Merge pull request kubernetes-sigs#2217 from Shreya027/main

Add code for acquiring region from env; Refactor code to reduce EC2 c…

Author: k8s-ci-robot

pkg/aws/cloud.go

@@ -6,6 +6,7 @@ import (
 "github.com/aws/aws-sdk-go/aws/session"
 "github.com/pkg/errors"
 "github.com/prometheus/client_golang/prometheus"
+"os"
 "sigs.k8s.io/aws-load-balancer-controller/pkg/aws/metrics"
 "sigs.k8s.io/aws-load-balancer-controller/pkg/aws/services"
 "sigs.k8s.io/aws-load-balancer-controller/pkg/aws/throttle"
@@ -44,14 +45,6 @@ type Cloud interface {
 func NewCloud(cfg CloudConfig, metricsRegisterer prometheus.Registerer) (Cloud, error) {
 metadataSess := session.Must(session.NewSession(aws.NewConfig()))
 metadata := services.NewEC2Metadata(metadataSess)
-if len(cfg.Region) == 0 {
-region, err := metadata.Region()
-if err != nil {
-return nil, errors.Wrap(err, "failed to introspect region from EC2Metadata, specify --aws-region instead if EC2Metadata is unavailable")
-}
-cfg.Region = region
-}
-
 if len(cfg.VpcID) == 0 {
 vpcId, err := metadata.VpcID()
 if err != nil {
@@ -60,6 +53,22 @@ func NewCloud(cfg CloudConfig, metricsRegisterer prometheus.Registerer) (Cloud,
 cfg.VpcID = vpcId
 }
 
+if len(cfg.Region) == 0 {
+region := os.Getenv("AWS_DEFAULT_REGION")
+if region == "" {
+region = os.Getenv("AWS_REGION")
+}
+
+if region == ""{
+err := (error)(nil)
+region, err = metadata.Region()
+if err != nil {
+return nil, errors.Wrap(err, "failed to introspect region from EC2Metadata, specify --aws-region instead if EC2Metadata is unavailable")
+}
+}
+cfg.Region = region
+}
+
 awsCFG := aws.NewConfig().WithRegion(cfg.Region).WithSTSRegionalEndpoint(endpoints.RegionalSTSEndpoint).WithMaxRetries(cfg.MaxRetries)
 sess := session.Must(session.NewSession(awsCFG))
 injectUserAgent(&sess.Handlers)