Devcontainer Sandbox Templates#

Devcontainers provide disposable, reproducible development environments that run in a container. You define the tools, extensions, and configuration in a .devcontainer/ directory, and any compatible host – GitHub Codespaces, Gitpod, VS Code with Docker, or the devcontainer CLI – builds and launches the environment from that definition.

For infrastructure validation, devcontainers solve a specific problem: giving every developer and every CI run the exact same set of tools at the exact same versions, without requiring them to install anything on their local machine. A Kubernetes devcontainer includes kind, kubectl, helm, and kustomize at pinned versions. A Terraform devcontainer includes terraform, tflint, checkov, and cloud CLIs. The environment is ready to use the moment it starts.

Trace, Span, and Context#

A trace represents a single request flowing through a distributed system. It is identified by a 128-bit trace ID. A span represents one unit of work within that trace – an HTTP handler, a database query, a message publish. Each span has a name, start time, duration, status, attributes (key-value pairs), and events (timestamped annotations). Spans form a tree: every span except the root has a parent span ID.

EKS Networking and Load Balancing#

EKS networking differs fundamentally from generic Kubernetes networking. Pods get real VPC IP addresses, load balancers are AWS-native resources, and networking decisions have direct cost and IP capacity implications.

VPC CNI: How Pod Networking Works#

The AWS VPC CNI plugin assigns each pod an IP address from your VPC CIDR. Unlike overlay networks (Calico, Flannel), pods are directly routable within the VPC. This means security groups, NACLs, and VPC flow logs all work with pod traffic natively.

Ephemeral Cloud Clusters#

Ephemeral clusters exist for one purpose: validate something, then disappear. They are not staging environments, not shared dev clusters, not long-lived resources that someone forgets to turn off. The operational model is strict – create, validate, destroy – and the entire sequence must be automated so that destruction cannot be forgotten.

The cost of getting this wrong is real. A three-node EKS cluster left running over a weekend costs roughly $15. Left running for a month, $200. Multiply by the number of developers or CI pipelines that create clusters, and forgotten ephemeral infrastructure becomes a significant budget line item. Every template in this article includes auto-destroy mechanisms to prevent this.

From Empty Cluster to Production-Ready#

This is the definitive operational plan for taking a fresh Kubernetes cluster and making it production-ready. Each phase builds on the previous one, with verification steps between phases and rollback notes where applicable. An agent should be able to follow this sequence end-to-end.

Estimated timeline: 5 days for a single operator. Phases 1-2 are blocking prerequisites. Phases 3-6 can partially overlap.

Phase 1 – Foundation (Day 1)#

Everything else depends on a healthy cluster with proper namespacing and storage. Do not proceed until every verification step passes.

GitHub Actions Kubernetes Pipeline#

This guide builds a complete pipeline: push code, build a container image, validate the Helm chart, and deploy to Kubernetes. Each stage gates the next, so broken images never reach your cluster.

Pipeline Overview#

The pipeline has four stages:

1. Build and push the container image to GitHub Container Registry (GHCR).
2. Lint and validate the Helm chart with helm lint and kubeconform.
3. Deploy to dev automatically on pushes to main.
4. Promote to staging and production via manual approval.

Complete Workflow File#

# .github/workflows/deploy.yml
name: Build and Deploy

on:
  push:
    branches: [main]
  workflow_dispatch:
    inputs:
      environment:
        description: "Target environment"
        required: true
        type: choice
        options: [dev, staging, production]

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
    outputs:
      image-tag: ${{ steps.meta.outputs.version }}
    steps:
      - uses: actions/checkout@v4

      - name: Log in to GHCR
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=sha,prefix=
            type=ref,event=branch

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}

  validate:
    runs-on: ubuntu-latest
    needs: build
    steps:
      - uses: actions/checkout@v4

      - name: Install Helm
        uses: azure/setup-helm@v4

      - name: Helm lint
        run: helm lint ./charts/my-app -f charts/my-app/values.yaml

      - name: Install kubeconform
        run: |
          curl -sL https://github.com/yannh/kubeconform/releases/latest/download/kubeconform-linux-amd64.tar.gz \
            | tar xz -C /usr/local/bin

      - name: Validate rendered templates
        run: |
          helm template my-app ./charts/my-app \
            --set image.tag=${{ needs.build.outputs.image-tag }} \
            | kubeconform -strict -summary \
              -kubernetes-version 1.29.0

  deploy-dev:
    runs-on: ubuntu-latest
    needs: [build, validate]
    if: github.ref == 'refs/heads/main'
    environment: dev
    steps:
      - uses: actions/checkout@v4

      - name: Install Helm
        uses: azure/setup-helm@v4

      - name: Set up kubeconfig
        run: |
          mkdir -p ~/.kube
          echo "${{ secrets.KUBECONFIG_DEV }}" | base64 -d > ~/.kube/config
          chmod 600 ~/.kube/config

