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diff --git a/middleware/cache/README.md b/middleware/cache/README.md deleted file mode 100644 index 6477fe891..000000000 --- a/middleware/cache/README.md +++ /dev/null @@ -1,68 +0,0 @@ -# cache - -*cache* enables a frontend cache. It will cache all records except zone transfers and metadata records. - -## Syntax - -~~~ txt -cache [TTL] [ZONES...] -~~~ - -* **TTL** max TTL in seconds. If not specified, the maximum TTL will be used which is 3600 for - noerror responses and 1800 for denial of existence ones. - Setting a TTL of 300 *cache 300* would cache the record up to 300 seconds. -* **ZONES** zones it should cache for. If empty, the zones from the configuration block are used. - -Each element in the cache is cached according to its TTL (with **TTL** as the max). -For the negative cache, the SOA's MinTTL value is used. A cache can contain up to 10,000 items by -default. A TTL of zero is not allowed. - -If you want more control: - -~~~ txt -cache [TTL] [ZONES...] { - success CAPACITY [TTL] - denial CAPACITY [TTL] - prefetch AMOUNT [[DURATION] [PERCENTAGE%]] -} -~~~ - -* **TTL** and **ZONES** as above. -* `success`, override the settings for caching successful responses, **CAPACITY** indicates the maximum - number of packets we cache before we start evicting (*randomly*). **TTL** overrides the cache maximum TTL. -* `denial`, override the settings for caching denial of existence responses, **CAPACITY** indicates the maximum - number of packets we cache before we start evicting (LRU). **TTL** overrides the cache maximum TTL. - There is a third category (`error`) but those responses are never cached. -* `prefetch`, will prefetch popular items when they are about to be expunged from the cache. - Popular means **AMOUNT** queries have been seen no gaps of **DURATION** or more between them. - **DURATION** defaults to 1m. Prefetching will happen when the TTL drops below **PERCENTAGE**, - which defaults to `10%`. Values should be in the range `[10%, 90%]`. Note the percent sign is - mandatory. **PERCENTAGE** is treated as an `int`. - -The minimum TTL allowed on resource records is 5 seconds. - -## Metrics - -If monitoring is enabled (via the *prometheus* directive) then the following metrics are exported: - -* coredns_cache_size{type} - Total elements in the cache by cache type. -* coredns_cache_capacity{type} - Total capacity of the cache by cache type. -* coredns_cache_hits_total{type} - Counter of cache hits by cache type. -* coredns_cache_misses_total - Counter of cache misses. - -Cache types are either "denial" or "success". - -## Examples - -Enable caching for all zones, but cap everything to a TTL of 10 seconds: - -~~~ -cache 10 -~~~ - -Proxy to Google Public DNS and only cache responses for example.org (or below). - -~~~ -proxy . 8.8.8.8:53 -cache example.org -~~~ |