Add configurable file-existence and HTTP health checks
Add a section to the config file called "health". Within this section, "filecheckers" and "httpcheckers" list checks to run. Each check specifies a file or URI, a time interval for the check, and a threshold specifying how many times the check must fail to reach an unhealthy state. Document the new options in docs/configuration.md. Add unit testing for both types of checkers. Add an UnregisterAll function in the health package to support the unit tests, and an Unregister function for consistency with Register. Fix a string conversion problem in the health package's HTTP checker. Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
This commit is contained in:
Aaron Lehmann
parent
0189e8c218
commit
c48e460933
@ -15,6 +15,7 @@ import (
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"github.com/docker/distribution/configuration"
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ctxu "github.com/docker/distribution/context"
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"github.com/docker/distribution/health"
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"github.com/docker/distribution/health/checks"
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"github.com/docker/distribution/notifications"
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"github.com/docker/distribution/registry/api/errcode"
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"github.com/docker/distribution/registry/api/v2"
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@ -37,6 +38,9 @@ import (
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// was specified.
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const randomSecretSize = 32
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// defaultCheckInterval is the default time in between health checks
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const defaultCheckInterval = 10 * time.Second
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// App is a global registry application object. Shared resources can be placed
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// on this object that will be accessible from all requests. Any writable
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// fields should be protected.
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@ -231,10 +235,38 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
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// implementing this properly will require a refactor. This method may panic
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// if called twice in the same process.
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func (app *App) RegisterHealthChecks() {
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health.RegisterPeriodicThresholdFunc("storagedriver_"+app.Config.Storage.Type(), 10*time.Second, 3, func() error {
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health.RegisterPeriodicThresholdFunc("storagedriver_"+app.Config.Storage.Type(), defaultCheckInterval, 3, func() error {
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_, err := app.driver.List(app, "/") // "/" should always exist
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return err // any error will be treated as failure
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})
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for _, fileChecker := range app.Config.Health.FileCheckers {
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interval := fileChecker.Interval
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if interval == 0 {
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interval = defaultCheckInterval
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}
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if fileChecker.Threshold != 0 {
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ctxu.GetLogger(app).Infof("configuring file health check path=%s, interval=%d, threshold=%d", fileChecker.File, interval/time.Second, fileChecker.Threshold)
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health.Register(fileChecker.File, health.PeriodicThresholdChecker(checks.FileChecker(fileChecker.File), interval, fileChecker.Threshold))
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} else {
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ctxu.GetLogger(app).Infof("configuring file health check path=%s, interval=%d", fileChecker.File, interval/time.Second)
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health.Register(fileChecker.File, health.PeriodicChecker(checks.FileChecker(fileChecker.File), interval))
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}
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}
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for _, httpChecker := range app.Config.Health.HTTPCheckers {
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interval := httpChecker.Interval
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if interval == 0 {
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interval = defaultCheckInterval
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}
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if httpChecker.Threshold != 0 {
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ctxu.GetLogger(app).Infof("configuring HTTP health check uri=%s, interval=%d, threshold=%d", httpChecker.URI, interval/time.Second, httpChecker.Threshold)
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health.Register(httpChecker.URI, health.PeriodicThresholdChecker(checks.HTTPChecker(httpChecker.URI), interval, httpChecker.Threshold))
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} else {
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ctxu.GetLogger(app).Infof("configuring HTTP health check uri=%s, interval=%d", httpChecker.URI, interval/time.Second)
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health.Register(httpChecker.URI, health.PeriodicChecker(checks.HTTPChecker(httpChecker.URI), interval))
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}
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}
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}
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// register a handler with the application, by route name. The handler will be
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200
docs/handlers/health_test.go
Normal file
200
docs/handlers/health_test.go
Normal file
@ -0,0 +1,200 @@
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package handlers
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import (
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"encoding/json"
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"io/ioutil"
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"net/http"
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"net/http/httptest"
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"os"
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"testing"
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"time"
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"github.com/docker/distribution/configuration"
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"github.com/docker/distribution/health"
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"golang.org/x/net/context"
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)
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func TestFileHealthCheck(t *testing.T) {
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// In case other tests registered checks before this one
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health.UnregisterAll()
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interval := time.Second
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tmpfile, err := ioutil.TempFile(os.TempDir(), "healthcheck")
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if err != nil {
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t.Fatalf("could not create temporary file: %v", err)
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}
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defer tmpfile.Close()
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config := configuration.Configuration{
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Storage: configuration.Storage{
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"inmemory": configuration.Parameters{},
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},
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Health: configuration.Health{
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FileCheckers: []configuration.FileChecker{
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{
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Interval: interval,
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File: tmpfile.Name(),
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},
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},
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},
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}
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ctx := context.Background()
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app := NewApp(ctx, config)
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app.RegisterHealthChecks()
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debugServer := httptest.NewServer(nil)
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// Wait for health check to happen
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<-time.After(2 * interval)
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resp, err := http.Get(debugServer.URL + "/debug/health")
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if err != nil {
