AWS: can't connect to RDS database from my machine

Question

The EC2 instance/live web can connect just fine to the RDS database. But when I want to debug the code in my local machine, I can\'t connect to the database and got this error:<

Answer 1

Make sure that your VPC and subnets are wide enought.

The following CIDR configuration works great for two subnets:

• VPC 10.0.0.0/16 10.0.0.0 — 10.0.255.255 (65536 addresses)

• Subnet 1 10.0.0.0/17 10.0.0.0 — 10.0.127.255 (32768 addresses, half)

• Subnet 2 10.0.128.0/17 10.0.128.0 — 10.0.255.255 (32768 addresses, other half)

Adjust it if you need three subnets.

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I wasn't being able to connect to my RDS database. I've manually reviewed any detail and everything was alright. There were no indications of any issues whatsoever and I couldn't find any suitable information in the documentation. My VPC was configured with narrow CIDR: 10.0.0.0/22 and each subnet had a 255 addresses. After I've changed CIDR to 10.0.0.0/16 and split it totally between two subnets my RDS connection started to working. It was a pure luck that I've managed to find a source of the problem, because it doesn't make any sense to me.

Answer 2

In my case, when I upgrade the size. The private address of the rds instance fell into a private subnet of the VPC. You can use the article My instance is in a private subnet, and I can't connect to it from my local computer to find out your db instance address.

However, changing the route table didn't fix my issue. What I did finally solve my problem is to downgrade the size and then upgrade the size back. Once the private address falls back to the public subnet. Everything works like a charm.

Answer 3

I was also not able to connect even from inside an ec2 instance.

After digging AWS RDS options it turns out that ec2 instances are only able to connect to RDS in the same VPC they are in.

When creating an ec2 instance in the same VPC where the RDS was I could access it as expected.

Answer 4

MAKE SURE PUBLIC ACCESSIBILITY IS SET TO YES

This is what I spent the last 3 days trying to solve...

Instructions to change Public Accessibility

Answer 5

Just burned two hours going through the great solutions on this page. Time for the stupid answer!

I redid my Security Groups, VPC's, Routing Tables, Subnets, Gateways... NOPE. I copy-pasted the URL from the AWS Console, which in some cases results in a hidden trailing space. The endpoint is in a <div> element, which the browser gives a \n when copying. Pasting this into the Intellij db connector coerces it to a space.

I only noticed the problem after pasting the URL into a quote string in my source code.

Answer 6

It turns out it is not that hard. Do these steps:

1. Go to EC2 Dashboard
2. Go to Security Groups tab
3. Select and only select the RDS database security group. You'll see the security group detail at the bottom
4. Click Inbound tab
5. Click Edit button
6. Add Type:MYSQL/Aurora;Protocol:TCP;Range:3306;Source:0.0.0.0/0