Return 200 for no hosts

Author: meiji163

go.mod

@@ -17,8 +17,12 @@ require (
 	vitess.io/vitess v2.1.1+incompatible
 )
 
+require github.com/stretchr/testify v1.3.0
+
 require (
+	github.com/davecgh/go-spew v1.1.0 // indirect
 	github.com/golang/protobuf v1.2.0 // indirect
 	github.com/hashicorp/go-immutable-radix v1.0.0 // indirect
 	github.com/hashicorp/golang-lru v0.5.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 )

go.sum

@@ -10,6 +10,7 @@ github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b h1:L/QXpzIa3pO
 github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b/go.mod h1:H0wQNHz2YrLsuXOZozoeDmnHXkNCRmMW0gwFWDfEZDA=
 github.com/circonus-labs/circonus-gometrics v2.3.1+incompatible/go.mod h1:nmEj6Dob7S7YxXgwXpfOuvO54S+tGdZdw9fuRZt25Ag=
 github.com/circonus-labs/circonusllhist v0.1.3/go.mod h1:kMXHVDlOchFAehlya5ePtbp5jckzBHf4XRpQvBOLI+I=
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-sql-driver/mysql v1.6.0 h1:BCTh4TKNUYmOmMUcQ3IipzF5prigylS7XXjEkfCHuOE=
 github.com/go-sql-driver/mysql v1.6.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
@@ -35,6 +36,7 @@ github.com/pascaldekloe/goe v0.1.0/go.mod h1:lzWF7FIEvWOWxwDKqyGYQf6ZUaNfKdP144T
 github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
 github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_golang v0.9.2/go.mod h1:OsXs2jCmiKlQ1lTBmv21f2mNfw4xf/QclQDMrYNZzcM=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
@@ -43,6 +45,7 @@ github.com/prometheus/procfs v0.0.0-20181204211112-1dc9a6cbc91a/go.mod h1:c3At6R
 github.com/rcrowley/go-metrics v0.0.0-20190826022208-cac0b30c2563 h1:dY6ETXrvDG7Sa4vE8ZQG4yqWg6UnOcbqTAahkV813vQ=
 github.com/rcrowley/go-metrics v0.0.0-20190826022208-cac0b30c2563/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/tv42/httpunix v0.0.0-20150427012821-b75d8614f926/go.mod h1:9ESjWnEqriFuLhtthL60Sar/7RFoluCcXsuvEwTV5KM=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=

pkg/base/throttle_metric.go

@@ -17,7 +17,7 @@ type MetricResult interface {
 type MetricResultFunc func() (metricResult MetricResult, threshold float64)
 
 var ThresholdExceededError = errors.New("Threshold exceeded")
-var noHostsError = errors.New("No hosts found")
+var NoHostsError = errors.New("No hosts found")
 var noResultYetError = errors.New("Metric not collected yet")
 var NoSuchMetricError = errors.New("No such metric")
 
@@ -31,7 +31,7 @@ func IsDialTcpError(e error) bool {
 type noHostsMetricResult struct{}
 
 func (metricResult *noHostsMetricResult) Get() (float64, error) {
-	return 0, noHostsError
+	return 0, NoHostsError
 }
 
 var NoHostsMetricResult = &noHostsMetricResult{}

pkg/mysql/mysql_inventory.go

@@ -7,6 +7,7 @@ package mysql
 
 import (
 	"fmt"
+
 	"github.com/github/freno/pkg/base"
 )
 

pkg/throttle/check.go

@@ -7,6 +7,8 @@ import (
 
 	"fmt"
 
+	"errors"
+
 	"github.com/github/freno/pkg/base"
 	metrics "github.com/rcrowley/go-metrics"
 )
@@ -65,6 +67,9 @@ func (check *ThrottlerCheck) checkAppMetricResult(appName string, storeType stri
 	} else if err == base.NoSuchMetricError {
 		// not collected yet, or metric does not exist
 		statusCode = http.StatusNotFound // 404
+	} else if errors.Is(err, base.NoHostsError) {
+		// If no hosts we report 0 for the metric.
+		statusCode = http.StatusOK // 200
 	} else if err != nil {
 		// any error
 		statusCode = http.StatusInternalServerError // 500

pkg/throttle/check_result.go

@@ -1,8 +1,9 @@
 package throttle
 
 import (
-	"github.com/github/freno/pkg/base"
 	"net/http"
+
+	"github.com/github/freno/pkg/base"
 )
 
 // CheckResult is the result for an app inquiring on a metric. It also exports as JSON via the API

vendor/github.com/patrickmn/go-cache/cache.go

@@ -10,6 +10,9 @@ github.com/boltdb/bolt
 # github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b
 ## explicit; go 1.12
 github.com/bradfitz/gomemcache/memcache
+# github.com/davecgh/go-spew v1.1.0
+## explicit
+github.com/davecgh/go-spew/spew
 # github.com/go-sql-driver/mysql v1.6.0
 ## explicit; go 1.10
 github.com/go-sql-driver/mysql
@@ -36,10 +39,16 @@ github.com/outbrain/golib/tests
 # github.com/patrickmn/go-cache v2.1.0+incompatible
 ## explicit
 github.com/patrickmn/go-cache
+# github.com/pmezard/go-difflib v1.0.0
+## explicit
+github.com/pmezard/go-difflib/difflib
 # github.com/rcrowley/go-metrics v0.0.0-20190826022208-cac0b30c2563
 ## explicit
 github.com/rcrowley/go-metrics
 github.com/rcrowley/go-metrics/exp
+# github.com/stretchr/testify v1.3.0
+## explicit
+github.com/stretchr/testify/assert
 # golang.org/x/sys v0.1.0
 ## explicit; go 1.17
 golang.org/x/sys/unix