Does Alpine resolve DNS properly?
To anybody who has ever used containers, Alpine is a well known base operating system layer to many popular and widely used container images in use today. By design, it's a cut down minimal OS layer using the excellent busybox and musl libc C library. By using these alternatives to GNU Coreutils and GNU glibc C Library, it provides a base OS container layer that allows you to build and run very small Linux containers.
This week I was asked to look at a problem where an application team could not resolve a key DNS name used on our internal network when running their application within the container - their first thought was a problem with the OpenShift/Kubernetes environment where the container was running.
Unfortunately, the company I work for doesn't like us to disclose internal proprietary network information, so for the purposes of the post, let's say the DNS name being queried is vis.company.com (very important service). All IPs and some other data in the extracts below have been manually changed to private RFC1918 addresses or redacted too.
The first thing to do was to perform my own DNS lookup of vis.company.com. This worked fine from both my Linux workstation and Windows laptop.
