linkerd-patterns

Linkerd Patterns

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

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Instructions

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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
curl --proto '=https' --tlsv1.2 -sSfL https://run.linkerd.io/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:
    name: my-service-http
  client:
    unauthenticated: true
    networks:
      - cidr: 10.0.0.0/8

Template 6: HTTPRoute for Advanced Routing

apiVersion: policy.linkerd.io/v1beta2
kind: HTTPRoute
metadata:
  name: my-route
  namespace: my-namespace
spec:
  parentRefs:
    - name: my-service
      kind: Service
      group: core
      port: 8080
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /api/v2
        - headers:
            - name: x-api-version
              value: v2
      backendRefs:
        - name: my-service-v2
          port: 8080
    - matches:
        - path:
            type: PathPrefix
            value: /api
      backendRefs:
        - name: my-service-v1
          port: 8080

Template 7: Multi-cluster Setup

# On each cluster, install with cluster credentials
linkerd multicluster install | kubectl apply -f -
Link clusters

linkerd multicluster link --cluster-name west \
  --api-server-address https://west.example.com:6443 \
  | kubectl apply -f -
Export a service to other clusters

kubectl label svc/my-service mirror.linkerd.io/exported=true
Verify cross-cluster connectivity

linkerd multicluster check
linkerd multicluster gateways

Monitoring Commands

# Live traffic view
linkerd viz top deploy/my-app
Per-route metrics

linkerd viz routes deploy/my-app
Check proxy status

linkerd viz stat deploy -n my-namespace
View service dependencies

linkerd viz edges deploy -n my-namespace
Dashboard

linkerd viz dashboard

Debugging

# Check injection status
linkerd check --proxy -n my-namespace
View proxy logs

kubectl logs deploy/my-app -c linkerd-proxy
Debug identity/TLS

linkerd identity -n my-namespace
Tap traffic (live)

linkerd viz tap deploy/my-app --to deploy/my-backend

Best Practices

Do's

Don'ts

Resources