sdk/go/health/aggregator.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: Apache-2.0
   4
   5 package health
   6
   7 import (
   8         "context"
   9         "encoding/json"
  10         "errors"
  11         "fmt"
  12         "net/http"
  13         "net/url"
  14         "sync"
  15         "time"
  16
  17         "git.arvados.org/arvados.git/sdk/go/arvados"
  18         "git.arvados.org/arvados.git/sdk/go/auth"
  19 )
  20
  21 const defaultTimeout = arvados.Duration(2 * time.Second)
  22
  23 // Aggregator implements http.Handler. It handles "GET /_health/all"
  24 // by checking the health of all configured services on the cluster
  25 // and responding 200 if everything is healthy.
  26 type Aggregator struct {
  27         setupOnce  sync.Once
  28         httpClient *http.Client
  29         timeout    arvados.Duration
  30
  31         Cluster *arvados.Cluster
  32
  33         // If non-nil, Log is called after handling each request.
  34         Log func(*http.Request, error)
  35 }
  36
  37 func (agg *Aggregator) setup() {
  38         agg.httpClient = http.DefaultClient
  39         if agg.timeout == 0 {
  40                 // this is always the case, except in the test suite
  41                 agg.timeout = defaultTimeout
  42         }
  43 }
  44
  45 func (agg *Aggregator) CheckHealth() error {
  46         return nil
  47 }
  48
  49 func (agg *Aggregator) Done() <-chan struct{} {
  50         return nil
  51 }
  52
  53 func (agg *Aggregator) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
  54         agg.setupOnce.Do(agg.setup)
  55         sendErr := func(statusCode int, err error) {
  56                 resp.WriteHeader(statusCode)
  57                 json.NewEncoder(resp).Encode(map[string]string{"error": err.Error()})
  58                 if agg.Log != nil {
  59                         agg.Log(req, err)
  60                 }
  61         }
  62
  63         resp.Header().Set("Content-Type", "application/json")
  64
  65         if !agg.checkAuth(req) {
  66                 sendErr(http.StatusUnauthorized, errUnauthorized)
  67                 return
  68         }
  69         if req.URL.Path == "/_health/all" {
  70                 json.NewEncoder(resp).Encode(agg.ClusterHealth())
  71         } else if req.URL.Path == "/_health/ping" {
  72                 resp.Write(healthyBody)
  73         } else {
  74                 sendErr(http.StatusNotFound, errNotFound)
  75                 return
  76         }
  77         if agg.Log != nil {
  78                 agg.Log(req, nil)
  79         }
  80 }
  81
  82 type ClusterHealthResponse struct {
  83         // "OK" if all needed services are OK, otherwise "ERROR".
  84         Health string `json:"health"`
  85
  86         // An entry for each known health check of each known instance
  87         // of each needed component: "instance of service S on node N
  88         // reports health-check C is OK."
  89         Checks map[string]CheckResult `json:"checks"`
  90
  91         // An entry for each service type: "service S is OK." This
  92         // exposes problems that can't be expressed in Checks, like
  93         // "service S is needed, but isn't configured to run
  94         // anywhere."
  95         Services map[arvados.ServiceName]ServiceHealth `json:"services"`
  96 }
  97
  98 type CheckResult struct {
  99         Health         string                 `json:"health"`
 100         Error          string                 `json:"error,omitempty"`
 101         HTTPStatusCode int                    `json:",omitempty"`
 102         HTTPStatusText string                 `json:",omitempty"`
 103         Response       map[string]interface{} `json:"response"`
 104         ResponseTime   json.Number            `json:"responseTime"`
 105 }
 106
 107 type ServiceHealth struct {
 108         Health string `json:"health"`
 109         N      int    `json:"n"`
 110 }
 111
 112 func (agg *Aggregator) ClusterHealth() ClusterHealthResponse {
 113         agg.setupOnce.Do(agg.setup)
 114         resp := ClusterHealthResponse{
 115                 Health:   "OK",
 116                 Checks:   make(map[string]CheckResult),
 117                 Services: make(map[arvados.ServiceName]ServiceHealth),
 118         }
 119
 120         mtx := sync.Mutex{}
 121         wg := sync.WaitGroup{}
 122         for svcName, svc := range agg.Cluster.Services.Map() {
 123                 // Ensure svc is listed in resp.Services.
 124                 mtx.Lock()
 125                 if _, ok := resp.Services[svcName]; !ok {
 126                         resp.Services[svcName] = ServiceHealth{Health: "ERROR"}
 127                 }
 128                 mtx.Unlock()
 129
 130                 for addr := range svc.InternalURLs {
 131                         wg.Add(1)
 132                         go func(svcName arvados.ServiceName, addr arvados.URL) {
 133                                 defer wg.Done()
 134                                 var result CheckResult
 135                                 pingURL, err := agg.pingURL(addr)
 136                                 if err != nil {
 137                                         result = CheckResult{
 138                                                 Health: "ERROR",
 139                                                 Error:  err.Error(),
 140                                         }
 141                                 } else {
 142                                         result = agg.ping(pingURL)
 143                                 }
 144
 145                                 mtx.Lock()
 146                                 defer mtx.Unlock()
 147                                 resp.Checks[fmt.Sprintf("%s+%s", svcName, pingURL)] = result
 148                                 if result.Health == "OK" {
 149                                         h := resp.Services[svcName]
 150                                         h.N++
 151                                         h.Health = "OK"
 152                                         resp.Services[svcName] = h
 153                                 } else {
 154                                         resp.Health = "ERROR"
 155                                 }
 156                         }(svcName, addr)
 157                 }
 158         }
 159         wg.Wait()
 160
 161         // Report ERROR if a needed service didn't fail any checks
 162         // merely because it isn't configured to run anywhere.
 163         for _, sh := range resp.Services {
 164                 if sh.Health != "OK" {
 165                         resp.Health = "ERROR"
 166                         break
 167                 }
 168         }
 169         return resp
 170 }
 171
 172 func (agg *Aggregator) pingURL(svcURL arvados.URL) (*url.URL, error) {
 173         base := url.URL(svcURL)
 174         return base.Parse("/_health/ping")
 175 }
 176
 177 func (agg *Aggregator) ping(target *url.URL) (result CheckResult) {
 178         t0 := time.Now()
 179
 180         var err error
 181         defer func() {
 182                 result.ResponseTime = json.Number(fmt.Sprintf("%.6f", time.Since(t0).Seconds()))
 183                 if err != nil {
 184                         result.Health, result.Error = "ERROR", err.Error()
 185                 } else {
 186                         result.Health = "OK"
 187                 }
 188         }()
 189
 190         req, err := http.NewRequest("GET", target.String(), nil)
 191         if err != nil {
 192                 return
 193         }
 194         req.Header.Set("Authorization", "Bearer "+agg.Cluster.ManagementToken)
 195
 196         ctx, cancel := context.WithTimeout(req.Context(), time.Duration(agg.timeout))
 197         defer cancel()
 198         req = req.WithContext(ctx)
 199         resp, err := agg.httpClient.Do(req)
 200         if err != nil {
 201                 return
 202         }
 203         result.HTTPStatusCode = resp.StatusCode
 204         result.HTTPStatusText = resp.Status
 205         err = json.NewDecoder(resp.Body).Decode(&result.Response)
 206         if err != nil {
 207                 err = fmt.Errorf("cannot decode response: %s", err)
 208         } else if resp.StatusCode != http.StatusOK {
 209                 err = fmt.Errorf("HTTP %d %s", resp.StatusCode, resp.Status)
 210         } else if h, _ := result.Response["health"].(string); h != "OK" {
 211                 if e, ok := result.Response["error"].(string); ok && e != "" {
 212                         err = errors.New(e)
 213                 } else {
 214                         err = fmt.Errorf("health=%q in ping response", h)
 215                 }
 216         }
 217         return
 218 }
 219
 220 func (agg *Aggregator) checkAuth(req *http.Request) bool {
 221         creds := auth.CredentialsFromRequest(req)
 222         for _, token := range creds.Tokens {
 223                 if token != "" && token == agg.Cluster.ManagementToken {
 224                         return true
 225                 }
 226         }
 227         return false
 228 }