|
| 1 | +// SPDX-FileCopyrightText: 2025 The Kepler Authors |
| 2 | +// SPDX-License-Identifier: Apache-2.0 |
| 3 | + |
| 4 | +package pod |
| 5 | + |
| 6 | +import ( |
| 7 | + "context" |
| 8 | + "crypto/tls" |
| 9 | + "encoding/json" |
| 10 | + "fmt" |
| 11 | + "log/slog" |
| 12 | + "net/http" |
| 13 | + "os" |
| 14 | + "sync" |
| 15 | + "time" |
| 16 | + |
| 17 | + corev1 "k8s.io/api/core/v1" |
| 18 | +) |
| 19 | + |
| 20 | +const ( |
| 21 | + defaultKubeletPort = 10250 |
| 22 | + defaultPollInterval = 15 * time.Second |
| 23 | + defaultRequestTimeout = 10 * time.Second |
| 24 | + serviceAccountTokenPath = "/var/run/secrets/kubernetes.io/serviceaccount/token" |
| 25 | +) |
| 26 | + |
| 27 | +// getDefaultKubeletHost returns the kubelet host from NODE_IP env var, |
| 28 | +// falling back to "localhost" if not set. The NODE_IP should be set via |
| 29 | +// downward API (status.hostIP) in the pod spec. |
| 30 | +func getDefaultKubeletHost() string { |
| 31 | + if nodeIP := os.Getenv("NODE_IP"); nodeIP != "" { |
| 32 | + return nodeIP |
| 33 | + } |
| 34 | + return "localhost" |
| 35 | +} |
| 36 | + |
| 37 | +type kubeletPodInformer struct { |
| 38 | + logger *slog.Logger |
| 39 | + nodeName string |
| 40 | + kubeletHost string |
| 41 | + kubeletPort int |
| 42 | + pollInterval time.Duration |
| 43 | + |
| 44 | + httpClient *http.Client |
| 45 | + token string |
| 46 | + |
| 47 | + mu sync.RWMutex |
| 48 | + cache map[string]*ContainerInfo // containerID -> ContainerInfo |
| 49 | +} |
| 50 | + |
| 51 | +// NewKubeletInformer creates a new kubelet-based pod informer that polls |
| 52 | +// the local kubelet /pods endpoint instead of watching the API server. |
| 53 | +func NewKubeletInformer(opts ...OptFn) *kubeletPodInformer { |
| 54 | + opt := DefaultOpts() |
| 55 | + for _, fn := range opts { |
| 56 | + fn(&opt) |
| 57 | + } |
| 58 | + |
| 59 | + host := opt.kubeletHost |
| 60 | + if host == "" { |
| 61 | + host = getDefaultKubeletHost() |
| 62 | + } |
| 63 | + port := opt.kubeletPort |
| 64 | + if port == 0 { |
| 65 | + port = defaultKubeletPort |
| 66 | + } |
| 67 | + interval := opt.pollInterval |
| 68 | + if interval == 0 { |
| 69 | + interval = defaultPollInterval |
| 70 | + } |
| 71 | + |
| 72 | + return &kubeletPodInformer{ |
| 73 | + logger: opt.logger.With("service", "kubeletPodInformer"), |
| 74 | + nodeName: opt.nodeName, |
| 75 | + kubeletHost: host, |
| 76 | + kubeletPort: port, |
| 77 | + pollInterval: interval, |
| 78 | + cache: make(map[string]*ContainerInfo), |
| 79 | + } |
| 80 | +} |
| 81 | + |
| 82 | +func (i *kubeletPodInformer) Name() string { |
| 83 | + return "kubeletPodInformer" |
| 84 | +} |
| 85 | + |
| 86 | +func (i *kubeletPodInformer) Init() error { |
| 87 | + if i.nodeName == "" { |
| 88 | + return fmt.Errorf("nodeName not set") |
| 89 | + } |
| 90 | + |
| 91 | + // Read ServiceAccount token |
| 92 | + tokenBytes, err := os.ReadFile(serviceAccountTokenPath) |
| 93 | + if err != nil { |
| 94 | + return fmt.Errorf("failed to read SA token: %w", err) |
| 95 | + } |
| 96 | + i.token = string(tokenBytes) |
| 97 | + |
| 98 | + // Setup HTTP client with TLS (kubelet uses self-signed cert) |
| 99 | + i.httpClient = &http.Client{ |
| 100 | + Timeout: defaultRequestTimeout, |
| 101 | + Transport: &http.Transport{ |
| 102 | + TLSClientConfig: &tls.Config{ |
| 103 | + InsecureSkipVerify: true, // kubelet uses self-signed cert |
| 104 | + }, |
| 105 | + }, |
| 106 | + } |
| 107 | + |
| 108 | + // Do initial fetch |
| 109 | + if err := i.refresh(); err != nil { |
| 110 | + return fmt.Errorf("initial kubelet fetch failed: %w", err) |
| 111 | + } |
| 112 | + |
| 113 | + i.logger.Info("kubelet pod informer initialized", |
| 114 | + "nodeName", i.nodeName, |
| 115 | + "kubeletHost", i.kubeletHost, |
| 116 | + "kubeletPort", i.kubeletPort, |
