Files
web/health/handler.go
Rene Nochebuena c4ef1948f6 feat(web): initial implementation — server, mw, httputil, health (v1.0.0)
Introduces code.nochebuena.dev/einherjar/web — the HTTP transport layer of the
Einherjar framework. Absorbs httpserver, httpmw, and httputil from micro-lib,
replacing gorilla/mux with chi, adopting SecurityBag-native middleware, and
centralizing error handling through a single httputil.Error function.

server:
- Server interface — embeds lifecycle.Component and chi.Router
- Config struct (EINHERJAR_SERVER_* env vars); DefaultConfig
- New(logger, cfg, opts...) Server; WithMiddleware option
- Binds TCP synchronously in OnStart; logs "server: listening" on success
- Graceful shutdown within ShutdownTimeout on OnStop

mw:
- Recover — catches panics, returns 500, logs at Error
- RequestID — injects UUID v7 (UUID v4 fallback) into context and X-Request-ID header
- RequestLogger — structured access log per request
- CORS / CORSAllowAll — chi-based, applied only when origins non-empty
- IPRateLimit / UserRateLimit — pluggable RateLimiterStore interface
- InMemoryRateLimiterStore — token-bucket backed by golang.org/x/time/rate;
  background goroutine evicts stale entries every 5 minutes
- StatusRecorder — wraps ResponseWriter to capture HTTP status code

httputil:
- Handle[Req, Res] / HandleNoBody[Res] / HandleEmpty[Req] — generic handler adapters
- Error(logger, w, r, err) — derives log level from status (≥500→Error, 4xx→Warn,
  499→Info); writes standardized JSON body; logz enriches *xerrors.Err automatically
- JSON(w, status, v) / NoContent(w) — response helpers
- HandlerFunc adapter type

health:
- NewHandler / NewHandlerWithConfig — runs all Checkable checks concurrently;
  returns JSON {status, components} with per-component latency and error
- Config struct (EINHERJAR_HEALTH_CHECK_TIMEOUT, default 5s)

Root factory:
- web.New(logger, cfg...) Server — composes Recover+RequestID+RequestLogger+CORS
  in outermost-first order; CORS applied only when AllowedOrigins non-empty

- server.Server interface and web/server/identifiable.go: embeds observability.Identifiable;
  ModulePath and ModuleVersion read via runtime/debug.ReadBuildInfo() — prints in launcher banner
2026-05-29 15:48:11 +00:00

103 lines
2.6 KiB
Go

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