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|
package observability
import (
"context"
"errors"
"fmt"
"net"
"net/http"
"net/http/pprof"
"sync"
"sync/atomic"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"gitlab.com/gitlab-org/cluster-integration/gitlab-agent/v16/internal/module/modshared"
"gitlab.com/gitlab-org/cluster-integration/gitlab-agent/v16/internal/tool/httpz"
"go.uber.org/zap"
)
const (
defaultMaxRequestDuration = 15 * time.Second
shutdownTimeout = defaultMaxRequestDuration
readTimeout = 1 * time.Second
writeTimeout = defaultMaxRequestDuration
idleTimeout = 1 * time.Minute
)
// Probe is the expected type for probe functions
type Probe func(context.Context) error
// NoopProbe is a placeholder probe for convenience
func NoopProbe(context.Context) error {
return nil
}
func NewProbeRegistry() *ProbeRegistry {
return &ProbeRegistry{
liveness: make(map[string]Probe),
readiness: make(map[string]Probe),
}
}
type ProbeRegistry struct {
mu sync.RWMutex
liveness map[string]Probe
readiness map[string]Probe
}
type toggleValue struct {
value int32
}
func (t *toggleValue) SetTrue() {
atomic.StoreInt32(&t.value, 1)
}
func (t *toggleValue) True() bool {
return atomic.LoadInt32(&t.value) == 1
}
func (p *ProbeRegistry) RegisterLivenessProbe(key string, probe Probe) {
p.mu.Lock()
defer p.mu.Unlock()
p.liveness[key] = probe
}
func (p *ProbeRegistry) RegisterReadinessProbe(key string, probe Probe) {
p.mu.Lock()
defer p.mu.Unlock()
p.readiness[key] = probe
}
func (p *ProbeRegistry) Liveness(ctx context.Context) error {
p.mu.RLock()
defer p.mu.RUnlock()
return execProbeMap(ctx, p.liveness)
}
func (p *ProbeRegistry) Readiness(ctx context.Context) error {
p.mu.RLock()
defer p.mu.RUnlock()
return execProbeMap(ctx, p.readiness)
}
func (p *ProbeRegistry) RegisterReadinessToggle(key string) func() {
var value toggleValue
p.RegisterReadinessProbe(key, func(ctx context.Context) error {
if value.True() {
return nil
}
return errors.New("not ready yet")
})
return value.SetTrue
}
func execProbeMap(ctx context.Context, probes map[string]Probe) error {
for key, probe := range probes {
err := probe(ctx)
if err != nil {
return fmt.Errorf("%s: %w", key, err)
}
}
return nil
}
type MetricServer struct {
Log *zap.Logger
Api modshared.Api
// Name is the name of the application.
Name string
Listener net.Listener
PrometheusUrlPath string
LivenessProbeUrlPath string
ReadinessProbeUrlPath string
Gatherer prometheus.Gatherer
Registerer prometheus.Registerer
ProbeRegistry *ProbeRegistry
}
func (s *MetricServer) Run(ctx context.Context) error {
srv := &http.Server{ // nolint: gosec
Handler: s.ConstructHandler(), // nolint: contextcheck
WriteTimeout: writeTimeout,
ReadTimeout: readTimeout,
IdleTimeout: idleTimeout,
}
return httpz.RunServer(ctx, srv, s.Listener, 0, shutdownTimeout)
}
func (s *MetricServer) ConstructHandler() http.Handler {
mux := http.NewServeMux()
s.probesHandler(mux) // nolint: contextcheck
s.pprofHandler(mux)
s.prometheusHandler(mux)
return mux
}
func (s *MetricServer) setHeader(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header()[httpz.ServerHeader] = []string{s.Name}
next.ServeHTTP(w, r)
})
}
func (s *MetricServer) probesHandler(mux *http.ServeMux) {
mux.Handle(
s.LivenessProbeUrlPath,
s.setHeader(http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
err := s.ProbeRegistry.Liveness(request.Context())
if err != nil {
s.logAndCapture(request.Context(), "LivenessProbe failed", err)
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusOK)
})),
)
mux.Handle(
s.ReadinessProbeUrlPath,
s.setHeader(http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
err := s.ProbeRegistry.Readiness(request.Context())
if err != nil {
s.logAndCapture(request.Context(), "ReadinessProbe failed", err)
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusOK)
})),
)
}
func (s *MetricServer) prometheusHandler(mux *http.ServeMux) {
mux.Handle(
s.PrometheusUrlPath,
s.setHeader(promhttp.InstrumentMetricHandler(s.Registerer, promhttp.HandlerFor(s.Gatherer, promhttp.HandlerOpts{
Timeout: defaultMaxRequestDuration,
}))),
)
}
func (s *MetricServer) pprofHandler(mux *http.ServeMux) {
routes := map[string]func(http.ResponseWriter, *http.Request){
"/debug/pprof/": pprof.Index,
"/debug/pprof/cmdline": pprof.Cmdline,
"/debug/pprof/profile": pprof.Profile,
"/debug/pprof/symbol": pprof.Symbol,
"/debug/pprof/trace": pprof.Trace,
}
for route, handler := range routes {
mux.Handle(route, s.setHeader(http.HandlerFunc(handler)))
}
}
func (s *MetricServer) logAndCapture(ctx context.Context, msg string, err error) {
s.Api.HandleProcessingError(ctx, s.Log, modshared.NoAgentId, msg, err)
}
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