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How To Use AWS EFS for a Load Balanced Environment

The RESTful Engine uses local storage to store the cache and requests. This is fine for a single instance, but if you want to use a load balanced system you need to setup some form of shared storage that all instances can access, so that the app can behave in a stateless manner.

This article outlines the steps you need to take to setup your AWS load balanced system with AWS EFS. This will allow you to use a load balanced system without the need to implement your own external storage plugin.

Steps​

Note: all these steps are summarized from the AWS documentation here

Step 1: Create your Amazon EFS file system​

  1. Sign in to the AWS Management Console and open the Amazon EFS console at https://console.aws.amazon.com/efs/.

  2. Choose Create file system to open the Create file system dialog box. Enter a name for your File System and click create:

Step 2: Create your EC2 resources and launch your EC2 instance​

  1. For this step, you can just follow the instructions here

  2. Once you've created you EC2 instances, follow the instructions here to setup the Java RESTful Engine.

  3. Finally, follow the steps here tp install the Amazon EFS client on your VMs.

Step 3: Create a Load Balancer​

Next, we need to setup a load balancer with the VMs that we want. This will allow your application to make use of the EFS. To do this, follow the instructions here

Step 3: Mounting on Amazon EC2 Linux instances using the EFS mount helper​

In this step, we will mount the EFS we created to the App_Data directory in our Java RESTful install.

  1. Aquire the "File system ID" for the EFS instance we created

    • To do this, navigate to the EFS Console and find the EFS we created. There you will find the File system ID:

  2. Next, in the terminal of your VM navigate to the webapps folder for our Java RESTful Install (it should be in the /tomcat directory)

  3. Make sure youre in the webapps directory, then run the following command:

sudo mount -t efs {EFS-ID} App_Data/

Where {EFS-ID} is the ID we aquiured earlier

Make sure you do step 3 an all VMs in your load balancer.

And thats it! Your loadbalancer is now using a shared file system, and all node in your load balancer will have access to the same App_Data folder.