scale sets y habilitar Docker-in-Docker (dind) para ejecutar flujos de GitHub Actions dentro de Kubernetes.

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🧩 Arquitectura General

flowchart TD
    A[GitHub Actions] --> B[ARC - Runner Scale Set]
    B --> C[GKE Cluster]
    C --> D[ARC Controller]
    C --> E[Runner Pods]
    E --> F[Docker-in-Docker Builds]
    F --> G[GHCR Registry]

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1️⃣ Crear el clúster de GKE

export PROJECT_ID="PROYECTO_GOOGLE"
export REGION="us-central1"
export ZONE="${REGION}-a"
export CLUSTER_NAME="arc-gke-standard"
export MACHINE_TYPE="e2-standard-4"
export NODE_COUNT="1"

gcloud config set project $PROJECT_ID

gcloud container clusters create $CLUSTER_NAME \
  --zone $ZONE \
  --num-nodes $NODE_COUNT \
  --machine-type $MACHINE_TYPE \
  --image-type UBUNTU_CONTAINERD \
  --disk-size 100 \
  --metadata disable-legacy-endpoints=true \
  --workload-pool="${PROJECT_ID}.svc.id.goog" \
  --enable-network-policy \
  --enable-autoupgrade \
  --enable-autorepair \
  --no-enable-shielded-nodes

gcloud container clusters get-credentials $CLUSTER_NAME --zone $ZONE
kubectl get nodes -o wide

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2️⃣ Desplegar ARC Controller

export ARC_NAMESPACE="arc-systems"

helm install arc \
  --namespace "${ARC_NAMESPACE}" \
  --create-namespace \
  oci://ghcr.io/actions/actions-runner-controller-charts/gha-runner-scale-set-controller


kubectl get pods -n ${ARC_NAMESPACE}

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3️⃣ Crear Token de GitHub y configurar runners

export GITHUB_PAT="PON_AQUI_TU_TOKEN"
export RUNNERS_NAMESPACE="arc-runners"
export INSTALLATION_NAME="arc-runner-set"
export GITHUB_CONFIG_URL="https://github.com/TU_ORG"

helm install "${INSTALLATION_NAME}" \
  --namespace "${RUNNERS_NAMESPACE}" \
  --create-namespace \
  --set githubConfigUrl="${GITHUB_CONFIG_URL}" \
  --set githubConfigSecret.github_token="${GITHUB_PAT}" \
  --set containerMode.type="dind" \
  --set dind.privileged=true \
  oci://ghcr.io/actions/actions-runner-controller-charts/gha-runner-scale-set


kubectl get pods -n ${RUNNERS_NAMESPACE}

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🏗️ Diagrama del flujo CI/CD con ARC

sequenceDiagram
    participant GH as GitHub
    participant ARC as ARC Controller
    participant RS as Runner Scale Set
    participant POD as Runner Pod (DinD)
    participant REG as GHCR Registry

    GH->>ARC: Trigger workflow
    ARC->>RS: Solicita Runner
    RS->>POD: Crea pod runner
    POD->>POD: Ejecuta build Docker-in-Docker
    POD->>REG: Push de imagen
    POD->>GH: Reporta estado del job

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4️⃣ Workflow de prueba: .github/workflows/01-test-arc.yml

name: 01 - Test ARC

on:
  workflow_dispatch:

jobs:
  test:
    runs-on: arc-runner-set
    steps:
      - uses: actions/checkout@v4
      - name: Info del runner
        run: |
          echo "ARC está funcionando en GKE"
          uname -a
          hostname

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5️⃣ Dockerfile de ejemplo

FROM alpine:3.20
RUN apk add --no-cache curl
CMD ["sh", "-c", "echo 'Hola desde ARC con dind en GKE'"]

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6️⃣ Workflow de build Docker-in-Docker

name: 02 - Build & Push Docker-in-Docker

on:
  workflow_dispatch:

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository_owner }}/arc-lab-demo

jobs:
  build:
    runs-on: arc-runner-set

    permissions:
      contents: read
      packages: write

    steps:
      - uses: actions/checkout@v4

      - name: Login en GHCR
        run: |
          echo "${{ github.token }}" | docker login ghcr.io             -u ${{ github.actor }} --password-stdin

      - name: Build de la imagen
        run: |
          IMAGE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}"
          docker build -t "$IMAGE" .

      - name: Push de la imagen
        run: |
          IMAGE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}"
          docker push "$IMAGE"

      - name: Test local del contenedor
        run: |
          IMAGE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}"
          docker run --rm "$IMAGE"

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✔️ Resultado Final

Con este setup:

• GKE ejecuta runners de GitHub Actions
• ARC administra los runners dinámicamente
• Se soporta Docker-in-Docker totalmente funcional
• Puedes construir y publicar imágenes en GHCR desde Kubernetes

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