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t.Fatalf("error performing HTTP GET: %v", err)
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}
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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t.Fatalf("error reading HTTP body: %v", err)
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}
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resp.Body.Close()
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var decoded map[string]string
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err = json.Unmarshal(body, &decoded)
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if err != nil {
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t.Fatalf("error unmarshaling json: %v", err)
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}
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if len(decoded) != 1 {
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t.Fatal("expected 1 item in returned json")
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}
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if decoded[tmpfile.Name()] != "file exists" {
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t.Fatal(`did not get "file exists" result for health check`)
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}
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os.Remove(tmpfile.Name())
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<-time.After(2 * interval)
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resp, err = http.Get(debugServer.URL + "/debug/health")
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if err != nil {
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t.Fatalf("error performing HTTP GET: %v", err)
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}
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body, err = ioutil.ReadAll(resp.Body)
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if err != nil {
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t.Fatalf("error reading HTTP body: %v", err)
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}
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resp.Body.Close()
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var decoded2 map[string]string
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err = json.Unmarshal(body, &decoded2)
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if err != nil {
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t.Fatalf("error unmarshaling json: %v", err)
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}
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if len(decoded2) != 0 {
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t.Fatal("expected 0 items in returned json")
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}
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}
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func TestHTTPHealthCheck(t *testing.T) {
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// In case other tests registered checks before this one
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health.UnregisterAll()
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interval := time.Second
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threshold := 3
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stopFailing := make(chan struct{})
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checkedServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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if r.Method != "HEAD" {
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t.Fatalf("expected HEAD request, got %s", r.Method)
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}
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select {
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case <-stopFailing:
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w.WriteHeader(http.StatusOK)
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default:
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w.WriteHeader(http.StatusInternalServerError)
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}
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}))
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config := configuration.Configuration{
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Storage: configuration.Storage{
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"inmemory": configuration.Parameters{},
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},
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Health: configuration.Health{
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HTTPCheckers: []configuration.HTTPChecker{
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{
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Interval: interval,
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URI: checkedServer.URL,
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Threshold: threshold,
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},
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},
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},
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}
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ctx := context.Background()
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app := NewApp(ctx, config)
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app.RegisterHealthChecks()
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debugServer := httptest.NewServer(nil)
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for i := 0; ; i++ {
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<-time.After(interval)
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resp, err := http.Get(debugServer.URL + "/debug/health")
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if err != nil {
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t.Fatalf("error performing HTTP GET: %v", err)
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}
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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t.Fatalf("error reading HTTP body: %v", err)
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}
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resp.Body.Close()
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var decoded map[string]string
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err = json.Unmarshal(body, &decoded)
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if err != nil {
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t.Fatalf("error unmarshaling json: %v", err)
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}
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if i < threshold-1 {
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// definitely shouldn't have hit the threshold yet
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if len(decoded) != 0 {
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t.Fatal("expected 1 items in returned json")
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}
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continue
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}
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if i < threshold+1 {
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// right on the threshold - don't expect a failure yet
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continue
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}
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if len(decoded) != 1 {
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t.Fatal("expected 1 item in returned json")
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}
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if decoded[checkedServer.URL] != "downstream service returned unexpected status: 500" {
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t.Fatal("did not get expected result for health check")
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}
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break
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}
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// Signal HTTP handler to start returning 200
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close(stopFailing)
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<-time.After(2 * interval)
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resp, err := http.Get(debugServer.URL + "/debug/health")
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if err != nil {
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t.Fatalf("error performing HTTP GET: %v", err)
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}
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body, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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t.Fatalf("error reading HTTP body: %v", err)
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}
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resp.Body.Close()
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var decoded map[string]string
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err = json.Unmarshal(body, &decoded)
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if err != nil {
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t.Fatalf("error unmarshaling json: %v", err)
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}
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if len(decoded) != 0 {
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t.Fatal("expected 0 items in returned json")
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}
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}
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