rob05c commented on code in PR #7096: URL: https://github.com/apache/trafficcontrol/pull/7096#discussion_r1003764401
########## tc-health-client/tmagent/markdownservice.go: ########## @@ -0,0 +1,484 @@ +package tmagent + +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +import ( + "bytes" + "errors" + "os/exec" + "path/filepath" + "strconv" + "time" + + "github.com/apache/trafficcontrol/lib/go-log" + "github.com/apache/trafficcontrol/lib/go-tc" + "github.com/apache/trafficcontrol/lib/go-util" + "github.com/apache/trafficcontrol/tc-health-client/config" +) + +// ParentStatus contains the trafficserver 'HostStatus' fields that +// are necessary to interface with the trafficserver 'traffic_ctl' command. +type ParentStatus struct { + Fqdn string + ActiveReason bool + LocalReason bool + ManualReason bool + LastTmPoll int64 + UnavailablePollCount int + MarkUpPollCount int +} + +// used to get the overall parent availablity from the +// HostStatus markdown reasons. all markdown reasons +// must be true for a parent to be considered available. +func (p ParentStatus) available(reasonCode string) bool { + rc := false + + switch reasonCode { + case "active": + rc = p.ActiveReason + case "local": + rc = p.LocalReason + case "manual": + rc = p.ManualReason + } + return rc +} + +// used to log that a parent's status is either UP or +// DOWN based upon the HostStatus reason codes. to +// be considered UP, all reason codes must be 'true'. +func (p ParentStatus) Status() string { + if !p.ActiveReason { + return "DOWN" + } else if !p.LocalReason { + return "DOWN" + } else if !p.ManualReason { + return "DOWN" + } + return "UP" +} + +type StatusReason int + +// these are the HostStatus reason codes used within +// trafficserver. +const ( + ACTIVE StatusReason = iota + LOCAL + MANUAL +) + +// used for logging a parent's HostStatus reason code +// setting. +func (s StatusReason) String() string { + switch s { + case ACTIVE: + return "ACTIVE" + case LOCAL: + return "LOCAL" + case MANUAL: + return "MANUAL" + } + return "UNDEFINED" +} + +// MarkdownServer contains symbols for manipulating a running MarkdownService +// started by StartMarkdownService. +type MarkdownServer struct { + // Shutdown signals the MarkdownService to stop its goroutines and release all resources. + // + // It is not buffered. Writes will block until the markdown service is done with any + // ongoing markdown operation. Once a write returns, the MarkdownService will begin + // shutdown. + // TODO: add signal to callers when shutdown has finished. + Shutdown chan<- struct{} + + // UpdateHealth signals to the markdown service that health status has changed, and it should process markdowns again. + UpdateHealth func() +} + +func StartMarkdownService(pi *ParentInfo, pollInterval time.Duration) *MarkdownServer { + doneCh := make(chan struct{}) + updateCh := make(chan struct{}) + updateHealthF := func() { + select { + case updateCh <- struct{}{}: + default: + } + } + + go markdownServicePoll(pi, pollInterval, doneCh, updateCh) + return &MarkdownServer{Shutdown: doneCh, UpdateHealth: updateHealthF} +} + +func markdownServicePoll(pi *ParentInfo, pollInterval time.Duration, doneChan <-chan struct{}, updateChan <-chan struct{}) { + for { + select { + case <-doneChan: + return + default: + <-updateChan + start := time.Now() + doMarkdown(pi) + log.Infof("poll-status poll=markdown ms=%v\n", int(time.Since(start)/time.Millisecond)) + time.Sleep(pollInterval) + } + } +} + +// decideHealthy is the algorithm for deciding whether a cache is healthy. +// It takes the cache hostname, and all health results, and returns a single boolean decision. +func decideHealthy( + markdownMethods map[config.HealthMethod]struct{}, + parentFQDN string, + tmHealth *TrafficMonitorHealth, + parentHealthL4 *ParentHealth, + parentHealthL7 *ParentHealth, + parentServiceHealth *ParentServiceHealth, +) bool { + // TODO use