Rendering service - add optional RenderingSession (#44098)

* rendering service changes:
- make node-renderer request timeout configurable
- introduce optional RenderingSession providing a long-lived session key

* remove console logs

* added comment explaining empty "afterRequest" method

* fix compilation error

* update imports formatting

* Update pkg/services/rendering/interface.go

Co-authored-by: Agnès Toulet <35176601+AgnesToulet@users.noreply.github.com>

* Update pkg/services/rendering/rendering.go

Co-authored-by: Agnès Toulet <35176601+AgnesToulet@users.noreply.github.com>

* review fix: extract renderKey related functions/structs to auth.go

* #44449: private'd `rendering.getRequestTimeout`

Co-authored-by: Agnès Toulet <35176601+AgnesToulet@users.noreply.github.com>

pkg/services/rendering/auth.go

@@ -0,0 +1,120 @@
+package rendering
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/infra/remotecache"
+	"github.com/grafana/grafana/pkg/util"
+)
+
+const renderKeyPrefix = "render-%s"
+
+type RenderUser struct {
+	OrgID   int64
+	UserID  int64
+	OrgRole string
+}
+
+func (rs *RenderingService) GetRenderUser(ctx context.Context, key string) (*RenderUser, bool) {
+	val, err := rs.RemoteCacheService.Get(ctx, fmt.Sprintf(renderKeyPrefix, key))
+	if err != nil {
+		rs.log.Error("Failed to get render key from cache", "error", err)
+	}
+
+	if val != nil {
+		if user, ok := val.(*RenderUser); ok {
+			return user, true
+		}
+	}
+
+	return nil, false
+}
+
+func setRenderKey(cache *remotecache.RemoteCache, ctx context.Context, opts AuthOpts, renderKey string, expiry time.Duration) error {
+	err := cache.Set(ctx, fmt.Sprintf(renderKeyPrefix, renderKey), &RenderUser{
+		OrgID:   opts.OrgID,
+		UserID:  opts.UserID,
+		OrgRole: string(opts.OrgRole),
+	}, expiry)
+	return err
+}
+
+func generateAndSetRenderKey(cache *remotecache.RemoteCache, ctx context.Context, opts AuthOpts, expiry time.Duration) (string, error) {
+	key, err := util.GetRandomString(32)
+	if err != nil {
+		return "", err
+	}
+
+	err = setRenderKey(cache, ctx, opts, key, expiry)
+	if err != nil {
+		return "", err
+	}
+
+	return key, nil
+}
+
+type longLivedRenderKeyProvider struct {
+	cache       *remotecache.RemoteCache
+	log         log.Logger
+	renderKey   string
+	authOpts    AuthOpts
+	sessionOpts SessionOpts
+}
+
+func (rs *RenderingService) CreateRenderingSession(ctx context.Context, opts AuthOpts, sessionOpts SessionOpts) (Session, error) {
+	renderKey, err := generateAndSetRenderKey(rs.RemoteCacheService, ctx, opts, sessionOpts.Expiry)
+	if err != nil {
+		return nil, err
+	}
+
+	return &longLivedRenderKeyProvider{
+		log:         rs.log,
+		renderKey:   renderKey,
+		cache:       rs.RemoteCacheService,
+		authOpts:    opts,
+		sessionOpts: sessionOpts,
+	}, nil
+}
+
+func deleteRenderKey(cache *remotecache.RemoteCache, log log.Logger, ctx context.Context, renderKey string) {
+	err := cache.Delete(ctx, fmt.Sprintf(renderKeyPrefix, renderKey))
+	if err != nil {
+		log.Error("Failed to delete render key", "error", err)
+	}
+}
+
+type perRequestRenderKeyProvider struct {
+	cache     *remotecache.RemoteCache
+	log       log.Logger
+	keyExpiry time.Duration
+}
+
+func (r *perRequestRenderKeyProvider) get(ctx context.Context, opts AuthOpts) (string, error) {
+	return generateAndSetRenderKey(r.cache, ctx, opts, r.keyExpiry)
+}
+
+func (r *perRequestRenderKeyProvider) afterRequest(ctx context.Context, opts AuthOpts, renderKey string) {
+	deleteRenderKey(r.cache, r.log, ctx, renderKey)
+}
+
+func (r *longLivedRenderKeyProvider) get(ctx context.Context, opts AuthOpts) (string, error) {
+	if r.sessionOpts.RefreshExpiryOnEachRequest {
+		err := setRenderKey(r.cache, ctx, opts, r.renderKey, r.sessionOpts.Expiry)
+		if err != nil {
+			r.log.Error("Failed to refresh render key", "error", err, "renderKey", r.renderKey)
+		}
+	}
+	return r.renderKey, nil
+}
+
+func (r *longLivedRenderKeyProvider) afterRequest(ctx context.Context, opts AuthOpts, renderKey string) {
+	// do nothing - renderKey from longLivedRenderKeyProvider is deleted only after session expires
+	// or someone calls session.Dispose()
+}
+
+func (r *longLivedRenderKeyProvider) Dispose(ctx context.Context) {
+	deleteRenderKey(r.cache, r.log, ctx, r.renderKey)
+}