Merge pull request #1 from tenjin/rotate-instance

Single Instance Rotator

Dockerfile

@@ -2,8 +2,9 @@ FROM golang:alpine as buildenv
 WORKDIR /go/src/github.com/tenjin/rotate-eks-asg
 COPY . .
 RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o /rotate-eks-asg ./cmd/rotate-eks-asg
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o /rotate-eks-instance ./cmd/rotate-eks-instance
 
-# Extract `rotate-eks-asg` and ship with rest of tooling:
+# Extract and ship with rest of tooling:
 
 FROM python:3-alpine
 RUN apk add --no-cache git
@@ -24,6 +25,7 @@ RUN chmod +x \
     /usr/local/bin/aws-iam-authenticator
 
 COPY --from=buildenv /rotate-eks-asg /usr/local/bin/
+COPY --from=buildenv /rotate-eks-instance /usr/local/bin/
 ADD ./script ./script
 
 ENTRYPOINT ["./script/entrypoint.sh"]

Makefile

@@ -7,3 +7,4 @@ deps:
 	GO111MODULE=on go mod vendor
 install:
 	GO111MODULE=on go install -mod=vendor ./cmd/rotate-eks-asg
+	GO111MODULE=on go install -mod=vendor ./cmd/rotate-eks-instance

cmd/rotate-eks-asg/main.go

@@ -11,10 +11,10 @@ import (
 )
 
 var (
-	groups  = kingpin.Arg("groups", "EKS Auto Scaling Groups to rotate").Required().Strings()
+	groups = kingpin.Arg("groups", "EKS Auto Scaling Groups to rotate").Required().Strings()
 )
 
-func init() { // TODO
+func init() {
 	_ = os.Setenv("AWS_SDK_LOAD_CONFIG", "true")
 }
 

cmd/rotate-eks-instance/main.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/complex64/go-utils/pkg/ctxutil"
+	"gopkg.in/alecthomas/kingpin.v2"
+
+	"github.com/tenjin/rotate-eks-asg/internal/pkg/rotator"
+)
+
+var (
+	name = kingpin.Arg("name", "Internal DNS of EKS instance to rotate").Required().String()
+)
+
+func init() {
+	_ = os.Setenv("AWS_SDK_LOAD_CONFIG", "true")
+}
+
+func main() {
+	kingpin.Parse()
+	ctx, cancel := ctxutil.ContextWithCancelSignals(os.Kill, os.Interrupt)
+	defer cancel()
+	if err := rotator.RotateByInternalDNS(ctx, *name); err != nil {
+		log.Fatal(err)
+	}
+}

internal/pkg/rotator/aws.go

@@ -1,6 +1,7 @@
 package rotator
 
 import (
+	"errors"
 	"fmt"
 	"log"
 
@@ -30,6 +31,54 @@ func DescribeAutoScalingGroup(client *autoscaling.AutoScaling, name string) (*Gr
 	return g, nil
 }
 
+func DescribeInstanceByInternalDNS(
+	ec2Client *ec2.EC2,
+	asgClient *autoscaling.AutoScaling,
+	instanceInternalDNS string,
+) (string, string, error) {
+	input := &ec2.DescribeInstancesInput{
+		Filters: []*ec2.Filter{{
+			Name:   aws.String("network-interface.private-dns-name"),
+			Values: []*string{aws.String(instanceInternalDNS)},
+		}},
+	}
+	var instanceID string
+	err := ec2Client.DescribeInstancesPages(input,
+		func(output *ec2.DescribeInstancesOutput, isLast bool) bool {
+			instanceID = *(output.Reservations[0].Instances[0].InstanceId)
+			return false
+		})
+	if err != nil {
+		return "", "", err
+	}
+	if instanceID == "" {
+		return "", "", errors.New(fmt.Sprintf("%s: No matching instance could be found", instanceInternalDNS))
+	}
+
+	log.Printf("Internal DNS '%s' is instance ID '%s'", instanceInternalDNS, instanceID)
+
+	var groupName string
+	asgInput := &autoscaling.DescribeAutoScalingInstancesInput{
+		InstanceIds: []*string{aws.String(instanceID)},
+	}
+	err = asgClient.DescribeAutoScalingInstancesPages(asgInput,
+		func(output *autoscaling.DescribeAutoScalingInstancesOutput, isLast bool) bool {
+			for _, instance := range output.AutoScalingInstances {
+				groupName = *(instance.AutoScalingGroupName)
+				return false
+			}
+			return true
+		})
+	if err != nil {
+		return "", "", err
+	}
+	if groupName == "" {
+		return "", "", errors.New(fmt.Sprintf("%s: No matching ASG could be found", instanceInternalDNS))
+	}
+
+	return instanceID, groupName, nil
+}
+
 func getAutoScalingGroup(client *autoscaling.AutoScaling, name string) (*autoscaling.Group, error) {
 	in := &autoscaling.DescribeAutoScalingGroupsInput{
 		AutoScalingGroupNames: aws.StringSlice([]string{name}),

internal/pkg/rotator/rotator.go

@@ -2,13 +2,12 @@ package rotator
 
 import (
 	"context"
-	"log"
-
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/autoscaling"
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"k8s.io/client-go/kubernetes"
 	_ "k8s.io/client-go/plugin/pkg/client/auth/exec"
+	"log"
 )
 
 func RotateAll(ctx context.Context, groups []string) error {
@@ -46,6 +45,24 @@ func Rotate(ctx context.Context, groupId string) error {
 	return nil
 }
 
+func RotateByInternalDNS(ctx context.Context, instanceInternalIP string) error {
+	sess, err := session.NewSession()
+	if err != nil {
+		return err
+	}
+	asgClient := autoscaling.New(sess)
+	ec2Client := ec2.New(sess)
+	instanceID, groupID, err := DescribeInstanceByInternalDNS(ec2Client, asgClient, instanceInternalIP)
+	if err != nil {
+		return err
+	}
+	k8s, err := NewKubernetesClient()
+	if err != nil {
+		return err
+	}
+	return RotateInstance(ctx, k8s, asgClient, ec2Client, groupID, instanceID)
+}
+
 func RotateInstance(
 	ctx context.Context,
 	k8s *kubernetes.Clientset,