hostname:port? Parents can be healthy on one port/service but not another. + // The ATS markdown command can't mark down per-port as of this writing, but + // we can at least calculate it, to log that data, and be able to easily + // mark down host:port when ATS adds that. + + // note the CacheStatuses has v4 and v6 data, + // but ATS also can't mark down hosts per IP version yet, + // so we just use the generic/old non-IP-versioned IsAvailable field. + + // TODO make decision algorithm/pessimism/ratio/etc configurable + + tmHealthy := (*bool)(nil) + l4Healthy := (*bool)(nil) + l7Healthy := (*bool)(nil) + recursiveHealthy := (*bool)(nil) + + l4Health, hasL4Health := parentHealthL4.ParentHealthPollResults[parentFQDN] + l7Health, hasL7Health := parentHealthL7.ParentHealthPollResults[parentFQDN] + + if _, use := markdownMethods[config.HealthMethodTrafficMonitor]; use && tmHealth.CacheStatuses != nil { + parentHostName := parseFqdn(parentFQDN) + tmHealthy = util.BoolPtr(tmHealth.CacheStatuses[tc.CacheName(parentHostName)].IsAvailable) + } + if _, use := markdownMethods[config.HealthMethodParentL4]; use && parentHealthL4 != nil && hasL4Health && len(parentHealthL4.ParentHealthPollResults) > 0 { + l4Healthy = util.BoolPtr(l4Health.Healthy) + } + if _, use := markdownMethods[config.HealthMethodParentL7]; use && parentHealthL7 != nil && hasL7Health && len(parentHealthL7.ParentHealthPollResults) > 0 { + l7Healthy = util.BoolPtr(l7Health.Healthy) + } + if _, use := markdownMethods[config.HealthMethodParentService]; use && parentServiceHealth != nil && parentServiceHealth.ParentServiceHealthPollResults != nil { + recursiveHealthy = util.BoolPtr(decideRecursiveHealthy(parentServiceHealth.ParentServiceHealthPollResults[parentFQDN].ParentServiceHealth)) + } + + printbp := func(bp *bool) string { + if bp == nil { + return "nil" + } + return strconv.FormatBool(*bp) + } + + // TODO wait for all polls to have results, before marking down? + // Maybe it doesn't matter for pessimistic health? + + log.Infof("decide-healthy host=%v tm=%v l4=%v l7=%v svc=%v\n", parentFQDN, printbp(tmHealthy), printbp(l4Healthy), printbp(l7Healthy), printbp(recursiveHealthy)) + + // nilOrTrue is a helper func that returns true if the given *bool is nil or true. + // This is used for pessimistic health, but if the health doesn't exist for the parent + // for a particular health type poller, we don't want to mark it unhealthy. + nilOrTrue := func(bp *bool) bool { + return bp == nil || *bp + } + + // pessimistic: if any health mechanism is unhealthy, consider the host unhealthy + return nilOrTrue(tmHealthy) && nilOrTrue(l4Healthy) && nilOrTrue(l7Healthy) && nilOrTrue(recursiveHealthy) +} + +// decideRecursiveHealthy is the algorithm for deciding whether a parent is healthy, +// based on a heuristic of whether it can get to most parents +// It takes the cache hostname, and all health results, and returns a single boolean decision. +// +// Note this is a heuristic because ATS doesn't currently have the ability to mark down +// a parent hostname for a single remap. +// If and when ATS has the ability to mark down parents per-remap, we can mark down parents +// just for remaps whose origins aren't available on that parent. +func decideRecursiveHealthy(parentServiceHealth *ParentServiceHealth) bool { + // TODO get direct vs final parent data from strategies.yaml and parent.config + // Because we really want to heuristically check only the final parents (i.e. origins) + // are available on our direct parent, not any other origins it has that aren't assigned + // to this cache. + + // TODO make configurable + const ratioToConsiderHealthy = 0.5 + + parentHealthy := map[string]bool{} + + // TODO this is currently pessimistic: if any health mechanism is unhealthy, consider unhealthy. + // make health decision configurable. + + if parentServiceHealth == nil || parentServiceHealth.ParentServiceHealthPollResults == nil { + log.Warnln("decideRecursiveHealthy got nil parents, returning healthy") + return true + } + + for parentFQDN, recursiveHealth := range parentServiceHealth.ParentServiceHealthPollResults { + if recursiveHealth.ParentHealthL4 != nil && !recursiveHealth.ParentHealthL4.Healthy { + parentHealthy[parentFQDN] = false + continue + } + if recursiveHealth.ParentHealthL7 != nil && !recursiveHealth.ParentHealthL7.Healthy { + parentHealthy[parentFQDN] = false + continue + } + if !decideRecursiveHealthy(recursiveHealth.ParentServiceHealth.ParentServiceHealthPollResults[parentFQDN].ParentServiceHealth) { + parentHealthy[parentFQDN] = false + continue + } + parentHealthy[parentFQDN] = true + } + + numParents := 0 + numParentsHealthy := 0 + for _, healthy := range parentHealthy { + numParents++ + if healthy { + numParentsHealthy++ + } + } + healthyRatio := float64(numParentsHealthy) / float64(numParents) + return healthyRatio >= ratioToConsiderHealthy +} + +type parent struct { + host string + fqdn string +} + +// getParentFQDNs returns the FQDN of all parents in all health types. +// This is necessary, because some health polls might not have parents, so we need to combine them all +func getParentFQDNs(pi *ParentInfo, tmh *TrafficMonitorHealth, l4h *ParentHealth, l7h *ParentHealth, sh *ParentServiceHealth) []string { + + // put FQDns in a set first, to remove duplicates + fqdnSet := map[string]struct{}{} + + for cacheName, _ := range tmh.CacheStatuses { + hostName := string(cacheName) + fqdn, ok := pi.ParentHostFQDNs.Load(hostName) + if !ok { + // this should be normal. Many parents in TM won't be parents of this cache + continue + } + fqdnSet[fqdn] = struct{}{} + } + + for fqdn, _ := range l4h.ParentHealthPollResults { + fqdnSet[fqdn] = struct{}{} + } + for fqdn, _ := range l7h.ParentHealthPollResults { + fqdnSet[fqdn] = struct{}{} + } + for fqdn, _ := range sh.ParentServiceHealthPollResults { + // we don't need recursive health, just the direct parent. We only need direct parents to mark down. + fqdnSet[fqdn] = struct{}{} + } + + fqdns := make([]string, 0, len(fqdnSet)) + for fqdn, _ := range fqdnSet { + fqdns = append(fqdns, fqdn) + } + return fqdns +} + +// HealthSafetyRatio is the ratio of unhealthy parents after which no parents will be marked down. +// +// This is a safety mechanism: if for any reason most or all parents are marked down, something +// is seriously wrong, possibly with the health code itself, and therefore don't mark any parents down, +const HealthSafetyRatio = 0.3 // TODO make configurable? + +func doMarkdown(pi *ParentInfo) { + cfg := pi.Cfg.Get() + + tmHealth := pi.TrafficMonitorHealth.Get() + parentHealthL4 := pi.ParentHealthL4.Get() + parentHealthL7 := pi.ParentHealthL7.Get() + parentServiceHealth := pi.ParentServiceHealth.Get() + + parentFQDNs := getParentFQDNs(pi, tmHealth, parentHealthL4, parentHealthL7, parentServiceHealth) + unhealthyNum := 0 + newCacheHealth := map[string]bool{} // map[fqdn]healthy + for _, fqdn := range parentFQDNs { + newAvailable := decideHealthy(pi.MarkdownMethods, fqdn, tmHealth, parentHealthL4, parentHealthL7, parentServiceHealth) + if !newAvailable { + unhealthyNum++ + } + newCacheHealth[fqdn] = newAvailable + } + + unhealthyParentsExceedSafetyRatio := (float64(unhealthyNum) / float64(len(newCacheHealth))) > HealthSafetyRatio + log.Infof("markdown Unhealthy parents %v/%v safety ratio %v\n", unhealthyNum, len(newCacheHealth), HealthSafetyRatio) + if unhealthyParentsExceedSafetyRatio { + log.Errorf("Unhealthy parents %v/%v exceed safety ratio %v!! Marking all parents up!!