157 lines
3.5 KiB
Go
157 lines
3.5 KiB
Go
package process
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import (
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"context"
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"fmt"
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"io"
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"net"
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"net/http"
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"strings"
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"sync"
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"time"
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coreerr "dappco.re/go/core/log"
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)
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// HealthCheck is a function that returns nil if healthy.
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type HealthCheck func() error
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// HealthServer provides HTTP /health and /ready endpoints for process monitoring.
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type HealthServer struct {
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addr string
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server *http.Server
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listener net.Listener
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mu sync.Mutex
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ready bool
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checks []HealthCheck
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}
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// NewHealthServer creates a health check server on the given address.
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func NewHealthServer(addr string) *HealthServer {
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return &HealthServer{
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addr: addr,
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ready: true,
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}
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}
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// AddCheck registers a health check function.
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func (h *HealthServer) AddCheck(check HealthCheck) {
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h.mu.Lock()
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h.checks = append(h.checks, check)
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h.mu.Unlock()
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}
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// SetReady sets the readiness status.
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func (h *HealthServer) SetReady(ready bool) {
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h.mu.Lock()
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h.ready = ready
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h.mu.Unlock()
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}
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// Start begins serving health check endpoints.
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func (h *HealthServer) Start() error {
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mux := http.NewServeMux()
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mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
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h.mu.Lock()
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checks := h.checks
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h.mu.Unlock()
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for _, check := range checks {
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if err := check(); err != nil {
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w.WriteHeader(http.StatusServiceUnavailable)
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_, _ = fmt.Fprintf(w, "unhealthy: %v\n", err)
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return
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}
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}
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w.WriteHeader(http.StatusOK)
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_, _ = fmt.Fprintln(w, "ok")
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})
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mux.HandleFunc("/ready", func(w http.ResponseWriter, r *http.Request) {
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h.mu.Lock()
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ready := h.ready
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h.mu.Unlock()
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if !ready {
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w.WriteHeader(http.StatusServiceUnavailable)
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_, _ = fmt.Fprintln(w, "not ready")
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return
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}
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w.WriteHeader(http.StatusOK)
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_, _ = fmt.Fprintln(w, "ready")
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})
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listener, err := net.Listen("tcp", h.addr)
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if err != nil {
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return coreerr.E("HealthServer.Start", fmt.Sprintf("failed to listen on %s", h.addr), err)
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}
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h.listener = listener
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h.server = &http.Server{Handler: mux}
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go func() {
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_ = h.server.Serve(listener)
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}()
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return nil
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}
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// Stop gracefully shuts down the health server.
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func (h *HealthServer) Stop(ctx context.Context) error {
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if h.server == nil {
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return nil
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}
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return h.server.Shutdown(ctx)
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}
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// Addr returns the actual address the server is listening on.
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func (h *HealthServer) Addr() string {
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if h.listener != nil {
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return h.listener.Addr().String()
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}
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return h.addr
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}
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// WaitForHealth polls a health endpoint until it responds 200 or the timeout
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// (in milliseconds) expires. Returns true if healthy, false on timeout.
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func WaitForHealth(addr string, timeoutMs int) bool {
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ok, _ := ProbeHealth(addr, timeoutMs)
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return ok
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}
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// ProbeHealth polls a health endpoint until it responds 200 or the timeout
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// (in milliseconds) expires. Returns the health status and the last observed
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// failure reason if the endpoint never becomes healthy.
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func ProbeHealth(addr string, timeoutMs int) (bool, string) {
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deadline := time.Now().Add(time.Duration(timeoutMs) * time.Millisecond)
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url := fmt.Sprintf("http://%s/health", addr)
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client := &http.Client{Timeout: 2 * time.Second}
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var lastReason string
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for time.Now().Before(deadline) {
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resp, err := client.Get(url)
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if err == nil {
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body, _ := io.ReadAll(resp.Body)
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_ = resp.Body.Close()
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if resp.StatusCode == http.StatusOK {
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return true, ""
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}
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lastReason = strings.TrimSpace(string(body))
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if lastReason == "" {
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lastReason = resp.Status
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}
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} else {
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lastReason = err.Error()
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}
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time.Sleep(200 * time.Millisecond)
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}
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if lastReason == "" {
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lastReason = "health check timed out"
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}
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return false, lastReason
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}
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