Initial Commit

elb.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"flag"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/ec2metadata"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/elb"
+)
+
+var loadBalancerName = flag.String("name", "", "the access point name of the load balancer")
+var registerOperation = flag.Bool("register", false, "register this instance in the load balancer")
+var deregisterOperation = flag.Bool("deregister", false, "deregister this instance in the load balancer")
+
+func register(instanceID string, svc *elb.ELB) {
+	params := &elb.RegisterInstancesWithLoadBalancerInput{
+		Instances: []*elb.Instance{ // Required
+			{ // Required
+				InstanceId: aws.String(instanceID),
+			},
+			// More values...
+		},
+		LoadBalancerName: aws.String(*loadBalancerName), // Required
+	}
+	_, err := svc.RegisterInstancesWithLoadBalancer(params)
+
+	if err != nil {
+		// Print the error, cast err to awserr.Error to get the Code and
+		// Message from an error.
+		fmt.Println(err.Error())
+		return
+	}
+
+	fmt.Println("Instance", instanceID, "registered.")
+}
+
+func deregister(instanceID string, svc *elb.ELB) {
+	params := &elb.DeregisterInstancesFromLoadBalancerInput{
+		Instances: []*elb.Instance{ // Required
+			{ // Required
+				InstanceId: aws.String(instanceID),
+			},
+			// More values...
+		},
+		LoadBalancerName: aws.String(*loadBalancerName), // Required
+	}
+	_, err := svc.DeregisterInstancesFromLoadBalancer(params)
+
+	if err != nil {
+		// Print the error, cast err to awserr.Error to get the Code and
+		// Message from an error.
+		fmt.Println(err.Error())
+		return
+	}
+
+	fmt.Println("Instance", instanceID, "deregistered.")
+}
+
+func main() {
+	flag.Parse()
+
+	session := session.New(&aws.Config{Region: aws.String("us-east-1")})
+	svc := elb.New(session)
+	metadata := ec2metadata.New(session)
+
+	instanceID, _ := metadata.GetMetadata("instance-id")
+
+	if instanceID == "unknown" {
+		fmt.Printf("Unable to determine AWS instance ID.\n")
+		os.Exit(1)
+	}
+
+	if *registerOperation == true && *deregisterOperation == false {
+		register(instanceID, svc)
+		os.Exit(0)
+	}
+
+	if *deregisterOperation == true && *registerOperation == false {
+		deregister(instanceID, svc)
+		os.Exit(0)
+	}
+
+	fmt.Printf("Unable to parse command flags.\n")
+	os.Exit(1)
+}