How to update yum without internet access on EC2

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As a part of our AWS Support services, we often receive similar queries from our AWS Customers.

Today, let’s see how our Support Engineers help our customers to update yum without internet access on the Amazon EC2 instances.

 

Update yum without internet access on EC2

 

The Amazon Linux repositories are stored in Amazon S3 buckets. Therefore, when the yum processes, it downloads packages from those buckets on our instance.

We need to create an S3 Amazon VPC gateway endpoint to update or install packages on the instance without an internet connection. In the S3 VPC gateway endpoint, we must include a policy that allows access to the repositories buckets. Then associate it to the routing table for the private subnet in which the instance resides.

Note the following points before proceeding with the steps to update yum without internet access on the Amazon EC2 instances:

• Be sure that the security group attached to the Amazon EC2 instance allows outbound HTTP traffic.
• Confirm that the security group attached to the S3 VPC endpoint allows inbound HTTP traffic from the EC2 instance.
• Also, make sure that the network ACLs related to the Amazon EC2 instance allows the following:

Port 80 and 443  to the Regional S3 service.

Ephemeral TCP ports from the Regional S3 service. Ephemeral ports range from 1024 to 65535.

Add the S3 CIDR to the network ACL, use 0.0.0.0/0 as the S3 CIDR. However, keep in mind that the S3 CIDRs can change at any time.

 

Steps to install and update packages in Amazon Linux instance

 

1. At first, Log in to the AWS Management Console and then open the Amazone EC2 console.

2. Select the instance.

3. Note the VPC ID and Subnet ID from the Networking tab.

4. Now, open the Amazon VPC console.

5. Select Subnets and then select the Subnet ID.

6. Note the Route Table ID from the Route Table tab.

7. Select Endpoints and then select Create Endpoint.

8. We need to create the endpoint using the following information:

Select com.amazonaws.[REGION].s3 for the Service name option. Replace the REGION with the location (for example: com.amazonaws.us-west-2.s3)

For VPC, select the VPC ID for the instance.

9. For policy, select Full Access or Custom.

By selecting Full Access, the endpoint policy allows full access to Amazon S3.

But if we select Custom, we must allow the API call s3:GetObject on the Amazon Linux repositories buckets:

For Amazon Linux 1

The repositories are hosted by S3 buckets arn:aws:s3:::packages.region.amazonaws.com and arn:aws:s3:::repo.region.amazonaws.com.

An example policy for allowing the s3:GetObject API call access is shown below:

{
"Statement": [
{
"Principal": "*",
"Action": [
"s3:GetObject"
],
"Effect": "Allow",
"Resource": [
"arn:aws:s3:::packages.region.amazonaws.com/*",
"arn:aws:s3:::repo.region.amazonaws.com/*"
]
}
]
}

For Amazon Linux 2

The repositories are hosted by S3 buckets arn:aws:s3:::amazonlinux.region.amazonaws.com and arn:aws:s3:::amazonlinux-2-repos-region/* .

An example policy for allowing the s3:GetObject API call.

{
"Statement": [
{
"Principal": "*",
"Action": [
"s3:GetObject"
],
"Effect": "Allow",
"Resource": [
"arn:aws:s3:::amazonlinux.region.amazonaws.com/*",
"arn:aws:s3:::amazonlinux-2-repos-region/*"
]
}
]
}

Replace the Region in the Resource ARN with our AWS Region.

8.Select Create endpoint.

And now we can install and update packages in the Amazon Linux instance after creating the S3 VPC endpoint.

Note: We must have internet access through one of the following gateways to enable third-party repositories:

• Internet gateway
• NAT instance
• NAT gateway
• VPN

[Need help with more AWS queries? We’d be happy to assist]

 

Conclusion

 

To conclude, today we discussed the steps followed by our Support Engineers to help our customers to update yum without internet access on EC2.