Matthias Andreas Benkard | 832a54e | 2019-01-29 09:27:38 +0100 | [diff] [blame^] | 1 | /* |
| 2 | Copyright 2016 The Kubernetes Authors. |
| 3 | |
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | you may not use this file except in compliance with the License. |
| 6 | You may obtain a copy of the License at |
| 7 | |
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | Unless required by applicable law or agreed to in writing, software |
| 11 | distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | See the License for the specific language governing permissions and |
| 14 | limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package filters |
| 18 | |
| 19 | import ( |
| 20 | "fmt" |
| 21 | "net/http" |
| 22 | "sync" |
| 23 | "time" |
| 24 | |
| 25 | "k8s.io/apimachinery/pkg/util/sets" |
| 26 | "k8s.io/apimachinery/pkg/util/wait" |
| 27 | "k8s.io/apiserver/pkg/authentication/user" |
| 28 | "k8s.io/apiserver/pkg/endpoints/metrics" |
| 29 | apirequest "k8s.io/apiserver/pkg/endpoints/request" |
| 30 | |
| 31 | "github.com/golang/glog" |
| 32 | ) |
| 33 | |
| 34 | const ( |
| 35 | // Constant for the retry-after interval on rate limiting. |
| 36 | // TODO: maybe make this dynamic? or user-adjustable? |
| 37 | retryAfter = "1" |
| 38 | |
| 39 | // How often inflight usage metric should be updated. Because |
| 40 | // the metrics tracks maximal value over period making this |
| 41 | // longer will increase the metric value. |
| 42 | inflightUsageMetricUpdatePeriod = time.Second |
| 43 | ) |
| 44 | |
| 45 | var nonMutatingRequestVerbs = sets.NewString("get", "list", "watch") |
| 46 | |
| 47 | func handleError(w http.ResponseWriter, r *http.Request, err error) { |
| 48 | w.WriteHeader(http.StatusInternalServerError) |
| 49 | fmt.Fprintf(w, "Internal Server Error: %#v", r.RequestURI) |
| 50 | glog.Errorf(err.Error()) |
| 51 | } |
| 52 | |
| 53 | // requestWatermark is used to trak maximal usage of inflight requests. |
| 54 | type requestWatermark struct { |
| 55 | lock sync.Mutex |
| 56 | readOnlyWatermark, mutatingWatermark int |
| 57 | } |
| 58 | |
| 59 | func (w *requestWatermark) recordMutating(mutatingVal int) { |
| 60 | w.lock.Lock() |
| 61 | defer w.lock.Unlock() |
| 62 | |
| 63 | if w.mutatingWatermark < mutatingVal { |
| 64 | w.mutatingWatermark = mutatingVal |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | func (w *requestWatermark) recordReadOnly(readOnlyVal int) { |
| 69 | w.lock.Lock() |
| 70 | defer w.lock.Unlock() |
| 71 | |
| 72 | if w.readOnlyWatermark < readOnlyVal { |
| 73 | w.readOnlyWatermark = readOnlyVal |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | var watermark = &requestWatermark{} |
| 78 | |
| 79 | func startRecordingUsage() { |
| 80 | go func() { |
| 81 | wait.Forever(func() { |
| 82 | watermark.lock.Lock() |
| 83 | readOnlyWatermark := watermark.readOnlyWatermark |
| 84 | mutatingWatermark := watermark.mutatingWatermark |
| 85 | watermark.readOnlyWatermark = 0 |
| 86 | watermark.mutatingWatermark = 0 |
| 87 | watermark.lock.Unlock() |
| 88 | |
| 89 | metrics.UpdateInflightRequestMetrics(readOnlyWatermark, mutatingWatermark) |
| 90 | }, inflightUsageMetricUpdatePeriod) |
| 91 | }() |
| 92 | } |
| 93 | |
| 94 | var startOnce sync.Once |
| 95 | |
| 96 | // WithMaxInFlightLimit limits the number of in-flight requests to buffer size of the passed in channel. |
