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* middleware/metrics: add more metrics middleware/cache: Add metrics for number of elements in the cache. Also export the total size. Update README to detail the new metrics. middleware/metrics Move metrics into subpackage called "vars". This breaks the import cycle and is cleaner. This allows vars.Report to be used in the the dnsserver to log refused queries. middleware/metrics: tests Add tests to the metrics framework. The metrics/test subpackage allows scraping of the local server. Do a few test scrape of the metrics that are defined in the metrics middleware. This also allows metrics integration tests to check if the caching and dnssec middleware export their metrics correctly. * update README * typos * fix tests
59 lines
1.8 KiB
Markdown
59 lines
1.8 KiB
Markdown
# cache
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*cache* enables a frontend cache.
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## Syntax
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~~~ txt
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cache [TTL] [ZONES...]
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~~~
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* **TTL** max TTL in seconds. If not specified, the maximum TTL will be used which is 1 hour for
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noerror responses and half an hour for denial of existence ones.
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* **ZONES** zones it should cache for. If empty, the zones from the configuration block are used.
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Each element in the cache is cached according to its TTL (with **TTL** as the max).
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For the negative cache, the SOA's MinTTL value is used. A cache can contain up to 10,000 items by
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default.
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If you want more control:
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~~~ txt
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cache [TTL] [ZONES...] {
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success CAPACITY [TTL]
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denial CAPACITY [TTL]
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}
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~~~
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* **TTL** and **ZONES** as above.
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* `success`, override the settings for caching succesful responses, **CAPACITY** indicates the maximum
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number of packets we cache before we start evicting (LRU). **TTL** overrides the cache maximum TTL.
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* `denial`, override the settings for caching denial of existence responses, **CAPACITY** indicates the maximum
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number of packets we cache before we start evicting (LRU). **TTL** overrides the cache maximum TTL.
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There is a third category (`error`) but those responses are never cached.
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The minimum TTL allowed on resource records is 5 seconds.
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## Metrics
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If monitoring is enabled (via the *prometheus* directive) then the following metrics are exported:
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* coredns_cache_size_guage{type} - total elements in the case, type is either "denial" or "success".
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* coredns_cache_capacity_guage{type} - total capacity of the cache, type is either "denial" or "success".
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## Examples
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Enable caching for all zones, but cap everything to a TTL of 10 seconds:
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~~~
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cache 10
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~~~
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Proxy to Google Public DNS and only cache responses for example.org (or below).
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~~~
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proxy . 8.8.8.8:53
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cache example.org
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~~~
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