C# Blazor Zero Downtime Deployment — Deploy

Blazor Zero Downtime

C# Blazor Zero Downtime Deployment Rolling Update Blue-Green Canary SignalR Health Check Graceful Shutdown Kubernetes Production

Strategy	Downtime	Rollback	Resource	Complexity
Rolling Update	Zero	Rolling Back	+1 Pod	ต่ำ
Blue-Green	Zero	Instant (สลับ Traffic)	2x Resource	ปานกลาง
Canary	Zero	ส่ง 100% กลับเวอร์ชันเก่า	+10-20% Resource	สูง
Recreate	มี Downtime	Deploy เวอร์ชันเก่า	ปกติ	ต่ำ

Rolling Update Configuration

# === Blazor Server Rolling Update === # apiVersion: apps/v1 # kind: Deployment # metadata: # name: blazor-app # spec: # replicas: 3 # strategy: # type: RollingUpdate # rollingUpdate: # maxSurge: 1 # maxUnavailable: 0 # template: # spec: # terminationGracePeriodSeconds: 60 # containers: # - name: blazor # image: registry.example.com/blazor-app:v2.0 # ports: # - containerPort: 8080 # lifecycle: # preStop: # exec: # command: ["/bin/sh", "-c", "sleep 15"] # readinessProbe: # httpGet: # path: /health/ready # port: 8080 # initialDelaySeconds: 5 # periodSeconds: 5 # failureThreshold: 3 # livenessProbe: # httpGet: # path: /health # port: 8080 # initialDelaySeconds: 15 # periodSeconds: 10 # minReadySeconds: 10 # Program.cs - Graceful Shutdown # var builder = WebApplication.CreateBuilder(args); # builder.Services.AddHealthChecks() # .AddDbContextCheck("database") # .AddCheck("signalr", () => HealthCheckResult.Healthy()); # # var app = builder.Build(); # app.MapHealthChecks("/health"); # app.MapHealthChecks("/health/ready"); # # app.Lifetime.ApplicationStopping.Register(() => { # Log.Information("Shutting down gracefully..."); # Thread.Sleep(10000); // Wait for connections to drain # }); from dataclasses import dataclass @dataclass class RollingConfig: setting: str value: str purpose: str blazor_note: str configs = [ RollingConfig("maxSurge", "1", "เพิ่ม Pod ใหม่ 1 ตัวก่อนลบ Pod เก่า", "Pod ใหม่ต้อง Ready ก่อนรับ SignalR Connections"), RollingConfig("maxUnavailable", "0", "ห้ามลด Pod จนกว่า Pod ใหม่ Ready", "ป้องกัน Connection Drop ระหว่าง Deploy"), RollingConfig("minReadySeconds", "10", "รอ 10 วินาทีหลัง Ready ก่อนดำเนินการต่อ", "ให้ SignalR Hub เริ่มต้นเสร็จสมบูรณ์"), RollingConfig("terminationGracePeriodSeconds", "60", "รอ 60 วินาทีก่อน Force Kill", "ให้เวลา SignalR Connection Drain"), RollingConfig("preStop sleep 15", "sleep 15", "รอ 15 วินาทีก่อน SIGTERM", "ให้ Endpoint ถูกถอดจาก Service ก่อน"), ] print("=== Rolling Update Config ===") for c in configs: print(f" [{c.setting}] = {c.value}") print(f" Purpose: {c.purpose}") print(f" Blazor: {c.blazor_note}")

