Linkerd Patterns

Linkerd Patterns

Production patterns for Linkerd service mesh - the lightweight, security-first service mesh for Kubernetes.

Do not use this skill when

• The task is unrelated to linkerd patterns
• You need a different domain or tool outside this scope

Instructions

• Clarify goals, constraints, and required inputs.
• Apply relevant best practices and validate outcomes.
• Provide actionable steps and verification.
• If detailed examples are required, open resources/implementation-playbook.md.

Use this skill when

• Setting up a lightweight service mesh
• Implementing automatic mTLS
• Configuring traffic splits for canary deployments
• Setting up service profiles for per-route metrics
• Implementing retries and timeouts
• Multi-cluster service mesh

Core Concepts

1. Linkerd Architecture

┌─────────────────────────────────────────────┐
│                Control Plane                 │
│  ┌─────────┐ ┌──────────┐ ┌──────────────┐ │
│  │ destiny │ │ identity │ │ proxy-inject │ │
│  └─────────┘ └──────────┘ └──────────────┘ │
└─────────────────────────────────────────────┘
                      │
┌─────────────────────────────────────────────┐
│                 Data Plane                   │
│  ┌─────┐    ┌─────┐    ┌─────┐             │
│  │proxy│────│proxy│────│proxy│             │
│  └─────┘    └─────┘    └─────┘             │
│     │           │           │               │
│  ┌──┴──┐    ┌──┴──┐    ┌──┴──┐            │
│  │ app │    │ app │    │ app │            │
│  └─────┘    └─────┘    └─────┘            │
└─────────────────────────────────────────────┘

2. Key Resources

Templates

Template 1: Mesh Installation

# Install CLI
brew install linkerd

# Alternative: download the official installer, inspect it, then execute it
tmpdir="$(mktemp -d)"
trap 'rm -rf "$tmpdir"' EXIT
curl --proto '=https' --tlsv1.2 -sSfL https://run.linkerd.io/install -o "$tmpdir/linkerd-install.sh"
cat "$tmpdir/linkerd-install.sh"  # review the full installer before executing
sh "$tmpdir/linkerd-install.sh"

# Validate cluster
linkerd check --pre

# Install CRDs
linkerd install --crds | kubectl apply -f -

# Install control plane
linkerd install | kubectl apply -f -

# Verify installation
linkerd check

# Install viz extension (optional)
linkerd viz install | kubectl apply -f -

Template 2: Inject Namespace

# Automatic injection for namespace
apiVersion: v1
kind: Namespace
metadata:
  name: my-app
  annotations:
    linkerd.io/inject: enabled
---
# Or inject specific deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  annotations:
    linkerd.io/inject: enabled
spec:
  template:
    metadata:
      annotations:
        linkerd.io/inject: enabled

Template 3: Service Profile with Retries

apiVersion: linkerd.io/v1alpha2
kind: ServiceProfile
metadata:
  name: my-service.my-namespace.svc.cluster.local
  namespace: my-namespace
spec:
  routes:
    - name: GET /api/users
      condition:
        method: GET
        pathRegex: /api/users
      responseClasses:
        - condition:
            status:
              min: 500
              max: 599
          isFailure: true
      isRetryable: true
    - name: POST /api/users
      condition:
        method: POST
        pathRegex: /api/users
      # POST not retryable by default
      isRetryable: false
    - name: GET /api/users/{id}
      condition:
        method: GET
        pathRegex: /api/users/[^/]+
      timeout: 5s
      isRetryable: true
  retryBudget:
    retryRatio: 0.2
    minRetriesPerSecond: 10
    ttl: 10s

Template 4: Traffic Split (Canary)

apiVersion: split.smi-spec.io/v1alpha1
kind: TrafficSplit
metadata:
  name: my-service-canary
  namespace: my-namespace
spec:
  service: my-service
  backends:
    - service: my-service-stable
      weight: 900m  # 90%
    - service: my-service-canary
      weight: 100m  # 10%

Template 5: Server Authorization Policy

# Define the server
apiVersion: policy.linkerd.io/v1beta1
kind: Server
metadata:
  name: my-service-http
  namespace: my-namespace
spec:
  podSelector:
    matchLabels:
      app: my-service
  port: http
  proxyProtocol: HTTP/1
---
# Allow traffic from specific clients
apiVersion: policy.linkerd.io/v1beta1
kind: ServerAuthorization
metadata:
  name: allow-frontend
  namespace: my-namespace
spec:
  server:
    name: my-service-http
  client:
    meshTLS:
      serviceAccounts:
        - name: frontend
          namespace: my-namespace
---
# Allow unauthenticated traffic (e.g., from ingress)
apiVersion: policy.linkerd.io/v1beta1
kind: ServerAuthorization
metadata:
  name: allow-ingress
  namespace: my-namespace
spec:
  server: