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Deploying Spring Boot talking to MySQL on AWS

In a recent post, I listed some very basic information about running a MySQL database on AWS.  In most cases, we don't want a database alone; we want an application that uses that database for CRUD.

I've created a simple Spring Boot application that exposes a REST API to create and manage lists of things.  The list values are all stored in a MySQL database.

When I went to deploy the application on AWS using Elastic Beanstalk, there were some really good, automatic things that happened to make my life easy:

  • AWS can deploy a Spring Boot jar very easily by simply uploading the jar during setup.
  • AWS creates security groups on the fly so I don't have to worry about extra security configuration.
  • AWS automatically generates DNS information and provides me a URL for accessing the application.
As I deployed the application and saw all of these things, I was pretty excited.  It is nice to have a lot of this stuff taken care of for me.

Then, I tried to test my application... and it was time to deal with problems.

For anyone who has ever worked in software development, you know that nothing ever just fully, magically works.  There is some configuration somewhere that has to be done.  For me, here are the things I had to do:

1. Configure the deployment port
Spring boot deploys on port 8080 by default -- this is common/classic spring.  AWS Elastic Beanstalk wants me to deploy on port 5000 because it somehow magically redirects traffic from standard web/HTTP ports to port 5000.  To make this magic work, I had to modify Software under Configuration:

Once there, we have to set the SERVER_PORT environment variable to 5000.  Spring automatically detects this environment variable and updates the server.port property to use this value.  Problem #1 solved.

2. Configure the database password
I am using JdbcTemplate on top of a MysqlDataSource in my application.  The data source is configured to pull the server name, user, and password from standard spring data properties:
  • spring.datasource.url
  • spring.datasource.username
  • spring.datasource.password
I don't mind leaving the url and username in the properties file for deployment (if I was really serious about security, then I WOULD mind), but I certainly don't want a plain text password out there anywhere being used.  Even though I checked in a dummy password into the properties file, that password is incorrect and won't work against the AWS database for my user.  So I also have to set the password somehow.  Using the same configuration options as the port problem, I set the SPRING_DATASOURCE_PASSWORD variable to the appropriate password.  Spring reads this value and automatically maps it to spring.datasource.password.  Problem #2 solved.

3. The application cannot talk to the database because of AWS security
When I created the MySQL database server, AWS put that server into a security group whose configuration said "only allow the IP address of the workstation that created this database server to access the database."  So even though the database was created with 'public' access, that access was still restricted to a single IP address.  The Spring Boot application running in AWS Elastic Beanstalk doesn't have my workstation's IP addresss, so the application could not connect to the database server.

To resolve this problem, I had to configure the security groups in my overall AWS environment.  This meant going to the EC2 management console, viewing Security Groups, and then adding an Inbound Rule to my database server security group that allows the Spring Boot app to connect.  Problem #3 solved.

How to get to EC2 Security Groups:

The new rule.  Notice that the Source is just the group id for my Spring Boot app.

Now, I run a Postman test against an endpoint at the URL given to me by AWS Elastic Beanstalk, and everything looks good!


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