aws: log when multiple subnets found for the same availability zone

Signed-off-by: Alexander Yastrebov <[email protected]>

aws/adapter.go

@@ -3,6 +3,7 @@ package aws
 import (
  "errors"
  "fmt"
+ "sort"
  "strings"
  "time"
 
@@ -915,47 +916,49 @@ func (a *Adapter) FindLBSubnets(scheme string) []string {
  internal = true
  }
 
- subnetsByAZ := make(map[string]*subnetDetails)
+ subnetsByAZ := make(map[string][]*subnetDetails)
  for _, subnet := range a.manifest.subnets {
  // ignore private subnet for public LB
  if !internal && !subnet.public {
  continue
  }
+ subnetsByAZ[subnet.availabilityZone] = append(subnetsByAZ[subnet.availabilityZone], subnet)
+ }
 
- existing, ok := subnetsByAZ[subnet.availabilityZone]
- if !ok {
- subnetsByAZ[subnet.availabilityZone] = subnet
- continue
- }
+ for _, subnets := range subnetsByAZ {
+ sort.Slice(subnets, func(a, b int) bool {
+ subnetA, subnetB := subnets[a], subnets[b]
 
- // prefer subnet with an elb role tag
- var tagName string
- if internal {
- tagName = internalELBRoleTagName
- } else {
- tagName = elbRoleTagName
- }
+ // prefer subnet with an elb role tag
+ tagName := elbRoleTagName
+ if internal {
+ tagName = internalELBRoleTagName
+ }
 
- _, existingHasTag := existing.tags[tagName]
- _, subnetHasTag := subnet.tags[tagName]
+  _, subnetAHasTag := subnetA.tags[tagName]
+  _, sunbetBHasTag := subnetB.tags[tagName]
 
- if existingHasTag != subnetHasTag {
- if subnetHasTag {
- subnetsByAZ[subnet.availabilityZone] = subnet
+ if subnetAHasTag != sunbetBHasTag {
+ if subnetAHasTag {
+ return true
+ }
  }
- continue
- }
 
- // If we have two subnets for the same AZ we arbitrarily choose
- // the one that is first lexicographically.
- if strings.Compare(existing.id, subnet.id) > 0 {
- subnetsByAZ[subnet.availabilityZone] = subnet
- }
+ // If we have two subnets for the same AZ we arbitrarily choose
+ // the one that is first lexicographically.
+ if subnetA.id < subnetB.id {
+ return true
+ }
+ return false
+ })
  }
 
  subnetIDs := make([]string, 0, len(subnetsByAZ))
- for _, subnet := range subnetsByAZ {
- subnetIDs = append(subnetIDs, subnet.id)
+ for az, subnets := range subnetsByAZ {
+ if len(subnets) > 1 {
+ log.Warnf("Found multiple subnets %v for availability zone %s, using %s", subnets, az, subnets[0].id)
+ }
+ subnetIDs = append(subnetIDs, subnets[0].id)
  }
 
  return subnetIDs

aws/adapter_test.go

@@ -704,6 +704,23 @@ func TestFindLBSubnets(tt *testing.T) {
  scheme: elbv2.LoadBalancerSchemeEnumInternetFacing,
  expectedSubnets: []string{"1"},
  },
+ {
+ name: "should select first lexicographically subnet when two match a single zone (regardless of details order)",
+ subnets: []*subnetDetails{
+ {
+ availabilityZone: "a",
+ public: true,
+ id: "1",
+ },
+ {
+ availabilityZone: "a",
+ public: true,
+ id: "2",
+ },
+ },
+ scheme: elbv2.LoadBalancerSchemeEnumInternetFacing,
+ expectedSubnets: []string{"1"},
+ },
  {
  name: "should not use internal subnets for public LB",
  subnets: []*subnetDetails{