| 97 | func WithMaxInFlightLimit( |
| 98 | handler http.Handler, |
| 99 | nonMutatingLimit int, |
| 100 | mutatingLimit int, |
| 101 | longRunningRequestCheck apirequest.LongRunningRequestCheck, |
| 102 | ) http.Handler { |
| 103 | startOnce.Do(startRecordingUsage) |
| 104 | if nonMutatingLimit == 0 && mutatingLimit == 0 { |
| 105 | return handler |
| 106 | } |
| 107 | var nonMutatingChan chan bool |
| 108 | var mutatingChan chan bool |
| 109 | if nonMutatingLimit != 0 { |
| 110 | nonMutatingChan = make(chan bool, nonMutatingLimit) |
| 111 | } |
| 112 | if mutatingLimit != 0 { |
| 113 | mutatingChan = make(chan bool, mutatingLimit) |
| 114 | } |
| 115 | |
| 116 | return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { |
| 117 | ctx := r.Context() |
| 118 | requestInfo, ok := apirequest.RequestInfoFrom(ctx) |
| 119 | if !ok { |
| 120 | handleError(w, r, fmt.Errorf("no RequestInfo found in context, handler chain must be wrong")) |
| 121 | return |
| 122 | } |
| 123 | |
| 124 | // Skip tracking long running events. |
| 125 | if longRunningRequestCheck != nil && longRunningRequestCheck(r, requestInfo) { |
| 126 | handler.ServeHTTP(w, r) |
| 127 | return |
| 128 | } |
| 129 | |
| 130 | var c chan bool |
| 131 | isMutatingRequest := !nonMutatingRequestVerbs.Has(requestInfo.Verb) |
| 132 | if isMutatingRequest { |
| 133 | c = mutatingChan |
| 134 | } else { |
| 135 | c = nonMutatingChan |
| 136 | } |
| 137 | |
| 138 | if c == nil { |
| 139 | handler.ServeHTTP(w, r) |
| 140 | } else { |
| 141 | |
| 142 | select { |
| 143 | case c <- true: |
| 144 | var mutatingLen, readOnlyLen int |
| 145 | if isMutatingRequest { |
| 146 | mutatingLen = len(mutatingChan) |
| 147 | } else { |
| 148 | readOnlyLen = len(nonMutatingChan) |
| 149 | } |
| 150 | |
| 151 | defer func() { |
| 152 | <-c |
| 153 | if isMutatingRequest { |
| 154 | watermark.recordMutating(mutatingLen) |
| 155 | } else { |
| 156 | watermark.recordReadOnly(readOnlyLen) |
| 157 | } |
| 158 | |
| 159 | }() |
| 160 | handler.ServeHTTP(w, r) |
| 161 | |
| 162 | default: |
| 163 | // We need to split this data between buckets used for throttling. |
| 164 | if isMutatingRequest { |
| 165 | metrics.DroppedRequests.WithLabelValues(metrics.MutatingKind).Inc() |
| 166 | } else { |
| 167 | metrics.DroppedRequests.WithLabelValues(metrics.ReadOnlyKind).Inc() |
| 168 | } |
| 169 | // at this point we're about to return a 429, BUT not all actors should be rate limited. A system:master is so powerful |
| 170 | // that they should always get an answer. It's a super-admin or a loopback connection. |
| 171 | if currUser, ok := apirequest.UserFrom(ctx); ok { |
| 172 | for _, group := range currUser.GetGroups() { |
| 173 | if group == user.SystemPrivilegedGroup { |
| 174 | handler.ServeHTTP(w, r) |
| 175 | return |
| 176 | } |
| 177 | } |
| 178 | } |
| 179 | metrics.Record(r, requestInfo, "", http.StatusTooManyRequests, 0, 0) |
| 180 | tooManyRequests(r, w) |
| 181 | } |
| 182 | } |
| 183 | }) |
| 184 | } |
| 185 | |
| 186 | func tooManyRequests(req *http.Request, w http.ResponseWriter) { |
| 187 | // Return a 429 status indicating "Too Many Requests" |
| 188 | w.Header().Set("Retry-After", retryAfter) |
| 189 | http.Error(w, "Too many requests, please try again later.", http.StatusTooManyRequests) |
| 190 | } |