Unable to install services on my instance. Take Two.

Question

What am I doing wrong?

I could have swore I am doing it right.

[ec2-user@localhost ~]$ sudo yum install -y telnet-server

Amazon Linux 2023 repository 0.0 B/s | 0 B 00:00
Errors during downloading metadata for repository 'amazonlinux':

Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/core/mirrors/2023.2.20231113/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com] Error: Failed to download metadata for repo 'amazonlinux': Cannot prepare internal mirrorlist: Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/core/mirrors/2023.2.20231113/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com] Amazon Linux 2023 Kernel Livepatch repository 0.0 B/s | 0 B 00:00
Errors during downloading metadata for repository 'kernel-livepatch':
Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/kernel-livepatch/mirrors/al2023/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com] Error: Failed to download metadata for repo 'kernel-livepatch': Cannot prepare internal mirrorlist: Curl error (6): Couldn't resolve host name for https://al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com/kernel-livepatch/mirrors/al2023/x86_64/mirror.list [Could not resolve host: al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com] Ignoring repositories: amazonlinux, kernel-livepatch No match for argument: telnet-server Error: Unable to find a match: telnet-server

Please instruct me how to resolve this problem, instead of just linking me to rhetoric.

Filtering through a link's contents will only further confuse me, as I had this working once. AWS just decided to shut down all my instances, and deleted all my saved security groups and keypairs, so I am trying to replicate what i did before from nothing.

Accepted Answer

The DNS name **al2023-repos-default-de612dc2.s3.dualstack.default.amazonaws.com** can't be resolved, because it's invalid.

As to how this has happened .... the YUM repos are defined in files in the files in **/etc/yum.repos.d/**, the key bits are the rows of the form:
```
mirrorlist=https://al2023-repos-$awsregion-de612dc2.s3.dualstack.$awsregion.$awsdomain/core/mirrors/....
```

The shell variables should be expanded when the `yum` command is run, **$awsregion** should become the region the EC2 is provisioned in, and **$awsdomain** should become **amazonaws.com**.

The second one is happening on your EC2, the first one isn't (so it's being expanded to **default** instead).

In which region is the EC2 provisioned? And what are the contents of these files (they are ASCII text files so it's safe to `cat` them)?
```
/etc/dnf/vars/awsregion

/etc/dnf/vars/awsdomain

/etc/cloud/cloud.cfg.d/10_aws_dnfvars.cfg

/etc/yum.repos.d/amazonlinux.repo
```

Also (and this may not be related, but just in case) the shell prompt has changed from the expected **ec2-user@ip-172-31-0-10** to **ec2-user@localhost**. What change was made on the system to effect this?

Answer

So the region was the problem. However, on the incorrect region, I was still unable to make a successful instance that actually worked.

Unable to install services on my instance. Take Two.

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