feat(plugin): Support extracting AWS instance name (#21)

plugin/plugin.go

@@ -21,10 +21,16 @@ import (
 	"google.golang.org/protobuf/types/known/structpb"
 )
 
-// rotationWaitTimeout controls the time we wait for credential rotation to
-// succeed. This is important to ensure that rotated credentials can be used
-// right away.
-const rotationWaitTimeout = time.Second * 30
+const (
+	// rotationWaitTimeout controls the time we wait for credential rotation to
+	// succeed. This is important to ensure that rotated credentials can be used
+	// right away.
+	rotationWaitTimeout = time.Second * 30
+
+	// instanceNameTagKey denotes the special AWS tag key that contains an EC2
+	// instance's name. This field is to be matched literally.
+	instanceNameTagKey = "Name"
+)
 
 // AwsPlugin implements the HostPluginServiceServer interface for the
 // AWS plugin.
@@ -596,6 +602,14 @@ func awsInstanceToHost(instance *ec2.Instance) (*pb.ListHostsResponseHost, error
 	// External ID is the instance ID.
 	result.ExternalId = aws.StringValue(instance.InstanceId)
 
+	// External Name is the AWS "Name" tag, if it exists.
+	for _, t := range instance.Tags {
+		if aws.StringValue(t.Key) == instanceNameTagKey {
+			result.ExternalName = aws.StringValue(t.Value)
+			break
+		}
+	}
+
 	// First IP address/dns name are always the private fields if they
 	// are populated
 	if aws.StringValue(instance.PrivateIpAddress) != "" {

plugin/plugin_test.go

@@ -1769,6 +1769,43 @@ func TestAwsInstanceToHost(t *testing.T) {
 				DnsNames:    []string{"test.example.internal", "test.example.com"},
 			},
 		},
+		{
+			name: "good, single IP w/public addr and external name",
+			instance: &ec2.Instance{
+				InstanceId:       aws.String("foobar"),
+				PrivateIpAddress: aws.String("10.0.0.1"),
+				PrivateDnsName:   aws.String("test.example.internal"),
+				PublicIpAddress:  aws.String("1.1.1.1"),
+				PublicDnsName:    aws.String("test.example.com"),
+				Tags: []*ec2.Tag{
+					{Key: aws.String("Name"), Value: aws.String("test-instance-actual-name")}, // The tag name is "Name", not "name".
+					{Key: aws.String("name"), Value: aws.String("test-instance-fake-name")},
+					{Key: aws.String("contains-Name"), Value: aws.String("test-instance-contains-name")},
+				},
+				NetworkInterfaces: []*ec2.InstanceNetworkInterface{
+					{
+						PrivateIpAddress: aws.String("10.0.0.1"),
+						PrivateDnsName:   aws.String("test.example.internal"),
+						PrivateIpAddresses: []*ec2.InstancePrivateIpAddress{
+							{
+								Association: &ec2.InstanceNetworkInterfaceAssociation{
+									PublicIp:      aws.String("1.1.1.1"),
+									PublicDnsName: aws.String("test.example.com"),
+								},
+								PrivateIpAddress: aws.String("10.0.0.1"),
+								PrivateDnsName:   aws.String("test.example.internal"),
+							},
+						},
+					},
+				},
+			},
+			expected: &pb.ListHostsResponseHost{
+				ExternalId:   "foobar",
+				ExternalName: "test-instance-actual-name",
+				IpAddresses:  []string{"10.0.0.1", "1.1.1.1"},
+				DnsNames:     []string{"test.example.internal", "test.example.com"},
+			},
+		},
 	}
 
 	for _, tc := range cases {