Get IAM Credential from Metadata API, Fix #10

as.go

@@ -6,24 +6,21 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/awserr"
-	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/autoscaling"
 )
 
-
-func getAutoscalingGroup(instanceId string, region string) (*string, error) {
-	session := session.New(&aws.Config{Region: &region})
+func getAutoscalingGroup(instanceId string) (*string, error) {
 	svc := autoscaling.New(session)
 
 	params := &autoscaling.DescribeAutoScalingInstancesInput{
 		InstanceIds: []*string{&instanceId},
-		MaxRecords: aws.Int64(1),
+		MaxRecords:  aws.Int64(1),
 	}
 
 	resp, err := svc.DescribeAutoScalingInstances(params)
 	if err != nil {
 		if awsErr, ok := err.(awserr.Error); ok {
-			return nil, fmt.Errorf("[%s] %s", awsErr.Code, awsErr.Message)
+			return nil, fmt.Errorf("[%s] %s", awsErr.Code(), awsErr.Message())
 		} else if err != nil {
 			return nil, err
 		}
@@ -34,4 +31,4 @@ func getAutoscalingGroup(instanceId string, region string) (*string, error) {
 	}
 
 	return resp.AutoScalingInstances[0].AutoScalingGroupName, nil
-}
+}

cw.go

@@ -6,7 +6,6 @@ import (
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/aws/aws-sdk-go/aws/awsutil"
-	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/cloudwatch"
 	"io/ioutil"
 	"log"
@@ -71,9 +70,8 @@ func addMetric(name, unit string, value float64, dimensions []*cloudwatch.Dimens
 	return metricData, nil
 }
 
-func putMetric(metricdata []*cloudwatch.MetricDatum, namespace, region string) error {
+func putMetric(metricdata []*cloudwatch.MetricDatum, namespace string) error {
 
-	session := session.New(&aws.Config{Region: &region})
 	svc := cloudwatch.New(session)
 
 	metric_input := &cloudwatch.PutMetricDataInput{
@@ -84,7 +82,7 @@ func putMetric(metricdata []*cloudwatch.MetricDatum, namespace, region string) e
 	resp, err := svc.PutMetricData(metric_input)
 	if err != nil {
 		if awsErr, ok := err.(awserr.Error); ok {
-			return fmt.Errorf("[%s] %s", awsErr.Code, awsErr.Message)
+			return fmt.Errorf("[%s] %s", awsErr.Code(), awsErr.Message())
 		} else if err != nil {
 			return err
 		}

go-aws-mon.go

@@ -2,13 +2,22 @@ package main
 
 import (
 	"flag"
-	"github.com/aws/aws-sdk-go/aws"
-	"github.com/aws/aws-sdk-go/service/cloudwatch"
 	"log"
 	"os"
 	"strings"
+	"net/http"
+	"fmt"
+	"io/ioutil"
+	"encoding/json"
+
+	"github.com/aws/aws-sdk-go/aws"
+	aws_session "github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/cloudwatch"
+	"github.com/aws/aws-sdk-go/aws/credentials"
 )
 
+var session *aws_session.Session
+
 func main() {
 	isAggregated := flag.Bool("aggregated", false, "Adds aggregated metrics for instance type, AMI ID, and overall for the region")
 	isAutoScaling := flag.Bool("auto-scaling", false, "Adds aggregated metrics for the Auto Scaling group")
@@ -34,6 +43,18 @@ func main() {
 		os.Exit(1)
 	}
 
+	credential, err := getIamCredential()
+
+	if err != nil {
+		log.Fatal("Can't get IAM Credential: ", err)
+		os.Exit(1)
+	}
+
+	session = aws_session.New(&aws.Config{
+		Region: aws.String(metadata["region"]),
+		Credentials: credentials.NewStaticCredentials(credential["AccessKeyId"], credential["SecretAccessKey"], credential["Token"]),
+	})
+
 	memUtil, memUsed, memAvail, swapUtil, swapUsed, err := memoryUsage()
 
 	var metricData []*cloudwatch.MetricDatum
@@ -44,7 +65,7 @@ func main() {
 	}
 
 	if *isAutoScaling {
-		if as, err := getAutoscalingGroup(metadata["instanceId"], metadata["region"]); as != nil && err == nil {
+		if as, err := getAutoscalingGroup(metadata["instanceId"]); as != nil && err == nil {
 			dims = append(dims, &cloudwatch.Dimension{
 				Name:  aws.String("AutoScalingGroupName"),
 				Value: as,
@@ -122,8 +143,39 @@ func main() {
 		}
 	}
 
-	err = putMetric(metricData, *ns, metadata["region"])
+	err = putMetric(metricData, *ns)
+	if err != nil {
+		log.Fatal("Can't put CloudWatch Metric: ", err)
+	}
+}
+
+func getIamCredential() (credential map[string]string, err error) {
+	var data map[string]string
+	resp, err := http.Get("http://169.254.169.254/latest/meta-data/iam/security-credentials/")
+	if err != nil {
+		return data, fmt.Errorf("can't reach credentials endpoint - %s", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return data, fmt.Errorf("can't read credentials response body - %s", err)
+	}
+
+	iamRole := string(body)
+
+	resp, err = http.Get("http://169.254.169.254/latest/meta-data/iam/security-credentials/" + iamRole)
 	if err != nil {
-		log.Fatal("Can't put CloudWatch Metric")
+		return data, fmt.Errorf("can't reach credentials content endpoint - %s", err)
 	}
+	defer resp.Body.Close()
+
+	body, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return data, fmt.Errorf("can't read credentials content response body - %s", err)
+	}
+
+	json.Unmarshal(body, &data)
+
+	return data, err
 }