- refactor aws function to a separate file

- add status as a custom type to improve code readability

aws.go

@@ -0,0 +1,210 @@
+package flywheel
+
+import (
+	"log"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/autoscaling"
+	"github.com/aws/aws-sdk-go/service/ec2"
+)
+
+// Start all the resources managed by the flywheel.
+func (fw *Flywheel) Start() error {
+	fw.lastStarted = time.Now()
+	log.Print("Startup beginning")
+
+	var err error
+	err = fw.startInstances()
+
+	if err == nil {
+		err = fw.unterminateAutoScaling()
+	}
+	if err == nil {
+		err = fw.startAutoScaling()
+	}
+
+	if err != nil {
+		log.Printf("Error starting: %v", err)
+		return err
+	}
+
+	fw.ready = false
+	fw.stopAt = time.Now().Add(fw.idleTimeout)
+	fw.status = STARTING
+	return nil
+}
+
+// Start EC2 instances
+func (fw *Flywheel) startInstances() error {
+	if len(fw.config.Instances) == 0 {
+		return nil
+	}
+	log.Printf("Starting instances %v", fw.config.Instances)
+	_, err := fw.ec2.StartInstances(
+		&ec2.StartInstancesInput{
+			InstanceIds: fw.config.AwsInstances(),
+		},
+	)
+	return err
+}
+
+// UnterminateAutoScaling - Restore autoscaling group instances
+func (fw *Flywheel) unterminateAutoScaling() error {
+	var err error
+	for groupName, size := range fw.config.AutoScaling.Terminate {
+		log.Printf("Restoring autoscaling group %s", groupName)
+		_, err = fw.autoscaling.UpdateAutoScalingGroup(
+			&autoscaling.UpdateAutoScalingGroupInput{
+				AutoScalingGroupName: &groupName,
+				MaxSize:              &size,
+				MinSize:              &size,
+			},
+		)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Start EC2 instances in a suspended autoscale group
+// @note The autoscale group isn't unsuspended here. It's done by the
+//       healthcheck once all the instances are healthy.
+func (fw *Flywheel) startAutoScaling() error {
+	for _, groupName := range fw.config.AutoScaling.Stop {
+		log.Printf("Starting autoscaling group %s", groupName)
+
+		resp, err := fw.autoscaling.DescribeAutoScalingGroups(
+			&autoscaling.DescribeAutoScalingGroupsInput{
+				AutoScalingGroupNames: []*string{&groupName},
+			},
+		)
+		if err != nil {
+			return err
+		}
+
+		group := resp.AutoScalingGroups[0]
+
+		instanceIds := []*string{}
+		for _, instance := range group.Instances {
+			instanceIds = append(instanceIds, instance.InstanceId)
+		}
+
+		_, err = fw.ec2.StartInstances(
+			&ec2.StartInstancesInput{
+				InstanceIds: instanceIds,
+			},
+		)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Stop all resources managed by the flywheel
+func (fw *Flywheel) Stop() error {
+	fw.lastStopped = time.Now()
+
+	var err error
+	err = fw.stopInstances()
+
+	if err == nil {
+		err = fw.terminateAutoScaling()
+	}
+	if err == nil {
+		err = fw.stopAutoScaling()
+	}
+
+	if err != nil {
+		log.Printf("Error stopping: %v", err)
+		return err
+	}
+
+	fw.ready = false
+	fw.status = STOPPING
+	fw.stopAt = fw.lastStopped
+	return nil
+}
+
+// Stop EC2 instances
+func (fw *Flywheel) stopInstances() error {
+	if len(fw.config.Instances) == 0 {
+		return nil
+	}
+	log.Printf("Stopping instances %v", fw.config.Instances)
+	_, err := fw.ec2.StopInstances(
+		&ec2.StopInstancesInput{
+			InstanceIds: fw.config.AwsInstances(),
+		},
+	)
+	return err
+}
+
+// Suspend ReplaceUnhealthy in an autoscale group and stop the instances.
+func (fw *Flywheel) stopAutoScaling() error {
+	for _, groupName := range fw.config.AutoScaling.Stop {
+		log.Printf("Stopping autoscaling group %s", groupName)
+
+		resp, err := fw.autoscaling.DescribeAutoScalingGroups(
+			&autoscaling.DescribeAutoScalingGroupsInput{
+				AutoScalingGroupNames: []*string{&groupName},
+			},
+		)
+		if err != nil {
+			return err
+		}
+
+		group := resp.AutoScalingGroups[0]
+
+		_, err = fw.autoscaling.SuspendProcesses(
+			&autoscaling.ScalingProcessQuery{
+				AutoScalingGroupName: group.AutoScalingGroupName,
+				ScalingProcesses: []*string{
+					aws.String("ReplaceUnhealthy"),
+				},
+			},
+		)
+		if err != nil {
+			return err
+		}
+
+		instanceIds := []*string{}
+		for _, instance := range group.Instances {
+			instanceIds = append(instanceIds, instance.InstanceId)
+		}
+
+		_, err = fw.ec2.StopInstances(
+			&ec2.StopInstancesInput{
+				InstanceIds: instanceIds,
+			},
+		)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Reduce autoscaling min/max instances to 0, causing the instances to be terminated.
+func (fw *Flywheel) terminateAutoScaling() error {
+	var err error
+	var zero int64
+	for groupName := range fw.config.AutoScaling.Terminate {
+		log.Printf("Terminating autoscaling group %s", groupName)
+		_, err = fw.autoscaling.UpdateAutoScalingGroup(
+			&autoscaling.UpdateAutoScalingGroupInput{
+				AutoScalingGroupName: &groupName,
+				MaxSize:              &zero,
+				MinSize:              &zero,
+			},
+		)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}