219bfd0493
* 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
132 lines
2.9 KiB
Go
132 lines
2.9 KiB
Go
// Package cache implements a cache.
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package cache
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import (
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"log"
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"strconv"
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"strings"
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"time"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/coredns/middleware/pkg/response"
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"github.com/hashicorp/golang-lru"
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"github.com/miekg/dns"
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)
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// Cache is middleware that looks up responses in a cache and caches replies.
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// It has a success and a denial of existence cache.
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type Cache struct {
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Next middleware.Handler
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Zones []string
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ncache *lru.Cache
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ncap int
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nttl time.Duration
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pcache *lru.Cache
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pcap int
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pttl time.Duration
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}
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// Return key under which we store the item.
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func key(m *dns.Msg, t response.Type, do bool) string {
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if m.Truncated {
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// TODO(miek): wise to store truncated responses?
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return ""
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}
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if t == response.OtherError {
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return ""
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}
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qtype := m.Question[0].Qtype
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qname := strings.ToLower(m.Question[0].Name)
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return rawKey(qname, qtype, do)
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}
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func rawKey(qname string, qtype uint16, do bool) string {
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if do {
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return "1" + qname + "." + strconv.Itoa(int(qtype))
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}
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return "0" + qname + "." + strconv.Itoa(int(qtype))
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}
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// ResponseWriter is a response writer that caches the reply message.
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type ResponseWriter struct {
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dns.ResponseWriter
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*Cache
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}
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// WriteMsg implements the dns.ResponseWriter interface.
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func (c *ResponseWriter) WriteMsg(res *dns.Msg) error {
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do := false
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mt, opt := response.Typify(res)
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if opt != nil {
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do = opt.Do()
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}
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key := key(res, mt, do)
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duration := c.pttl
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if mt == response.NameError || mt == response.NoData {
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duration = c.nttl
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}
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msgTTL := minMsgTTL(res, mt)
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if msgTTL < duration {
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duration = msgTTL
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}
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if key != "" {
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c.set(res, key, mt, duration)
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cacheSize.WithLabelValues(Success).Set(float64(c.pcache.Len()))
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cacheSize.WithLabelValues(Denial).Set(float64(c.ncache.Len()))
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}
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setMsgTTL(res, uint32(duration.Seconds()))
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return c.ResponseWriter.WriteMsg(res)
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}
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func (c *ResponseWriter) set(m *dns.Msg, key string, mt response.Type, duration time.Duration) {
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if key == "" {
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log.Printf("[ERROR] Caching called with empty cache key")
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return
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}
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switch mt {
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case response.NoError, response.Delegation:
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i := newItem(m, duration)
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c.pcache.Add(key, i)
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case response.NameError, response.NoData:
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i := newItem(m, duration)
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c.ncache.Add(key, i)
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case response.OtherError:
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// don't cache these
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default:
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log.Printf("[WARNING] Caching called with unknown classification: %d", mt)
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}
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}
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// Write implements the dns.ResponseWriter interface.
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func (c *ResponseWriter) Write(buf []byte) (int, error) {
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log.Printf("[WARNING] Caching called with Write: not caching reply")
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n, err := c.ResponseWriter.Write(buf)
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return n, err
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}
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const (
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maxTTL = 1 * time.Hour
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maxNTTL = 30 * time.Minute
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minTTL = 5 * time.Second
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defaultCap = 10000 // default capacity of the cache.
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// Success is the class for caching postive caching.
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Success = "success"
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// Denial is the class defined for negative caching.
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Denial = "denial"
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)
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