Amazon Linux 2 in a Docker missing hostname command

Question

We're developing an app running in a Docker container: on-premises, so this question is purely about Amazon Linux 2 and has nothing to do with AWS.

I'm migrating the image from the one based on `centos:7` to `amazoncorretto:17`, based on `amazonlinux:2`. Surprisingly, `hostname -f`, which is used to get an FQDN inside a container, is failing because Amazon Linux 2 doesn't have `hostname`.

We do need the host FQDN, and it gets propagated to containers either via host networking or via Docker's Swarm `--hostname {{.Node.Hostname}}`, etc.

I have two questions:
1. How do I get an FQDN without `hostname`?
2. Why did Amazon Linux 2 remove it? Even Alpine has it. Would it make sense to put it back?

Accepted Answer

Hi,

You can get the hostname command using yum
```
yum install hostname
```
Another alternative would be to build your own customized image from amazoncorretto:17 with hostname preinstalled so as to avoid the need for any install during runtime.

--Syd

Amazon Linux 2 in a Docker missing hostname command

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