      - name: Deploy with Helm
        run: |
          helm upgrade --install my-app ./charts/my-app \
            --namespace my-app-dev \
            --create-namespace \
            -f charts/my-app/values-dev.yaml \
            --set image.tag=${{ needs.build.outputs.image-tag }} \
            --wait --timeout 300s

      - name: Verify deployment
        run: kubectl rollout status deployment/my-app -n my-app-dev --timeout=120s

  deploy-staging:
    runs-on: ubuntu-latest
    needs: [build, validate, deploy-dev]
    environment: staging
    steps:
      - uses: actions/checkout@v4

      - name: Install Helm
        uses: azure/setup-helm@v4

      - name: Set up kubeconfig
        run: |
          mkdir -p ~/.kube
          echo "${{ secrets.KUBECONFIG_STAGING }}" | base64 -d > ~/.kube/config
          chmod 600 ~/.kube/config

      - name: Deploy with Helm
        run: |
          helm upgrade --install my-app ./charts/my-app \
            --namespace my-app-staging \
            --create-namespace \
            -f charts/my-app/values-staging.yaml \
            --set image.tag=${{ needs.build.outputs.image-tag }} \
            --wait --timeout 300s

  deploy-production:
    runs-on: ubuntu-latest
    needs: [build, validate, deploy-staging]
    environment: production
    steps:
      - uses: actions/checkout@v4

      - name: Install Helm
        uses: azure/setup-helm@v4

      - name: Set up kubeconfig
        run: |
          mkdir -p ~/.kube
          echo "${{ secrets.KUBECONFIG_PROD }}" | base64 -d > ~/.kube/config
          chmod 600 ~/.kube/config

      - name: Deploy with Helm
        run: |
          helm upgrade --install my-app ./charts/my-app \
            --namespace my-app-prod \
            --create-namespace \
            -f charts/my-app/values-production.yaml \
            --set image.tag=${{ needs.build.outputs.image-tag }} \
            --wait --timeout 300s

Key Design Decisions#

Image Tagging with Git SHA#

The docker/metadata-action generates tags from the git SHA. This creates immutable, traceable image tags – you can always identify exactly which commit produced a given deployment.

GPU and ML Workloads on Kubernetes#

Running GPU workloads on Kubernetes requires hardware-aware scheduling that the default scheduler does not provide out of the box. GPUs are expensive – an NVIDIA A100 node costs $3-12/hour on cloud providers – so efficient utilization matters far more than with CPU workloads. This article covers the full stack from device plugin installation through GPU sharing and monitoring.

The NVIDIA Device Plugin#

Kubernetes has no native understanding of GPUs. The NVIDIA device plugin bridges that gap by exposing GPUs as a schedulable resource (nvidia.com/gpu). Without it, the scheduler has no idea which nodes have GPUs or how many are available.

Loki Architecture#

Loki is a log aggregation system designed by Grafana Labs. Unlike Elasticsearch, Loki does not index log content. It indexes only metadata labels, then stores compressed log chunks in object storage. This makes it cheaper to operate and simpler to scale, at the cost of slower full-text search across massive datasets.

The core components are:

• Distributor: Receives incoming log streams from agents, validates labels, and forwards to ingesters via consistent hashing.
• Ingester: Buffers log data in memory, builds compressed chunks, and flushes them to long-term storage (S3, GCS, filesystem).
• Querier: Executes LogQL queries by fetching chunk references from the index and reading chunk data from storage.
• Compactor: Runs periodic compaction on the index (especially for boltdb-shipper) and handles retention enforcement by deleting old data.
• Query Frontend (optional): Splits large queries into smaller ones, caches results, and distributes work across queriers.

Deployment Modes#

Loki supports three deployment modes, each suited to different scales.

Grafana Mimir for Long-Term Prometheus Storage#

Prometheus stores metrics on local disk with a practical retention limit of weeks to a few months. Beyond that, you need a long-term storage solution. Grafana Mimir is a horizontally scalable, multi-tenant time series database designed for exactly this purpose. It is API-compatible with Prometheus – Grafana queries Mimir using the same PromQL, and Prometheus pushes data to Mimir via remote_write.

Mimir is the successor to Cortex. Grafana Labs forked Cortex, rewrote significant portions for performance, and released Mimir under the AGPLv3 license. If you see references to Cortex architecture, the concepts map directly to Mimir with improvements.

HashiCorp Vault on Kubernetes#

Vault centralizes secret management with dynamic credentials, encryption as a service, and fine-grained access control. On Kubernetes, workloads authenticate using service accounts and pull secrets without hardcoding anything.

Installation with Helm#

helm repo add hashicorp https://helm.releases.hashicorp.com
helm repo update

Dev Mode (Single Pod, In-Memory)#

Automatically initialized and unsealed, stores everything in memory, loses all data on restart. Root token is root. Never use this in production.

helm upgrade --install vault hashicorp/vault \
  --namespace vault --create-namespace \
  --set server.dev.enabled=true \
  --set injector.enabled=true

Production Mode (HA with Integrated Raft Storage)#

Run Vault in HA mode with Raft consensus – a 3-node StatefulSet with persistent storage.