AWS Elastic Beanstalk

What it is

AWS Elastic Beanstalk deploys and runs web applications for you. You upload your code, and Elastic Beanstalk creates and manages everything it needs: EC2 instances, an Auto Scaling group, a load balancer, health monitoring, and logging. You can still see and adjust every resource it creates; it is a convenience layer over normal AWS services, not a black box.

Elastic Beanstalk supports applications written in Go, Java, .NET, Node.js, PHP, Python, and Ruby, and Docker containers for anything else. It is the usual answer when a question asks to deploy a web application quickly, with the least operational overhead, while keeping the option to control the underlying resources.

Elastic Beanstalk now has two modes. Beanstalk Standard runs applications directly on EC2, as described in this tutorial. Beanstalk Cluster runs applications as containers on Amazon EKS, for faster deployments and scaling when you run many environments.

Concepts

Application: a container for versions, environments, and configurations.
Application version: a labeled copy of deployable code, such as a ZIP or WAR file, stored in Amazon S3.
Environment: the AWS resources running one application version. You might have separate development, test, and production environments for the same application.
Platform: the operating system, language runtime, and web or application server, such as a Python or Node.js platform on Amazon Linux 2023.
Environment type: load-balanced, scalable (an Elastic Load Balancing load balancer and an Auto Scaling group across AZ (Availability Zone)An isolated location within an AWS Region, made up of one or more data centers with their own power, cooling, and networking. The AZs in a Region are linked by fast, low-latency connections, so spreading resources across them protects against the failure of one site.Glossary entry) for production, or single-instance (one instance with an Elastic IP (Internet Protocol)The protocol that addresses and routes packets between networks. Each device has an IP address: IPv4 addresses look like 192.0.2.1, and IPv6 addresses are longer, like 2001:db8::1.Glossary entry address, no load balancer) for development and low traffic.

Environment tiers

A web server environment serves HTTP (Hypertext Transfer Protocol)The protocol that web browsers and APIs use to send requests, such as GET and POST, and receive responses. On its own it is not encrypted; HTTPS adds TLS.Glossary entry requests behind a load balancer.
A worker environment processes background tasks from an Amazon SQS queue. A daemon on each instance reads messages and sends each one as an HTTP POST to your application on the instance; a 200 OK response deletes the message, and failures are retried and eventually go to a DLQ (Dead-letter queue)A queue that receives messages that could not be processed after a set number of attempts, so they stop blocking other messages and can be inspected later. Amazon SQS, Amazon SNS, AWS Lambda, and Amazon EventBridge can send failed messages to one.Glossary entry.
A cron.yaml file in a worker environment schedules periodic tasks.

Putting long-running work, such as video processing or report generation, in a worker environment keeps the web tier responsive. This DecouplingDesigning components so that they do not depend directly on each other being available, for example by passing work through a queue. A slow or failed component then does not stop the others, and each can scale on its own.Glossary entry is a common exam pattern.

Elastic Beanstalk web and worker tiers. Users send HTTP requests to the web server environment, which sends long-running jobs to an SQS queue. In the worker environment, a daemon reads each message and sends it to your app as an HTTP POST. Messages that keep failing go to a dead-letter queue after retries.

Deployment policies

Policy	How it works	Downtime	Cost and speed	Rollback
All at once	Deploys to every instance at the same time	Yes, briefly	Fastest	Redeploy
Rolling	Deploys in batches	No, but capacity drops by one batch	Moderate	Redeploy
Rolling with additional batch	Launches an extra batch first, then rolls	No, full capacity kept	Slower; extra instances briefly	Redeploy
Immutable	Launches a new Auto Scaling group with the new version, then removes the old instances	No	Slowest; doubles capacity briefly	Terminate the new instances
Traffic splitting	Sends a percentage of traffic to new instances for an evaluation period (canary)	No	Slow	Reroute traffic to the old instances
Blue/green deploymentReleasing a new version (green) alongside the running one (blue), then moving traffic to green once it is ready. Rolling back is quick: move the traffic back to blue.Glossary entry	Deploy to a separate environment, then swap environment URLs (a CNAME (Canonical name record)A DNS record that makes one domain name an alias of another, such as www.example.com pointing to example.com. A CNAME cannot be used for the zone apex (example.com itself); Route 53 alias records cover that case.Glossary entry swap)	No	Two full environments	Swap back

Use blue/green when the new version cannot run alongside the old one, or to change to an incompatible platform version. Keep the production database outside the environment, for example in Amazon RDS created separately, so it survives when an environment is replaced or terminated.

