103 lines
2.6 KiB
Go
103 lines
2.6 KiB
Go
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package health
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import (
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"context"
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"encoding/json"
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"net/http"
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"time"
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"code.nochebuena.dev/einherjar/contracts/logging"
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"code.nochebuena.dev/einherjar/contracts/observability"
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)
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type checkResult struct {
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name string
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status ComponentStatus
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priority observability.Level
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}
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type handler struct {
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logger logging.Logger
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checks []observability.Checkable
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timeout time.Duration
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}
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// NewHandler returns an http.Handler for the health endpoint with default configuration.
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// Runs all checks concurrently within a 5-second timeout.
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// Returns 200 (UP / DEGRADED) or 503 (DOWN).
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func NewHandler(logger logging.Logger, checks ...observability.Checkable) http.Handler {
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return NewHandlerWithConfig(logger, Config{}, checks...)
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}
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// NewHandlerWithConfig returns an http.Handler configured by cfg.
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// If cfg.CheckTimeout is zero the default (5 seconds) is applied.
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func NewHandlerWithConfig(logger logging.Logger, cfg Config, checks ...observability.Checkable) http.Handler {
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timeout := cfg.CheckTimeout
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if timeout == 0 {
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timeout = defaultCheckTimeout
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}
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return &handler{logger: logger, checks: checks, timeout: timeout}
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}
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func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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reqLogger := h.logger.WithContext(r.Context())
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reqLogger.Debug("health: running checks", "count", len(h.checks))
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ctx, cancel := context.WithTimeout(r.Context(), h.timeout)
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defer cancel()
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resChan := make(chan checkResult, len(h.checks))
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for _, chk := range h.checks {
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go func(c observability.Checkable) {
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start := time.Now()
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err := c.HealthCheck(ctx)
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latency := time.Since(start).String()
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status := "UP"
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errMsg := ""
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if err != nil {
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errMsg = err.Error()
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if c.Priority() == observability.LevelDegraded {
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status = "DEGRADED"
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} else {
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status = "DOWN"
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}
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}
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resChan <- checkResult{
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name: c.Name(),
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priority: c.Priority(),
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status: ComponentStatus{
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Status: status,
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Latency: latency,
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Error: errMsg,
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},
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}
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}(chk)
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}
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overallStatus := "UP"
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httpStatus := http.StatusOK
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components := make(map[string]ComponentStatus, len(h.checks))
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for range h.checks {
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res := <-resChan
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components[res.name] = res.status
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switch res.status.Status {
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case "DOWN":
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overallStatus = "DOWN"
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httpStatus = http.StatusServiceUnavailable
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case "DEGRADED":
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if overallStatus == "UP" {
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overallStatus = "DEGRADED"
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}
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}
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}
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resp := Response{Status: overallStatus, Components: components}
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w.Header().Set("Content-Type", "application/json")
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w.WriteHeader(httpStatus)
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if err := json.NewEncoder(w).Encode(resp); err != nil {
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reqLogger.Error("health: failed to encode response", err)
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}
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}
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