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fix(local): handle names under .localhost. (#8151)

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This commit is contained in:
Immanuel Tikhonov
2026-06-24 13:31:31 +04:00
committed by GitHub
parent faeb8ba699
commit e45ad5f87a
7 changed files with 211 additions and 38 deletions
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45
man/coredns-local.7
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@@ -1,24 +1,26 @@
.\" Generated by Mmark Markdown Processer - mmark.miek.nl
.TH "COREDNS-LOCAL" 7 "March 2026" "CoreDNS" "CoreDNS Plugins"
.\" Generated by Mmark Markdown Processor - mmark.miek.nl
.TH "COREDNS-LOCAL" 7 "June 2026" "CoreDNS" "CoreDNS Plugins"
.SH "NAME"
.PP
\fIlocal\fP - respond to local names.
\fIlocal\fP \- respond to local names.
.SH "DESCRIPTION"
.PP
\fIlocal\fP will respond with a basic reply to a "local request". Local request are defined to be
names in the following zones: localhost, 0.in-addr.arpa, 127.in-addr.arpa and 255.in-addr.arpa \fIand\fP
any query asking for \fB\fClocalhost.<domain>\fR. When seeing the latter a metric counter is increased and
if \fIdebug\fP is enabled a debug log is emitted.
\fIlocal\fP will respond with a basic reply to a "local request". Local requests are defined to be
names in the following zones: localhost, 0.in\-addr.arpa, 127.in\-addr.arpa and 255.in\-addr.arpa,
any query under \fB\fC.localhost.\fR, and, by default for backward compatibility, any query prefixed by
\fB\fClocalhost.\fR. When seeing one of the non\-apex localhost forms a metric counter is increased and if
\fIdebug\fP is enabled a debug log is emitted.
.PP
With \fIlocal\fP enabled any query falling under these zones will get a reply. The prevents the query
With \fIlocal\fP enabled any query falling under these zones will get a reply. This prevents the query
from "escaping" to the internet and putting strain on external infrastructure.
.PP
The zones are mostly empty, only \fB\fClocalhost.\fR address records (A and AAAA) are defined and a
\fB\fC1.0.0.127.in-addr.arpa.\fR reverse (PTR) record.
The zones are mostly empty, only \fB\fClocalhost.\fR, names under \fB\fC.localhost.\fR, and legacy
\fB\fClocalhost.<domain>\fR names return loopback address records (A and AAAA), and only
\fB\fC1.0.0.127.in-addr.arpa.\fR has a reverse (PTR) record.
.SH "SYNTAX"
.PP
@@ -30,13 +32,32 @@ local
.fi
.RE
.PP
.RS
.nf
local {
localhost\_prefix on|off
}
.fi
.RE
.PP
\fB\fClocalhost_prefix\fR controls the legacy \fB\fClocalhost.<domain>\fR behavior. The default is \fB\fCon\fR for
backward compatibility. Set it to \fB\fCoff\fR to only treat names under \fB\fC.localhost.\fR as special, which
matches RFC 6761. The legacy prefix behavior is deprecated and may be disabled by default in a
future release.
.SH "METRICS"
.PP
If monitoring is enabled (via the \fIprometheus\fP plugin) then the following metric is exported:
.IP \(bu 4
\fB\fCcoredns_local_localhost_requests_total{}\fR - a counter of the number of \fB\fClocalhost.<domain>\fR
requests CoreDNS has seen. Note this does \fInot\fP count \fB\fClocalhost.\fR queries.
\fB\fCcoredns_local_localhost_requests_total{}\fR \- a counter of the number of non\-apex localhost
special\-case queries CoreDNS has seen. This includes \fB\fC.localhost.\fR names and, when
\fB\fClocalhost_prefix\fR is \fB\fCon\fR, legacy \fB\fClocalhost.<domain>\fR names. It does \fInot\fP count \fB\fClocalhost.\fR
queries.
.PP