In AWS account I created VPC1 using option “create vpc and more” so it creates the entire package with subnets route tables etc automatically. I used default 10.0.0.0/16 cidr block. I created simple RDS Postgres instance and attached security group that allowed all traffic both ways.
I can connect to the database with no problem.
Then I did the same for VPC2 but used non-overlapping cidr of 10.1.0.0/16 and created postgres RDS with security group that allows all traffic both ways. However, the connection times out when I want to access it.
Just to check, I created yet another VPC3 this time again with cidr 10.0.0.0/16 while VPC1 was still in place with its RDS postgres running. On VPC3 I created a postgres RDS with security group that allows all traffic both ways. I can connect to the database.
I repeated this scenario many times deleting and creating VPCs and RDS database instances back and forth so I do not think that there is a place for copy-pasting credentials wrong etc. Every time I make sure that the RDS instance has “publicly available” set to “yes”.
How is that possible? Am I not allowed to use 10.1.0.0 as my cidr for VPC2? How should I proceed?
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Answers
Thank You for all the contributions! After an investigation it turned out that I was creating the vpc with default settings meaning that I had 2 public and 2 private subnets created. When I was creating and RDS instance subsequently I leaft automatic creation of subnet group leading to it including private subnets too. As a result the RDS was landing in the private subnet that is why I could not access it. For anyone having similar issue and reading this post in the future I suggest doing following: before creating RDS instance, manually create a subunet group in RDS menu (on the left panel there is a dedicated place where You can do it). In there create a subnet that consists only of public subnets. Only then proceed to creating the RDS instance and do not leave automatic subnet-group creation but choose the existing one that You just created.
I know this is not following best practices as I learned that typically databases should be in private subnets but this is another topic.
I consider my problem solved. Thank You to everyone that contributed to help me solve the issue and I hope this can be helpful for someone in the future.
To reproduce your situation, I did the following:
10.1.0.0/16:The subnets are:
0.0.0.0/0(instead of the default "My IP")So, it would appear that the problem is with your particular configuration of the Amazon RDS database.