Golang PaaS平台站点可靠性工程师（SRE）岗位探讨

这是一个非常典型的现代PaaS平台SRE岗位描述，结合了平台工程和传统SRE职责。从技术栈来看，这个团队深度依赖Go语言构建自动化工具和平台服务。以下是一些关键点的技术分析和示例：

核心Go技术栈应用

1. Kubernetes Operator开发

团队需要构建软件来管理平台基础设施，这通常涉及编写Kubernetes Operator：

package main

import (
    "context"
    "fmt"
    "time"

    appsv1 "k8s.io/api/apps/v1"
    corev1 "k8s.io/api/core/v1"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/apimachinery/pkg/runtime"
    ctrl "sigs.k8s.io/controller-runtime"
    "sigs.k8s.io/controller-runtime/pkg/client"
    "sigs.k8s.io/controller-runtime/pkg/log"
)

// PlatformAppReconciler 管理平台应用的自定义控制器
type PlatformAppReconciler struct {
    client.Client
    Scheme *runtime.Scheme
}

func (r *PlatformAppReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
    logger := log.FromContext(ctx)
    
    // 获取自定义资源
    var platformApp PlatformApp
    if err := r.Get(ctx, req.NamespacedName, &platformApp); err != nil {
        return ctrl.Result{}, client.IgnoreNotFound(err)
    }
    
    // 检查并创建对应的Deployment
    var deployment appsv1.Deployment
    err := r.Get(ctx, req.NamespacedName, &deployment)
    if err != nil {
        // 创建新的Deployment
        deployment = *r.constructDeployment(&platformApp)
        if err := r.Create(ctx, &deployment); err != nil {
            logger.Error(err, "无法创建Deployment")
            return ctrl.Result{}, err
        }
        logger.Info("Deployment创建成功")
    }
    
    // 确保Service存在
    var service corev1.Service
    serviceKey := client.ObjectKey{Name: platformApp.Name + "-svc", Namespace: req.Namespace}
    if err := r.Get(ctx, serviceKey, &service); err != nil {
        service = *r.constructService(&platformApp)
        if err := r.Create(ctx, &service); err != nil {
            logger.Error(err, "无法创建Service")
            return ctrl.Result{}, err
        }
    }
    
    return ctrl.Result{RequeueAfter: 5 * time.Minute}, nil
}

2. 监控和指标收集

针对症状开发监控规则，使用Prometheus客户端库：

package monitoring

import (
    "net/http"
    "time"

    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promauto"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)

var (
    platformRequestsTotal = promauto.NewCounterVec(
        prometheus.CounterOpts{
            Name: "platform_requests_total",
            Help: "平台API请求总数",
        },
        []string{"endpoint", "method", "status"},
    )
    
    requestDuration = promauto.NewHistogramVec(
        prometheus.HistogramOpts{
            Name:    "http_request_duration_seconds",
            Help:    "HTTP请求耗时分布",
            Buckets: prometheus.DefBuckets,
        },
        []string{"endpoint", "method"},
    )
    
    kubernetesResourceUsage = promauto.NewGaugeVec(
        prometheus.GaugeOpts{
            Name: "k8s_resource_usage_percent",
            Help: "Kubernetes资源使用率",
        },
        []string{"namespace", "resource_type", "node"},
    )
)

// MonitorMiddleware HTTP监控中间件
func MonitorMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        start := time.Now()
        
        // 包装ResponseWriter以获取状态码
        rw := &responseWriter{ResponseWriter: w, statusCode: http.StatusOK}
        
        next.ServeHTTP(rw, r)
        
        duration := time.Since(start).Seconds()
        endpoint := r.URL.Path
        method := r.Method
        status := http.StatusText(rw.statusCode)
        
        // 记录指标
        platformRequestsTotal.WithLabelValues(endpoint, method, status).Inc()
        requestDuration.WithLabelValues(endpoint, method).Observe(duration)
    })
}

// 启动指标服务器
func StartMetricsServer(addr string) {
    http.Handle("/metrics", promhttp.Handler())
    go func() {
        http.ListenAndServe(addr, nil)
    }()
}

3. 自动化部署和GitOps工具

改进部署流程的自动化工具：

package deployment

import (
    "context"
    "encoding/json"
    "fmt"
    "io"
    "net/http"
    "time"

    "github.com/go-git/go-git/v5"
    "github.com/go-git/go-git/v5/plumbing"
    "github.com/go-git/go-git/v5/plumbing/object"
    "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
    "k8s.io/apimachinery/pkg/util/yaml"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/rest"
)

// GitOpsDeployer 处理GitOps风格的部署
type GitOpsDeployer struct {
    RepoURL    string
    LocalPath  string
    Branch     string
    K8sClient  *kubernetes.Clientset
}

// SyncFromGit 从Git仓库同步配置到Kubernetes
func (d *GitOpsDeployer) SyncFromGit(ctx context.Context) error {
    // 克隆或拉取最新代码
    repo, err := d.ensureRepo()
    if err != nil {
        return fmt.Errorf("无法获取仓库: %v", err)
    }
    
    // 切换到指定分支
    worktree, err := repo.Worktree()
    if err != nil {
        return err
    }
    
    err = worktree.Pull(&git.PullOptions{
        RemoteName: "origin",
        ReferenceName: plumbing.ReferenceName(fmt.Sprintf("refs/heads/%s", d.Branch)),
    })
    
    // 解析和应用Kubernetes清单
    return d.applyManifests(ctx)
}

// applyManifests 应用Kubernetes配置
func (d *GitOpsDeployer) applyManifests(ctx context.Context) error {
    // 遍历目录，查找YAML文件
    manifests, err := findYAMLFiles(d.LocalPath)
    if err != nil {
        return err
    }
    
    for _, manifest := range manifests {
        var obj unstructured.Unstructured
        data, err := io.ReadFile(manifest)
        if err != nil {
            continue
        }
        