| 117 | + "pollInterval", i.pollInterval) |
| 118 | + |
| 119 | + return nil |
| 120 | +} |
| 121 | + |
| 122 | +func (i *kubeletPodInformer) Run(ctx context.Context) error { |
| 123 | + i.logger.Info("starting kubelet pod informer") |
| 124 | + ticker := time.NewTicker(i.pollInterval) |
| 125 | + defer ticker.Stop() |
| 126 | + |
| 127 | + for { |
| 128 | + select { |
| 129 | + case <-ctx.Done(): |
| 130 | + i.logger.Info("kubelet pod informer stopped") |
| 131 | + return nil |
| 132 | + case <-ticker.C: |
| 133 | + if err := i.refresh(); err != nil { |
| 134 | + i.logger.Warn("failed to refresh pods from kubelet", "error", err) |
| 135 | + } |
| 136 | + } |
| 137 | + } |
| 138 | +} |
| 139 | + |
| 140 | +func (i *kubeletPodInformer) refresh() error { |
| 141 | + url := fmt.Sprintf("https://%s:%d/pods", i.kubeletHost, i.kubeletPort) |
| 142 | + |
| 143 | + req, err := http.NewRequest(http.MethodGet, url, nil) |
| 144 | + if err != nil { |
| 145 | + return err |
| 146 | + } |
| 147 | + req.Header.Set("Authorization", "Bearer "+i.token) |
| 148 | + |
| 149 | + resp, err := i.httpClient.Do(req) |
| 150 | + if err != nil { |
| 151 | + return err |
| 152 | + } |
| 153 | + defer resp.Body.Close() |
| 154 | + |
| 155 | + if resp.StatusCode != http.StatusOK { |
| 156 | + return fmt.Errorf("kubelet returned status %d", resp.StatusCode) |
| 157 | + } |
| 158 | + |
| 159 | + var podList corev1.PodList |
| 160 | + if err := json.NewDecoder(resp.Body).Decode(&podList); err != nil { |
| 161 | + return fmt.Errorf("failed to decode pod list: %w", err) |
| 162 | + } |
| 163 | + |
| 164 | + // Build container ID -> pod info cache |
| 165 | + newCache := make(map[string]*ContainerInfo) |
| 166 | + for _, pod := range podList.Items { |
| 167 | + i.addContainersToCache(newCache, &pod, pod.Status.ContainerStatuses) |
| 168 | + i.addContainersToCache(newCache, &pod, pod.Status.InitContainerStatuses) |
| 169 | + i.addContainersToCache(newCache, &pod, pod.Status.EphemeralContainerStatuses) |
| 170 | + } |
| 171 | + |
| 172 | + i.mu.Lock() |
| 173 | + i.cache = newCache |
| 174 | + i.mu.Unlock() |
| 175 | + |
| 176 | + i.logger.Debug("refreshed pod cache from kubelet", |
| 177 | + "podCount", len(podList.Items), |
| 178 | + "containerCount", len(newCache)) |
| 179 | + return nil |
| 180 | +} |
| 181 | + |
| 182 | +func (i *kubeletPodInformer) addContainersToCache(cache map[string]*ContainerInfo, pod *corev1.Pod, statuses []corev1.ContainerStatus) { |
| 183 | + for _, status := range statuses { |
| 184 | + if status.ContainerID == "" { |
| 185 | + continue |
| 186 | + } |
| 187 | + containerID := extractContainerID(status.ContainerID) |
| 188 | + cache[containerID] = &ContainerInfo{ |
| 189 | + PodID: string(pod.UID), |
| 190 | + PodName: pod.Name, |
| 191 | + Namespace: pod.Namespace, |
| 192 | + ContainerName: status.Name, |
| 193 | + } |
| 194 | + } |
| 195 | +} |
| 196 | + |
| 197 | +// LookupByContainerID retrieves pod details and container name given a containerID. |
| 198 | +// If the containerID is not found in cache, it triggers an immediate refresh. |
| 199 | +func (i *kubeletPodInformer) LookupByContainerID(containerID string) (*ContainerInfo, bool, error) { |
| 200 | + i.mu.RLock() |
| 201 | + info, found := i.cache[containerID] |
| 202 | + i.mu.RUnlock() |
| 203 | + |
| 204 | + if found { |
| 205 | + return info, true, nil |
| 206 | + } |
| 207 | + |
| 208 | + // Trigger immediate refresh for unknown container |
| 209 | + if err := i.refresh(); err != nil { |
| 210 | + i.logger.Warn("on-demand refresh failed", "error", err) |
| 211 | + } |
| 212 | + |
| 213 | + i.mu.RLock() |
| 214 | + info, found = i.cache[containerID] |
| 215 | + i.mu.RUnlock() |
| 216 | + |
| 217 | + if !found { |
| 218 | + return nil, false, nil |
| 219 | + } |
| 220 | + return info, true, nil |
| 221 | +} |
0 commit comments