DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Please enter at least three characters to search
Refcards Trend Reports
Events Video Library
Refcards
Trend Reports

Events

View Events Video Library

Zones

Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks

Modernize your data layer. Learn how to design cloud-native database architectures to meet the evolving demands of AI and GenAI workkloads.

Secure your stack and shape the future! Help dev teams across the globe navigate their software supply chain security challenges.

Releasing software shouldn't be stressful or risky. Learn how to leverage progressive delivery techniques to ensure safer deployments.

Avoid machine learning mistakes and boost model performance! Discover key ML patterns, anti-patterns, data strategies, and more.

Related

  • A Guide to Microservices Deployment: Elastic Beanstalk vs Manual Setup
  • Harnessing the Power of AWS Aurora for Scalable and Reliable Databases
  • 7 Invaluable Advantages of Using Amazon RDS
  • Scaling AWS RDS Databases

Trending

  • Measuring the Impact of AI on Software Engineering Productivity
  • Beyond Microservices: The Emerging Post-Monolith Architecture for 2025
  • The Cypress Edge: Next-Level Testing Strategies for React Developers
  • AI-Assisted Coding for iOS Development: How Tools like CursorAI Are Redefining the Developer Workflow
  1. DZone
  2. Software Design and Architecture
  3. Cloud Architecture
  4. AWS Auto Scaling With Hazelcast

AWS Auto Scaling With Hazelcast

In this blog post, I explain how to set up a Hazelcast cluster using the AWS EC2 Auto Scaling mechanism.

By 
Rafał Leszko user avatar
Rafał Leszko
·
Jul. 06, 20 · Tutorial
Likes (1)
Comment
Save
Tweet
Share
5.5K Views

Join the DZone community and get the full member experience.

Join For Free

In this blog post, I explain how to set up a Hazelcast cluster using the AWS EC2 Auto Scaling mechanism. I also give a step-by-step example and justify why other, more trivial solutions may fail.

Introduction

AWS offers an Auto Scaling feature, which allows to dynamically provision EC2 instances depending on specific metrics (CPU, network traffic, etc.). This feature perfectly fits the needs of a Hazelcast cluster.

Hazelcast Requirements

Notice that Hazelcast has specific requirements:

  • the number of instances must change by 1 at the time
  • when an instance is launched or terminated, the cluster must be in the safe state

Otherwise, there is a risk of a data loss or an impact on the performance.

Recommended Solution

The recommended solution is to use Auto Scaling Lifecycle Hooks with Amazon SQS and a custom Lifecycle Hook Listener script. Note however that, if your cluster is small and predictable, then you can try an alternative solution mentioned in the conclusion.

AWS Auto Scaling Architecture

We are going to build the following AWS Auto Scaling architecture.

A look at the AWS auto-scaling architecture.

Setting it up requires the following steps:

  • Create AWS SQS queue
  • Create Amazon Machine Image which includes Hazelcast and Lifecycle Hook Listener script
  • Create Auto Scaling Launch Configuration
  • Create Auto Scaling Group
  • Create Lifecycle Hooks

Let’s see how to set it up.

Step-by-Step Guide

Create Amazon SQS (Simple Queue Service)

As the first step, you need to create an SQS queue that will be used for Autoscaling Group Lifecycle Hook events. Assuming you already executed aws configure and set your default region to eu-central-1, you can execute the following command.

aws sqs create-queue --queue-name=autoscaling-queue

You can check that the queue was created successfully at https://eu-central-1.console.aws.amazon.com/sqs.

Create AMI (Amazon Machine Image) With Hazelcast

As the next step, we need to create an AWS image that will be used for the Autoscaling group.

  1. Launch a new EC2 Instance “Ubuntu Server”
  2. SSH into the launched instance
  3. Install Hazelcast and related libraries
    YAML
     




    x


     
    1
    sudo apt update && sudo apt install -y default-jre unzip 
    2
    sudo chmod a+wr /opt && && mkdir /opt/hazelcast && cd /opt/hazelcast
    3
    wget https://download.hazelcast.com/download.jsp?version=hazelcast-4.0.1 -O hazelcast.zip
    4
    unzip hazelcast.zip && rm -f hazelcast.zip
    5
    wget https://raw.githubusercontent.com/hazelcast/hazelcast-code-samples/master/hazelcast-integration/aws-autoscaling/hazelcast.yaml