        // 解码YAML
        jsonData, err := yaml.ToJSON(data)
        if err != nil {
            continue
        }
        
        if err := json.Unmarshal(jsonData, &obj); err != nil {
            continue
        }
        
        // 根据资源类型应用配置
        if err := d.applyObject(ctx, &obj); err != nil {
            return fmt.Errorf("应用 %s 失败: %v", manifest, err)
        }
    }
    
    return nil
}

// HealthChecker 服务健康检查
type HealthChecker struct {
    Client *http.Client
}

// CheckServiceHealth 执行综合健康检查
func (h *HealthChecker) CheckServiceHealth(endpoints []string) map[string]bool {
    results := make(map[string]bool)
    
    for _, endpoint := range endpoints {
        ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
        defer cancel()
        
        req, err := http.NewRequestWithContext(ctx, "GET", endpoint, nil)
        if err != nil {
            results[endpoint] = false
            continue
        }
        
        resp, err := h.Client.Do(req)
        if err != nil {
            results[endpoint] = false
            continue
        }
        defer resp.Body.Close()
        
        results[endpoint] = resp.StatusCode >= 200 && resp.StatusCode < 300
    }
    
    return results
}

4. 事件处理和告警自动化

事件响应自动化工具：

package incident

import (
    "context"
    "encoding/json"
    "fmt"
    "log"
    "time"

    "cloud.google.com/go/pubsub"
    "github.com/slack-go/slack"
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/trace"
)

// IncidentManager 管理事件生命周期
type IncidentManager struct {
    PubSubClient *pubsub.Client
    SlackClient  *slack.Client
    Tracer       trace.Tracer
}

// HandleAlert 处理传入的告警
func (im *IncidentManager) HandleAlert(ctx context.Context, alertData []byte) error {
    ctx, span := im.Tracer.Start(ctx, "HandleAlert")
    defer span.End()
    
    var alert Alert
    if err := json.Unmarshal(alertData, &alert); err != nil {
        span.RecordError(err)
        return err
    }
    
    span.SetAttributes(
        attribute.String("alert.severity", alert.Severity),
        attribute.String("alert.service", alert.Service),
    )
    
    // 根据严重程度采取不同行动
    switch alert.Severity {
    case "critical":
        return im.handleCriticalAlert(ctx, alert)
    case "warning":
        return im.handleWarningAlert(ctx, alert)
    default:
        return im.handleInfoAlert(ctx, alert)
    }
}

// handleCriticalAlert 处理严重告警
func (im *IncidentManager) handleCriticalAlert(ctx context.Context, alert Alert) error {
    // 1. 发送Slack通知
    _, _, err := im.SlackClient.PostMessage(
        "incidents-channel",
        slack.MsgOptionText(fmt.Sprintf("🚨 严重告警: %s - %s", alert.Service, alert.Description), false),
        slack.MsgOptionAttachments(slack.Attachment{
            Color: "danger",
            Fields: []slack.AttachmentField{
                {Title: "服务", Value: alert.Service},
                {Title: "严重程度", Value: alert.Severity},
                {Title: "时间", Value: time.Now().Format(time.RFC3339)},
            },
        }),
    )
    
    // 2. 创建事件记录
    incident := Incident{
        ID:          generateIncidentID(),
        Service:     alert.Service,
        Severity:    alert.Severity,
        Description: alert.Description,
        CreatedAt:   time.Now(),
        Status:      "investigating",
    }
    
    // 3. 发布到Pub/Sub进行进一步处理
    topic := im.PubSubClient.Topic("incidents")
    data, _ := json.Marshal(incident)
    result := topic.Publish(ctx, &pubsub.Message{Data: data})
    
    if _, err := result.Get(ctx); err != nil {
        log.Printf("发布事件失败: %v", err)
    }
    
    // 4. 触发自动化修复流程
    go im.attemptAutoRemediation(ctx, incident)
    
    return nil
}

// SLO计算和报告
type SLOTracker struct {
    WindowSize time.Duration
}

// CalculateAvailability 计算服务可用性
func (st *SLOTracker) CalculateAvailability(service string, window time.Duration) float64 {
    // 查询时间窗口内的错误率和总请求数
    totalRequests := queryTotalRequests(service, window)
    failedRequests := queryFailedRequests(service, window)
    
    if totalRequests == 0 {
        return 100.0
    }
    
    availability := (float64(totalRequests-failedRequests) / float64(totalRequests)) * 100
    return availability
}

// GenerateSLOReport 生成SLO报告
func (st *SLOTracker) GenerateSLOReport(services []string) map[string]SLOResult {
    results := make(map[string]SLOResult)
    
    for _, service := range services {
        // 计算不同时间窗口的可用性
        daily := st.CalculateAvailability(service, 24*time.Hour)
        weekly := st.CalculateAvailability(service, 7*24*time.Hour)
        monthly := st.CalculateAvailability(service, 30*24*time.Hour)
        
        results[service] = SLOResult{
            Service:      service,
            Daily:        daily,
            Weekly:       weekly,
            Monthly:      monthly,
            MeetsSLO:     monthly >= 99.9, // 假设SLO是99.9%
            ErrorBudget:  calculateErrorBudget(monthly, 99.9),
        }
    }
    
    return results
}

这个岗位要求SRE不仅能够运维平台，更需要用Go语言构建自动化工具和平台服务。代码示例展示了如何在实际工作中应用Go语言解决PaaS平台的可靠性、自动化和监控需求。团队强调"以开发为核心"，这意味着大部分运维工作都需要通过代码和自动化来实现，而不是手动操作。