This video is going to be about a solution to an AWS issue that is generally encountered while deleting an AWS security Group with a dependent resource.
This issue is also sometimes found while deleting a default VPC with a security group that has a dependent resource. So, let’ get started.
Here, I have the two security groups, the first one is the default security group while the other is the security group that I have created to loadbalancers. Just to so you the issue, I select the first security group, go to Actions and click on the delete security groups. Here we can see the status that states will not be deleted and the reason is that This is a default security group. Default security groups cannot be deleted. If it is a default security group then, the other security group is not the default security group. Let’s try to delete that. I select the other one, click on Actions and click on the Delete security groups. For this as well, we can see the status is will not be deleted and the reason is different which states 1 security group associated. This means that the security group has a dependent resource. I checked all the dependent resources here on the web console and cleared all the resources, but also I could not find the dependent resource and also could not delete the security group.
After going through deep and long research, I found the way to find the attached or dependent resources. That is by using the AWS CLI tool. I recommend you to watch this video till the end even If you don’t have the AWS CLI tool installed on your PC, because the solution may not require the AWS CLI installed on your PC and give you some other ideas to solve the problem.
And if you want to install AWS CLI tool and troubleshoot the problem as I do, you can refer to the video tutorial that I have uploaded just before this video on the YouTube channel, or you can find the link of the video in the description or you can open the link displayed on the top-right corner of the video in a new tab, install the AWS CLI tool and come back to the video.
After installing the AWS CLI tool, open the command prompt and type the command set as you see on the screen without making any modification on it. You can also get the command set on the description below.
Install & Configure the AWS CLIhttps://youtu.be/zhDAmeEOTIo

Here, we can see that, the security group having the given security group ID is the default and that is dependent on a security group having the security groupID.
From the output as shown on the screen, we know that the first security group is dependent on the second security group but the second group is not dependent to anything. That means, we are unable to delete the second security group as well because it is associated to the first security group.
That is why, using a common logic, I am going to check the Inbound rules of both the security groups to find if any security group refers to the any other security group as it’s rule or so.
Selecting the second security group, in the Inbound rules tab, I click on the Edit inbound rules. Here, we don’t see the security group referring to any other security group on its inbound rules. Let’s cancel it and check in the other security group. Select the first security group and click on edit inbound rules. Here, we can see the first rule is referring to the second security group. That is why, the first security group’s dependent resource is the second security group. Let’s remove this rule and click on the save rules.
Now, let’s go to the security groups section, select the second security group, click on Actions and click on the delete security groups. Now, we don’t get any error message or any obstruction to delete the security group. Click on the delete button and we can see the security group is successfully deleted.
Although the default security group cannot be deleted, let me show you a try. Here we can see, the reason is the default security group can not be deleted. If you want to delete it on any way, then you will have to delete the default VPC as well. Let’s check that too.
Go to the VPC dashboard, click on the VPCs, select the VPC and let’s check whether this is a default VPC or not, yes this is the default VPC, click on Actions and click on the delete vpc. Now, click on the I acknowledge check box, on the box, type delete default vpc and click on the delete button. The VPC is now successfully deleted. Now if we go to the VPC dashboard, we see the security group number is zero.

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