Merge pull request #65 from gruntwork-io/get-syslog

Add methods to fetch syslog for EC2 instances

aws/ec2-syslog.go

@@ -0,0 +1,78 @@
+package aws
+
+import (
+	"log"
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/gruntwork-io/terratest/util"
+	"fmt"
+	"time"
+	"encoding/base64"
+)
+
+// Get the syslog for the Instance with the given ID in the given region. This should be available ~1 minute after an
+// Instance boots and is very useful for debugging boot-time issues, such as an error in User Data.
+func GetSyslogForInstance(instanceId string, awsRegion string, logger *log.Logger) (string, error) {
+	description := fmt.Sprintf("Fetching syslog for Instance %s in %s", instanceId, awsRegion)
+	maxRetries := 60
+	timeBetweenRetries := 5 * time.Second
+
+	logger.Printf(description)
+
+	ec2Client, err := CreateEC2Client(awsRegion)
+	if err != nil {
+		return "", err
+	}
+
+	input := ec2.GetConsoleOutputInput {
+		InstanceId: aws.String(instanceId),
+	}
+
+	syslogB64, err := util.DoWithRetry(description, maxRetries, timeBetweenRetries, logger, func() (string, error) {
+		out, err := ec2Client.GetConsoleOutput(&input)
+		if err != nil {
+			return "", err
+		}
+
+		syslog := aws.StringValue(out.Output)
+		if syslog == "" {
+			return "", fmt.Errorf("Syslog is not yet available for instance %s in %s", instanceId, awsRegion)
+		}
+
+		return syslog, nil
+	})
+
+	if err != nil {
+		return "", err
+	}
+
+	syslogBytes, err := base64.StdEncoding.DecodeString(syslogB64)
+	if err != nil {
+		return "", err
+	}
+
+	return string(syslogBytes), nil
+}
+
+// Get the syslog for each of the Instances in the given ASG in the given region. These logs should be available ~1
+// minute after the Instance boots and are very useful for debugging boot-time issues, such as an error in User Data.
+// Returns a map of Instance Id -> Syslog for that Instance.
+func GetSyslogForInstancesInAsg(asgName string, awsRegion string, logger *log.Logger) (map[string]string, error) {
+	logger.Printf("Fetching syslog for each Instance in ASG %s in %s", asgName, awsRegion)
+
+	instanceIds, err := GetEc2InstanceIdsByTag(awsRegion, "aws:autoscaling:groupName", asgName)
+	if err != nil {
+		return nil, err
+	}
+
+	logs := map[string]string{}
+	for _, instanceId := range instanceIds {
+		syslog, err := GetSyslogForInstance(instanceId, awsRegion, logger)
+		if err != nil {
+			return nil, err
+		}
+		logs[instanceId] = syslog
+	}
+
+	return logs, nil
+}