7.5. Troubleshooting CoreDNS

This section provides troubleshooting information for the Configuring CoreDNS for K3s phase of Running the LOCKSS Installer.

7.5.1. CoreDNS does not allow a loopback address to be given to Kubernetes pods as an upstream DNS server

If both /etc/resolv.conf and /run/systemd/resolve/resolv.conf (files used to list the IP address of DNS servers) contain loopback addresses, CoreDNS (a component of the K3s Kubernetes cluster that handles DNS resolution) will not work properly 1. If install-lockss detects this situation, you will see a warning message including CoreDNS does not allow a loopback address to be given to Kubernetes pods as an upstream DNS server, and the following prompt 2:

IP address(es) of DNS resolvers, separated by ';'

Enter a semicolon-separated list of DNS server IP addresses that are not loopback addresses or hit Enter to accept the proposed value.

7.5.2. Post-Installation Changes to DNS

If the DNS settings of your system change after K3s is initially installed (for example if DNS servers are added or removed), run this command (which is relative to the lockss-installer-directory) as a privileged user who can become root via sudo 3:

scripts/install-lockss --configure-coredns

This will run only the Configuring CoreDNS for K3s phase of install-lockss.


Footnotes

1

References:

2

See Configuring CoreDNS for K3s.

3

See Running Commands as a Privileged User.