Blue-Green Deployment

# === Blue-Green Deployment Script ===



# # deploy-blue-green.sh

# #!/bin/bash

# NEW_VERSION=$1

# CURRENT=$(kubectl get svc blazor-app -o jsonpath='{.spec.selector.version}')

#

# if [ "$CURRENT" = "blue" ]; then

#   TARGET="green"

# else

#   TARGET="blue"

# fi

#

# # Deploy new version to target

# kubectl set image deployment/blazor-$TARGET \

#   blazor=registry.example.com/blazor-app:$NEW_VERSION

#

# # Wait for rollout

# kubectl rollout status deployment/blazor-$TARGET --timeout=300s

#

# # Run smoke tests

# ENDPOINT=$(kubectl get svc blazor-$TARGET -o jsonpath='{.status.loadBalancer.ingress[0].ip}')

# curl -f "http://$ENDPOINT/health/ready" || exit 1

#

# # Switch traffic

# kubectl patch svc blazor-app -p "{\"spec\":{\"selector\":{\"version\":\"$TARGET\"}}}"

#

# echo "Switched to $TARGET (v$NEW_VERSION)"



@dataclass

class BlueGreenStep:

    step: int

    action: str

    command: str

    duration: str

    rollback: str



steps = [

    BlueGreenStep(1, "Deploy to Green",

        "kubectl set image deployment/blazor-green",

        "2-5 นาที",

        "ไม่ต้อง (Blue ยังทำงาน)"),

    BlueGreenStep(2, "Wait for Rollout",

        "kubectl rollout status deployment/blazor-green",

        "1-3 นาที",

        "kubectl rollout undo"),

    BlueGreenStep(3, "Smoke Test Green",

        "curl /health/ready + E2E tests",

        "1-5 นาที",

        "ไม่ Switch ถ้า Test Fail"),

    BlueGreenStep(4, "Switch Traffic",

        "kubectl patch svc (change selector)",

        "< 1 วินาที",

        "Switch กลับ Blue ทันที"),

    BlueGreenStep(5, "Monitor Green",

        "Watch error rate, latency, logs",

        "15-30 นาที",

        "Switch กลับ Blue ถ้าผิดปกติ"),

    BlueGreenStep(6, "Cleanup Blue",

        "Scale down Blue (optional)",

        "ทำเมื่อมั่นใจ",

        "เก็บ Blue ไว้ 24 ชม. ก่อนลบ"),

]



print("=== Blue-Green Steps ===")

for s in steps:

    print(f"  Step {s.step}: {s.action} ({s.duration})")

    print(f"    Command: {s.command}")

    print(f"    Rollback: {s.rollback}")

SignalR Connection Handling

# === SignalR Zero Downtime Handling ===



@dataclass

class SignalRStrategy:

    scenario: str

    problem: str

    solution: str

    config: str



signalr_strategies = [

    SignalRStrategy("Pod Termination",

        "SignalR WebSocket Connection หลุดเมื่อ Pod ถูกลบ",

        "preStop hook + Graceful Shutdown รอ Connection Drain",

        "terminationGracePeriodSeconds: 60, preStop sleep 15"),

    SignalRStrategy("Client Reconnection",

        "Client ต้อง Reconnect หลัง Connection หลุด",

        "Blazor Circuit Reconnect UI + Auto-reconnect",

        "Blazor.start({circuit: {reconnectionOptions}})"),

    SignalRStrategy("Session Affinity",

        "SignalR ต้องกลับ Pod เดิม (Sticky Session)",

        "Ingress Cookie Affinity + Redis Backplane",

        "nginx affinity: cookie + AddSignalR().AddRedis()"),

    SignalRStrategy("State Preservation",

        "Circuit State หายเมื่อ Pod ตาย",

        "เก็บ State ใน Redis/Database ไม่ใช่ Memory",

        "IDistributedCache + Redis State Store"),

    SignalRStrategy("Load Balancer Drain",

        "New Connection ยังถูกส่งมา Pod ที่กำลังจะตาย",

        "Readiness Probe Fail → ถอดจาก Service → Drain",

        "readinessProbe + preStop + SIGTERM handler"),

]



print("=== SignalR Strategies ===")

for s in signalr_strategies:

    print(f"\n  [{s.scenario}]")

    print(f"    Problem: {s.problem}")

    print(f"    Solution: {s.solution}")

    print(f"    Config: {s.config}")