  4. Update Hazelcast configuration /opt/hazelcast/hazlecast.yaml with YOUR_AWS_ACCESS_KEY and YOUR_AWS_SECRET_KEY (alternatively you can assign the needed IAM Role to the EC2 Instance)
  5. Download lifecycle_hook_listener.sh
    YAML
     




    xxxxxxxxxx
    1


     
    1
    sudo apt install -y jq
    2
    wget https://raw.githubusercontent.com/hazelcast/hazelcast-code-samples/master/hazelcast-integration/aws-autoscaling/lifecycle_hook_listener.sh -O /opt/lifecycle_hook_listener.sh 
    3
    chmod +x /opt/lifecycle_hook_listener.sh


  6. Install and configure AWS CLI
    sudo apt install -y awscli aws configure
  7. Create AWS Image from the running EC2 Instance

You can check that the image was successfully created at https://eu-central-1.console.aws.amazon.com/ec2/v2/home?region=eu-central-1#Images.

Create Auto Scaling Launch Configuration

Before you create Auto Scaling Group, you need to prepare the configuration of how you want to start EC2 Instance. Proceed with the following steps:

  1. Open AWS Auto Scaling Launch Configuration console: https://eu-central-1.console.aws.amazon.com/ec2/autoscaling/home?region=eu-central-1#LaunchConfigurations
  2. Click on “Create Launch configuration”, select “My AMI”, and choose the created image
  3. In the “Create Launch Configuration” step, in the “User Data” field, add the following script
    YAML
     




    xxxxxxxxxx
    1


     
    1
    #!/bin/bash
    2
    export JAVA_OPTS='-Dhazelcast.config=/opt/hazelcast/hazelcast.yaml'
    3
    /opt/hazelcast/bin/start.sh &
    4
    /opt/lifecycle_hook_listener.sh <sqs-name>


  4. Don’t forget to set up the security group which allows traffic to the Hazelcast member (open port 5701)
  5. Click on “Create launch configuration”

You should see that the Auto Scaling launch configuration has been created.

Create Auto Scaling Group

Finally, you can create an Auto Scaling Group with the following steps.

  1. Open AWS Auto Scaling Group console: https://eu-central-1.console.aws.amazon.com/ec2/autoscaling/home?region=eu-central-1#AutoScalingGroups
  2. Click “Create Auto Scaling group”, select the created launch configuration, and click “Next Step”
  3. Enter “Group Name”, “Network”, and “Subnet” and click on “Next: Configure scaling policies”
  4. Configure scaling policies:
    • Select “Use scaling policies to adjust the capacity of this group”
    • Choose the max and min number of instances
    • Select “Scale the Auto Scaling group using a step or simple scaling policies”
    • Choose (or create) alarms: for “Increase Group Size” and “Decrease Group Size”
    • Specify to always Add and Remove 1 instance
  5. Click “Review” and “Create Auto Scaling group”

The Auto Scaling group should be visible in the AWS console.

Create Lifecycle Hooks

As the last step, we need to create Lifecycle Hooks. Otherwise, Hazelcast members wouldn’t wait before migrating its data, so we could experience data loss.

  1. Create IAM Role that is allowed to publish to SQS (for details, refer to AWS Lifecycle Hooks, Receive Notification Using Amazon SQS)
  2. Check SQS ARN in SQS console: https://console.aws.amazon.com/sqs/home
  3. Create Instance Launching Hook
    Java
     




    xxxxxxxxxx
    1


     
    1
    aws autoscaling put-lifecycle-hook --lifecycle-hook-name <launching-lifecycle-hook-name> --auto-scaling-group-name <autoscaling-group-name> --lifecycle-transition autoscaling:EC2_INSTANCE_LAUNCHING --notification-target-arn <queue-arn> --role-arn <role-arn> --default-result CONTINUE


  4. Create Instance Terminating Hook
    Java
     




    xxxxxxxxxx
    1


     
    1
    aws autoscaling put-lifecycle-hook --lifecycle-hook-name <terminating-lifecycle-hook-name> --auto-scaling-group-name <autoscaling-group-name> --lifecycle-transition autoscaling:EC2_INSTANCE_TERMINATING --notification-target-arn <queue-arn> --role-arn <role-arn> --default-result ABANDON


The lifecycle hooks should be visible in the AWS console

Lifecycle Hook Listener Script

The lifecycle_hook_listener.sh the script takes one argument as a parameter (AWS SQS name) and performs operations that can be expressed in the following pseudocode.

