bouncer/internal/proxy/director/layer/queue/queue.go

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package queue
import (
"context"
"fmt"
"html/template"
"math/rand"
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"net/http"
"path/filepath"
"strconv"
"sync"
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"sync/atomic"
"time"
"forge.cadoles.com/Cadoles/go-proxy"
"forge.cadoles.com/Cadoles/go-proxy/wildcard"
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"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
"forge.cadoles.com/cadoles/bouncer/internal/store"
"github.com/Masterminds/sprig/v3"
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"github.com/google/uuid"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
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"gitlab.com/wpetit/goweb/logger"
)
const LayerType store.LayerType = "queue"
type Queue struct {
adapter Adapter
defaultKeepAlive time.Duration
templateDir string
loadOnce sync.Once
tmpl *template.Template
refreshJobRunning uint32
updateMetricsJobRunning uint32
postKeepAliveDebouncer *DebouncerMap
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}
// LayerType implements director.MiddlewareLayer
func (q *Queue) LayerType() store.LayerType {
return LayerType
}
// Middleware implements director.MiddlewareLayer
func (q *Queue) Middleware(layer *store.Layer) proxy.Middleware {
return func(h http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
options, err := fromStoreOptions(layer.Options, q.defaultKeepAlive)
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if err != nil {
logger.Error(ctx, "could not parse layer options", logger.E(errors.WithStack(err)))
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
return
}
matches := wildcard.MatchAny(r.URL.String(), options.MatchURLs...)
if !matches {
h.ServeHTTP(w, r)
return
}
defer q.updateMetrics(ctx, layer.Proxy, layer.Name, options)
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cookieName := q.getCookieName(layer.Name)
cookie, err := r.Cookie(cookieName)
if err != nil && !errors.Is(err, http.ErrNoCookie) {
logger.Error(ctx, "could not retrieve cookie", logger.E(errors.WithStack(err)))
}
if cookie == nil {
cookie = &http.Cookie{
Name: cookieName,
Value: uuid.NewString(),
Path: "/",
}
w.Header().Add("Set-Cookie", cookie.String())
}
sessionID := cookie.Value
queueName := string(layer.Name)
rank, err := q.adapter.Touch(ctx, queueName, sessionID)
if err != nil {
logger.Error(ctx, "could not retrieve session rank", logger.E(errors.WithStack(err)))
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
return
}
if rank >= options.Capacity {
q.renderQueuePage(w, r, queueName, options, rank)
return
}
ctx = logger.With(ctx,
logger.F("queueSessionId", sessionID),
logger.F("queueName", queueName),
logger.F("queueSessionRank", rank),
)
r = r.WithContext(ctx)
h.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
}
func (q *Queue) updateSessionsMetric(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName) {
if !atomic.CompareAndSwapUint32(&q.updateMetricsJobRunning, 0, 1) {
return
}
defer atomic.StoreUint32(&q.updateMetricsJobRunning, 0)
queueName := string(layerName)
status, err := q.adapter.Status(ctx, queueName)
if err != nil {
logger.Error(ctx, "could not retrieve queue status", logger.E(errors.WithStack(err)))
return
}
metricQueueSessions.With(
prometheus.Labels{
metricLabelLayer: string(layerName),
metricLabelProxy: string(proxyName),
},
).Set(float64(status.Sessions))
}
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func (q *Queue) renderQueuePage(w http.ResponseWriter, r *http.Request, queueName string, options *LayerOptions, rank int64) {
ctx := r.Context()
status, err := q.adapter.Status(ctx, queueName)
if err != nil {
logger.Error(ctx, "could not retrieve queue status", logger.E(errors.WithStack(err)))
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
return
}
q.loadOnce.Do(func() {
pattern := filepath.Join(q.templateDir, "*.gohtml")
logger.Info(ctx, "loading queue page templates", logger.F("pattern", pattern))
tmpl, err := template.New("").Funcs(sprig.FuncMap()).ParseGlob(pattern)
if err != nil {
logger.Error(ctx, "could not load queue templates", logger.E(errors.WithStack(err)))
return
}
q.tmpl = tmpl
})
if q.tmpl == nil {
logger.Error(ctx, "queue page templates not loaded", logger.E(errors.WithStack(err)))
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
return
}
refreshRate := time.Duration(int64(options.KeepAlive.Seconds()/2)) * time.Second
templateData := struct {
QueueName string
LayerOptions *LayerOptions
Rank int64
CurrentSessions int64
MaxSessions int64
RefreshRate time.Duration
}{
QueueName: queueName,
LayerOptions: options,
Rank: rank + 1,
CurrentSessions: status.Sessions,
MaxSessions: options.Capacity,
RefreshRate: refreshRate,
}
w.Header().Add("Cache-Control", "no-cache")
w.Header().Add("Retry-After", strconv.FormatInt(int64(refreshRate.Seconds()), 10))
w.WriteHeader(http.StatusServiceUnavailable)
if err := q.tmpl.ExecuteTemplate(w, "queue", templateData); err != nil {
logger.Error(ctx, "could not render queue page", logger.E(errors.WithStack(err)))
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
return
}
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}
func (q *Queue) refreshQueue(ctx context.Context, layerName store.LayerName, keepAlive time.Duration) {
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if !atomic.CompareAndSwapUint32(&q.refreshJobRunning, 0, 1) {
return
}
defer atomic.StoreUint32(&q.refreshJobRunning, 0)
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if err := q.adapter.Refresh(ctx, string(layerName), keepAlive); err != nil {
logger.Error(ctx, "could not refresh queue",
logger.E(errors.WithStack(err)),
logger.F("queue", layerName),
)
}
}
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func (q *Queue) updateMetrics(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName, options *LayerOptions) {
// Update queue capacity metric
metricQueueCapacity.With(
prometheus.Labels{
metricLabelLayer: string(layerName),
metricLabelProxy: string(proxyName),
},
).Set(float64(options.Capacity))
// Refresh queue data and metrics
q.refreshQueue(ctx, layerName, options.KeepAlive)
q.updateSessionsMetric(ctx, proxyName, layerName)
// (Re)schedule an update job after session ttl + semi-random time padding
// to update metrics after last session expiration
randDuration := rand.Int63n(int64(options.KeepAlive))
timePadding := options.KeepAlive/2 + time.Duration(randDuration)
after := options.KeepAlive + timePadding
debouncingKey := fmt.Sprintf("%s/%s", proxyName, layerName)
q.postKeepAliveDebouncer.Do(debouncingKey, after, func() {
ctx := logger.With(
context.Background(),
logger.F("proxy", proxyName),
logger.F("layer", layerName),
logger.F("after", after),
)
logger.Info(ctx, "running post keep alive refresh job")
q.refreshQueue(ctx, layerName, options.KeepAlive)
q.updateSessionsMetric(ctx, proxyName, layerName)
})
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}
func (q *Queue) getCookieName(layerName store.LayerName) string {
return fmt.Sprintf("_bouncer_%s_%s", LayerType, layerName)
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}
func New(adapter Adapter, funcs ...OptionFunc) *Queue {
opts := defaultOptions()
for _, fn := range funcs {
fn(opts)
}
return &Queue{
adapter: adapter,
templateDir: opts.TemplateDir,
defaultKeepAlive: opts.DefaultKeepAlive,
postKeepAliveDebouncer: NewDebouncerMap(),
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}
}
var _ director.MiddlewareLayer = &Queue{}