DNS sub-server creation leaves inconsistent slave state after "Missing file to read" in feature-dns.pl

[jens-ingo]

Observed on:

• Debian Linux 11
• Webmin 2.621
• Virtualmin 8.1.0 GPL
• Authentic Theme 26.22

System:

• BIND with master + multiple slave authoritative DNS servers
• DNS slaves use zone transfers from master
• BIND views enabled in slave configuration for one DNS server

Issue:

When saving or creating a sub-server with DNS enabled, Virtualmin reports:

DNS for domain failed : Missing file to read at virtual_server::/usr/share/webmin/virtual-server/feature-dns.pl line 4026

The UI simultaneously shows:

Adding new DNS zone .. done

Observed result:

The zone is not always created consistently across authoritative DNS servers.

In this case:

• master zone was created on the primary server
• one slave returned NXDOMAIN
• one slave returned SERVFAIL
• one slave had an invalid local zone file
• manual BIND cleanup and slave retransfer were required

This produced intermittent production failures because different authoritative DNS servers answered differently depending on which one clients reached.

Practical impact:

Users experienced random connection failures to a production CRM host because DNS resolution became inconsistent across authoritative nameservers.

Manual investigation showed:

• partial slave zone creation
• invalid transferred zone file on one slave
• one slave BIND config became inconsistent after zone insertion
• manual correction required before all slaves returned identical answers again

After cleanup, all authoritative servers answered correctly again.

Possible cause:

feature-dns.pl appears to attempt read_file_lines() before file state is fully consistent, or before slave-side zone state is safely established.

This may especially appear in environments using:

• BIND master/slave topology
• authoritative slave replication
• views

The issue is not only cosmetic: it can lead to intermittent authoritative DNS inconsistency in production.

The issue seems related to recent DNS regressions already reported around Virtualmin 8.x.

I can provide exact zone snippets if useful.

[iliaross]

Hello,

Thanks for the heads-up!

Could you please apply the following patch and let us know if it resolves your issue:

webmin patch https://github.com/virtualmin/virtualmin-gpl/commit/bdf7e50