Java
 




xxxxxxxxxx
1


 
1
while true:    message = receive_message_from(queue_name)    instance_ip = extract_instance_ip_from(message)    while not is_cluster_safe(instance_ip):        sleep 5    send_continue_message



You can find a sample lifecycle_hook_listener.sh script in Hazelcast Code Samples.

Understanding Auto Scaling

To better understand how the configured Auto Scaling Group works, let’s examine a simple use case. You can follow the flow of operations that happens when AWS scales down the number of Hazelcast instances.

Phase 1: Trigger Auto Scaling

  • AWS Auto Scaling Group receives an alarm that the specified metric is exceeded (e.g., the average CPU usage is too low)
  • AWS chooses one of the existing instances and changes its state from InService into Terminating: Wait
    • Terminating:Wait means that if there is no CONTINUE signal after TIMEOUT (1h by default), the instance is changed back to InService
    • Terminating:Wait implies that there are no new Auto Scaling operations until the CONTINUE signal
    • Terminating:Wait doesn’t mean that the instance stops; it’s still running
  • Lifecycle Hook “Instance Terminate” sends a notification message to AWS SQS

Phase 2: Wait for Cluster Safe

  • Any of the running lifecycle_hook_listener.sh scripts receive the message
  • The lifecycle_hook_listener.sh script waits until the Hazelcast cluster is safe (by periodically health checking the Hazelcast instance)
  • When the cluster is safe, lifecycle_hook_listener.sh sends the CONTINUE signal to the AWS Autoscaling Group

Phase 3: Terminate EC2 Instance

  • AWS changes the state of the EC2 Instance from Terminating:Wait into Terminating:Proceed
  • The EC2 Instance is terminated
  • AWS Autoscaling Group starts to receive new alarms about increasing/decreasing the number of instances

Conclusion

The AWS Auto Scaling solution presented in this post is complete and independent of the number of Hazelcast members and the amount of data stored. Nevertheless, there are also alternative approaches. They are simpler but may fail under certain conditions. That is why you should use them with caution.

Cooldown Period

Cooldown Period is a statically defined time interval that AWS Auto Scaling Group waits before the next Auto Scaling operation may take place. If your cluster is small and predictable, then you can use it instead of Lifecycle Hooks.

Setting Up

  • Set Scaling Policy to Step scaling and increase/decrease always by adding/removing 1 instance
  • Set Cooldown Period to a reasonable value (which depends on your cluster and data size)

Drawbacks

  • If your cluster contains a significant amount of data, it may be impossible to define one static cooldown period
  • Even if your cluster comes back to the safe state quicker than the cooldown period, the next operation needs to wait

Graceful Shutdown

A solution that may sound good and simple (but is not recommended) is to use Hazelcast Graceful Shutdown as a hook on the EC2 Instance Termination.

Setting Up

Without any autoscaling-specific features, you could adapt the EC2 Instance to wait for the Hazelcast member to shut down before terminating the instance.

Drawbacks

Such a solution may work correctly, however is not recommended for the following reasons:

  • AWS Auto Scaling documentation does not specify the instance termination process, so you can’t rely on anything
  • Some sources (here) specify that it’s possible to gracefully shut down the processes, however, after 20 seconds AWS can kill them anyway
  • The Amazon’s recommended way to deal with graceful shutdowns is to use Lifecycle Hooks
AWS Scaling (geometry) Hazelcast

Published at DZone with permission of Rafał Leszko. See the original article here.

Opinions expressed by DZone contributors are their own.

Related

  • A Guide to Microservices Deployment: Elastic Beanstalk vs Manual Setup
  • Harnessing the Power of AWS Aurora for Scalable and Reliable Databases
  • 7 Invaluable Advantages of Using Amazon RDS
  • Scaling AWS RDS Databases

Partner Resources

×

Comments
Oops! Something Went Wrong

The likes didn't load as expected. Please refresh the page and try again.

ABOUT US

  • About DZone
  • Support and feedback
  • Community research
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Core Program
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 3343 Perimeter Hill Drive
  • Suite 100
  • Nashville, TN 37211
  • support@dzone.com

Let's be friends:

Likes
There are no likes...yet! 👀
Be the first to like this post!
It looks like you're not logged in.
Sign in to see who liked this post!