\n", unhealthyNum, len(newCacheHealth), HealthSafetyRatio) + } + + for _, fqdn := range parentFQDNs { + isAvailable := tc.IsAvailable{} + { + hostName := parseFqdn(fqdn) + isAvailable = tmHealth.CacheStatuses[tc.CacheName(hostName)] + } + parentStatus, ok := pi.LoadParentStatus(fqdn) + if !ok { + continue // TODO warn? error? is this normal? + } + + // update the polling time + parentStatus.LastTmPoll = tmHealth.PollTime.Unix() + + newAvailable := newCacheHealth[fqdn] + if unhealthyParentsExceedSafetyRatio { + newAvailable = true + } + // newAvailable := isAvailable.IsAvailable + oldAvailable := parentStatus.available(cfg.ReasonCode) + if oldAvailable != newAvailable { + // do not mark down if the configuration disables mark downs. + if !cfg.EnableActiveMarkdowns && !newAvailable { + log.Infof("TM reports that %s is not available and should be marked DOWN but, mark downs are disabled by configuration", fqdn) + } else { + if newParentStatus, err := markParent(cfg, parentStatus, isAvailable.Status, newAvailable); err != nil { + log.Errorln(err.Error()) + } else { + log.Infoln("TM reports that '" + parentStatus.Fqdn + "' is not available so marked DOWN") + parentStatus = newParentStatus + } + } + } + + // if the host is available clear the unavailable poll count if not 0. + if oldAvailable && newAvailable { + if parentStatus.UnavailablePollCount > 0 { + log.Debugf("resetting the UnavailablePollCount for '%s' from %d to 0", + fqdn, parentStatus.UnavailablePollCount) + parentStatus.UnavailablePollCount = 0 + } + } + + { + parentHostName := parseFqdn(parentStatus.Fqdn) + pi.ParentHostFQDNs.Store(parentHostName, parentStatus.Fqdn) + } + + // even if the status wasn't updated, we always need to update the poll time on the ParentStatus + pi.StoreParentStatus(parentStatus.Fqdn, parentStatus) + } + +} + +// markParent is used to mark a parent as up or down in the trafficserver HostStatus subsystem. +// It takes a parent, modifies it by marking available and setting reasons and other data, +// and returns the modified/marked parent. +func markParent(cfg *config.Cfg, pv ParentStatus, cacheStatus string, available bool) (ParentStatus, error) { + var hostAvailable bool + + hostName := parseFqdn(pv.Fqdn) + + activeReason := pv.ActiveReason + localReason := pv.LocalReason + unavailablePollCount := pv.UnavailablePollCount + markUpPollCount := pv.MarkUpPollCount + + log.Debugf("hostName: %s, UnavailablePollCount: %d, available: %v", hostName, unavailablePollCount, available) + + if !available { // unavailable + unavailablePollCount += 1 + if unavailablePollCount < cfg.UnavailablePollThreshold { + log.Infof("TM indicates %s is unavailable but the UnavailablePollThreshold has not been reached", hostName) + hostAvailable = true + } else { + // marking the host down + if err := execTrafficCtl(pv.Fqdn, false, cfg.ReasonCode, cfg.TrafficServerBinDir); err != nil { + log.Errorln(err) + return ParentStatus{}, err + } + + hostAvailable = false + // reset the poll counts + markUpPollCount = 0 + unavailablePollCount = 0 + log.Infof("marked parent %s DOWN, cache status was: %s\n", hostName, cacheStatus) + } + } else { // available + // marking the host up + markUpPollCount += 1 + if markUpPollCount < cfg.MarkUpPollThreshold { + log.Infof("TM indicates %s is available but the MarkUpPollThreshold has not been reached", hostName) + hostAvailable = false + } else { + if err := execTrafficCtl(pv.Fqdn, true, cfg.ReasonCode, cfg.TrafficServerBinDir); err != nil { + log.Errorln(err) + return ParentStatus{}, err + } + hostAvailable = true + // reset the poll counts + unavailablePollCount = 0 + markUpPollCount = 0 + log.Infof("marked parent %s UP, cache status was: %s\n", hostName, cacheStatus) + } + } + + // update parent info + reason := cfg.ReasonCode + switch reason { + case "active": + activeReason = hostAvailable + case "local": + localReason = hostAvailable + } + // save updates + pv.ActiveReason = activeReason + pv.LocalReason = localReason + pv.UnavailablePollCount = unavailablePollCount + pv.MarkUpPollCount = markUpPollCount + // pi.Parents[hostName] = pv Review Comment: No, the func was changed to return parents rather than mutate state. 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