Configuration

Configuration files (.config files in an .ebextensions folder in your source bundle) set options, install packages, run commands, and add other AWS resources through AWS CloudFormation.
Saved configurations capture an environment's settings so you can create identical environments.
Managed platform updates apply patch and minor platform updates automatically in a weekly maintenance window, using an immutable update so the application stays in service.

Security, resilience, performance, and cost

Security

Elastic Beanstalk uses a service role to manage resources for you, and an instance profile that gives the instances their permissions, for example to read from S3 or send logs.
Run environments in your VPC, with instances in SubnetA range of IP addresses in a VPC, inside one Availability Zone. A subnet is public when its route table sends internet traffic to an internet gateway, and private when it does not.Glossary entry and the load balancer in public subnets, and use Security groupA stateful virtual firewall for network interfaces, such as an EC2 instance's, whose rules can only allow traffic. Return traffic for allowed connections is allowed automatically, and a rule can refer to another security group instead of IP addresses.Glossary entry to limit access.
Store secrets in AWS Secrets Manager or Systems Manager Parameter Store rather than in the source bundle.
Turn on managed platform updates so the operating system and runtime get security patches.

Resilience

A load-balanced environment spreads instances across Availability Zones and replaces unhealthy ones through its Auto Scaling group.
Choose a deployment policy without downtime, such as rolling with additional batch, immutable, or blue/green, for production.
Keep the database and any state outside the environment.

Performance

Configure the Auto Scaling group's triggers, such as CPU or network, and the instance type, through the environment's capacity settings.
Use a worker environment for long tasks so they don't slow down web requests.

Cost

Elastic Beanstalk has no additional charge; you pay for the EC2 instances, load balancer, storage, and other resources it creates.
Use single-instance environments for development, and scale production environments with demand.

Monitoring

Enhanced health reporting uses an agent on each instance to report application and operating system health every 10 seconds, with color-coded status and causes in the console. You can publish detailed health metrics to Amazon CloudWatch for a fee.
Instance logs can stream to CloudWatch Logs, with a retention period you choose.
Environment events record deployments, configuration changes, and health transitions; AWS CloudTrail records API (Application programming interface)A defined way for one program to ask another for data or actions, such as a set of HTTPS requests and responses. Every AWS service is controlled through its API, which the console, the CLI, and the SDKs call for you.Glossary entry calls.

Elastic Beanstalk or another service?

If the requirement is	Choose
Deploy a web application with the least effort, keeping control of resources	AWS Elastic Beanstalk
Full control of servers and every setting	Amazon EC2 with Auto Scaling and a load balancer
Run containers with an orchestrator you configure	Amazon ECS or Amazon EKS
Event-driven architectureA design in which services react to events that other services emit, such as an order placed or a file uploaded, instead of calling each other directly. Amazon EventBridge, Amazon SNS, Amazon SQS, and AWS Lambda are common building blocks.Glossary entry code with no servers	AWS Lambda
Define any IaC (Infrastructure as code)Defining infrastructure, such as networks, servers, and permissions, in text files that are versioned and deployed automatically, instead of setting it up by hand. AWS CloudFormation and the AWS CDK are AWS tools for it.Glossary entry	AWS CloudFormation (Elastic Beanstalk uses it under the hood)

Reverse mindmap: when the question points here

Is it Elastic Beanstalk?

Yes, when the question says
- Deploy a web app quickly, least operational overhead leads to Elastic Beanstalk
- Developers upload code, AWS handles capacity and scaling leads to Elastic Beanstalk
- Background tasks from a queue leads to Worker environment with SQS
- Scheduled jobs for the worker tier leads to cron.yaml periodic tasks
Choose the deployment
- Fastest deploy, downtime acceptable leads to All at once
- No downtime, full capacity kept leads to Rolling with additional batch
- Safest rollback, new instances only leads to Immutable
- Test the new version on some traffic leads to Traffic splitting
- Switch instantly and swap back if needed leads to Blue/green with URL swap
Run it well
- Database must survive environment replacement leads to RDS outside the environment
- Install packages or set options at deploy leads to .ebextensions configuration files
- Keep the platform patched automatically leads to Managed platform updates
No, when the question says
- Full control over every server setting leads to EC2 with Auto Scaling
- Container orchestration you manage leads to ECS or EKS

Key takeaways

Elastic Beanstalk deploys web applications onto EC2, Auto Scaling, and a load balancer for you, at no extra charge.
Web server environments serve HTTP; worker environments process SQS messages.
Deployment policies trade speed for safety: all at once, rolling, rolling with additional batch, immutable, traffic splitting, and blue/green by URL swap.
Keep databases outside the environment; customize with .ebextensions; let managed platform updates patch it.
Enhanced health reporting and CloudWatch Logs streaming give visibility into the environment.