You may have heard of Amazon Aurora, a custom built MySQL and PostgreSQL compatible database born and built in the cloud. You may have also heard of serverless, which allows you to build and run applications and services without thinking about instances. These are two pieces of the growing AWS technology story that we’re really excited to be working on. Last year, at AWS re:Invent we announced a preview of a new capability for Aurora called Aurora Serverless. Today, I’m pleased to announce that Aurora Serverless for Aurora MySQL is generally available. Aurora Serverless is on-demand, auto-scaling, serverless Aurora. You don’t have to think about instances or scaling and you pay only for what you use.

This paradigm is great for applications with unpredictable load or infrequent demand. In production, you can save on costs by adjusting to scale based on actual load, in extremely granular increments – matching your demand curve almost perfectly. In development, you can save on costs by automatically pausing the cluster (scale to zero!) when it’s not in use. I’m excited to show you how this all works so let’s look at how we launch a Serverless Aurora cluster.

Creating an Aurora Serverless Cluster

First, I’ll navigate to the Amazon Relational Database Service (RDS) console and select the Clusters sub-console. From there, I’ll click the Create database button in the top right corner to get to this screen.

From the screen above I select my engine type and click next, for now only Aurora MySQL 5.6 is supported.

Now comes the fun part. I specify my capacity type as Serverless and all of the instance selection and configuration options go away. I only have to give my cluster a name and a master username/password combo and click next.

From here I can select a number of options. I can specify the minimum and maximum number of Aurora Capacity Units (ACU) to be consumed. These are billed per-second, with a 5-minute minimum, and my cluster will autoscale between the specified minimum and maximum number of ACUs. The rules and metrics for autoscaling will be automatically created by Aurora Serverless and will include CPU utilization and number of connections. When Aurora Serverless detects that my cluster needs additional capacity it will grab capacity from a warm pool of resources to meet the need. This new capacity can start serving traffic in seconds because of the separation of the compute layer and storage layer intrinsic to the design of Aurora.

The cluster can even automatically scale down to zero if it isn’t seeing any activity. This is perfect for development databases that might go long periods of time with little or no use. When the cluster is paused I’m only charged for the underlying storage. If I want to manually scale up or down, pre-empting a large spike in traffic, I can easily do that with a single API call.

Finally, I click Create database in the bottom right and wait for my cluster to become available – which happens quite quickly. For now we only support a limited number of cluster parameters with plans to enable more customized options as we iterate on customer feedback.

Now, the console provides a wealth of data, similar to any other RDS database.

From here, I can connect to my cluster like any other MySQL database. I could run a tool like sysbench or mysqlslap to generate some load and trigger a scaling event or I could just wait for the service to scale down and pause.

If I scroll down or select the events subconsole I can see a few different autoscaling events happening including pausing the instance at one point.

The best part about this? When I’m done writing the blog post I don’t need to remember to shut this server down! When I’m ready to use it again I just make a connection request and my cluster starts responding in seconds.

How Aurora Serverless Works

I want to dive a bit deeper into what exactly is happening behind the scenes to enable this functionality. When you provision an Aurora Serverless database the service does a few things:

It creates an Aurora storage volume replicated across multiple AZs.

It creates an endpoint in your VPC for the application to connect to.

It configures a network load balancer (invisible to the customer) behind that endpoint.

It configures multi-tenant request routers to route database traffic to the underlying instances.

It provisions the initial minimum instance capacity.

When the cluster needs to autoscale up or down or resume after a pause, Aurora grabs capacity from a pool of already available nodes and adds them to the request routers. This process takes almost no time and since the storage is shared between nodes Aurora can scale up or down in seconds for most workloads. The service currently has autoscaling thresholds of 1.5 minutes to scale up and 5 minutes to scale down. That means metrics must exceed the limits for 1.5 minutes to trigger a scale up or fall below the limits for 5 minutes to trigger a scale down. The cooldown period between scaling activities is 5 minutes to scale up and 15 minutes to scale down. Before scaling can happen the service has to find a “scaling point” which may take longer than anticipated if you have long-running transcations. Scaling operations are transparent to the connected clients and applications since existing connections and session state are transferred to the new nodes. The only difference with pausing and resuming is a higher latency for the first connection, typically around 25 seconds. You can find more details in the documentation.

Available Now

Aurora Serverless for Aurora MySQL is available now in US East (N. Virginia), US East (Ohio), US West (Oregon), Europe (Ireland), Asia Pacific (Tokyo). If you’re interested in learning more about the Aurora engine there’s a great design paper available. If you’re interested in diving a bit deeper on exactly how Aurora Serverless works then look forward to more detail in future posts!

I personally believe this is one of the really exciting points in the evolution of the database story and I can’t wait to see what customers build with it!

– Randall