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65 lines
1.9 KiB
Groff
65 lines
1.9 KiB
Groff
.\" Generated by Mmark Markdown Processer - mmark.miek.nl
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.TH "COREDNS-METADATA" 7 "December 2019" "CoreDNS" "CoreDNS Plugins"
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.SH "NAME"
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.PP
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\fImetadata\fP - enables a metadata collector.
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.SH "DESCRIPTION"
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.PP
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By enabling \fImetadata\fP any plugin that implements metadata.Provider
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interface
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\[la]https://godoc.org/github.com/coredns/coredns/plugin/metadata#Provider\[ra] will be called for
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each DNS query, at the beginning of the process for that query, in order to add its own metadata to
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context.
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.PP
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The metadata collected will be available for all plugins, via the Context parameter provided in the
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ServeDNS function. The package (code) documentation has examples on how to inspect and retrieve
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metadata a plugin might be interested in.
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.PP
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The metadata is added by setting a label with a value in the context. These labels should be named
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\fB\fCplugin/NAME\fR, where \fBNAME\fP is something descriptive. The only hard requirement the \fImetadata\fP
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plugin enforces is that the labels contain a slash. See the documentation for
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\fB\fCmetadata.SetValueFunc\fR.
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.PP
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The value stored is a string. The empty string signals "no metadata". See the documentation for
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\fB\fCmetadata.ValueFunc\fR on how to retrieve this.
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.SH "SYNTAX"
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.PP
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.RS
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.nf
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metadata [ZONES... ]
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.fi
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.RE
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.IP \(bu 4
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\fBZONES\fP zones metadata should be invoked for.
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.SH "PLUGINS"
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.PP
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\fB\fCmetadata.Provider\fR interface needs to be implemented by each plugin willing to provide metadata
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information for other plugins. It will be called by metadata and gather the information from all
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plugins in context.
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.PP
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Note: this method should work quickly, because it is called for every request.
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.SH "EXAMPLES"
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.PP
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The \fIrewrite\fP plugin uses meta data to rewrite requests.
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.SH "ALSO SEE"
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.PP
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The Provider interface
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\[la]https://godoc.org/github.com/coredns/coredns/plugin/metadata#Provider\[ra] and
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the package level
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\[la]https://godoc.org/github.com/coredns/coredns/plugin/metadata\[ra] documentation.
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