.chezmoi.hostname source priority

[stinovlas]

Hi! I use .chezmoi.hostname variable in my scripts to differentiate between individual machines. I bumped into a weird situation. In one of my machine, I use /etc/hosts to point different services to 127.0.0.1, for development reasons. This totally wrecks the value of .chezmoi.hostname. It doesn't matter what /etc/hostname contains or what hostname command returns. It just uses the first non-local domain from /etc/hosts and considers that to be a hostname.

I find this really confusing. Why did you decide to prioritize /etc/hosts parsing before /etc/hostname? And is there any way to override this auto-detected value?

[twpayne]

What is the contents of your /etc/hosts file?

[twpayne]

chezmoi is looking for a fully-qualified domain name associated with a loopback address. Before you added alfheim.local, the first FQDN with a loopback address in your /etc/hosts is project1.my.work.domain.cz. chezmoi is working as intended here as your /etc/hosts clearly states that project1.my.work.domain.cz has IP address 127.0.0.1, i.e. is the localhost.

The fix for you is to include your actual FQDN earlier in the file, as you did when you added alfheim.local.

chezmoi's hostname detection has evolved to be robust across multiple operating systems and configurations. It cannot, however, detect misconfigurations.

If you have to edit /etc/hosts to test your software, I strongly recommend exploring the topic of service discovery.

[stinovlas]

I wouldn't say my system is misconfigured. When I run hostnamectl hostname, I get correct value, alfheim. The same value is returned by hostname command and also stored in /etc/hostname. For all intents and purposes, the hostname of my machine is alfheim. But chezmoi tries to parse my /etc/hosts instead and makes assumptions based on its content. This is highly non-standard for a linux app.

I'm not saying that adding additional hostnames to /etc/hosts is a good practice, but that's not the point. Of course, I could add the correct hostname to chezmoi.toml and use it instead of .chezmoi.hostname, but that seems like unnecessary duplication.

But after all, there are some ways around this and chezmoi is still awesome regardless. This is just one thing that's bitten me and I found it really confusing. Maybe chezmoi could call hostname --fqdn which returns hostname in full FQDN format (or some Go equivalent)? That would fix the hostname resolution issue quite nicely (because the whole problems stems from the problem that chezmoi expects . in the hostname and os.Hostname() does not return FQDN).

[halostatue]

chezmoi uses several different steps in hostname resolution, as I mentioned in a comment on #3655. We also explicitly do not call hostname or hostnamectl (mentioned in a comment on #3407).

Both of those comments have links to other discussions on issues and PRs.

[twpayne]

Note that you can use hostnamectl with chezmoi. Put the following in your config file template:

[data]
    hostname = {{ output "hostnamectl" "hostname" | trim | quote }}

and then use {{ .hostname }} in your templates.

[stinovlas]

This is a good suggestion and it occurred to me as well. This is probably the way to go.