Let's use getent ahosts instead of dig +short

[vazhnov]

Hello!

Thank you for the project!

I recommend to use getent ahosts NAME instead of dig +short NAME in this course, for both: manual steps in the documentation and scripts.

getent is a tool usually included into even very minimalistic OS setup.

getent follows /etc/nsswitch.conf rules (reads /etc/hosts, mDNS, etc.), while dig is mainly designed to troubleshoot external DNS servers. Much more details about the difference can be found in https://unix.stackexchange.com/questions/20784/ (or in my brief summary).

I think using dig is a bad practice when custom records in /etc/hosts are used. getent is designed for such cases.

I'm currently in step 08 and I see no issues with this replacement.

Also I've checked: using getent ahosts is compatible with both Vagrant images, Ubuntu and Debian, to do steps of this course.

Currently script vagrant/ubuntu/update-dns.sh fails to apply in Debian let's skip this for dedicated issue.

[fireflycons]

I'm using dig +short because it returns only the IP address with no need to muck about with awk to get it. getent will return IP+HOST
The lab's not millisecond performance critical so if dig does waste time getting a negative response from DNS before checking hosts file, not really an issue.

[vazhnov]

I'm using dig +short because it returns only the IP address with no need to muck about with awk to get it. getent will return IP+HOST

I agree, I have to use getent ahosts example.com | awk '{ print $1 ; exit }' to return only one IP-address without name.

The lab's not millisecond performance critical so if dig does waste time getting a negative response from DNS before checking hosts file, not really an issue.

The thing is — dig doesn't use /etc/hosts at all. In case of the lab, I think that systemd-resolved is doing that.

This change is also about to teach people to use proper tools.