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sed -i 's/Also See/See Also/' plugin/**/README.md Some plugins did already use 'See Also', so it's all consistent now. Fixes: #4196 Signed-off-by: Miek Gieben <miek@miek.nl>
50 lines
1.7 KiB
Markdown
50 lines
1.7 KiB
Markdown
# metadata
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## Name
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*metadata* - enables a metadata collector.
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## Description
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By enabling *metadata* any plugin that implements [metadata.Provider
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interface](https://godoc.org/github.com/coredns/coredns/plugin/metadata#Provider) 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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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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The metadata is added by setting a label with a value in the context. These labels should be named
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`plugin/NAME`, where **NAME** is something descriptive. The only hard requirement the *metadata*
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plugin enforces is that the labels contain a slash. See the documentation for
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`metadata.SetValueFunc`.
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The value stored is a string. The empty string signals "no metadata". See the documentation for
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`metadata.ValueFunc` on how to retrieve this.
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## Syntax
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~~~
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metadata [ZONES... ]
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~~~
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* **ZONES** zones metadata should be invoked for.
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## Plugins
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`metadata.Provider` 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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Note: this method should work quickly, because it is called for every request.
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## Examples
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The *rewrite* plugin uses meta data to rewrite requests.
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## See Also
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The [Provider interface](https://godoc.org/github.com/coredns/coredns/plugin/metadata#Provider) and
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the [package level](https://godoc.org/github.com/coredns/coredns/plugin/metadata) documentation.
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