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
68 lines
2.3 KiB
Go
68 lines
2.3 KiB
Go
// Package middleware provides some types and functions common among middleware.
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package middleware
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import (
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"fmt"
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"github.com/miekg/dns"
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"golang.org/x/net/context"
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)
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type (
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// Middleware is the middle layer which represents the traditional
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// idea of middleware: it chains one Handler to the next by being
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// passed the next Handler in the chain.
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Middleware func(Handler) Handler
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// Handler is like dns.Handler except ServeDNS may return an rcode
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// and/or error.
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//
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// If ServeDNS writes to the response body, it should return a status
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// code. If the status code is not one of the following:
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//
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// * SERVFAIL (dns.RcodeServerFailure)
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//
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// * REFUSED (dns.RecodeRefused)
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//
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// * FORMERR (dns.RcodeFormatError)
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//
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// * NOTIMP (dns.RcodeNotImplemented)
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//
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// CoreDNS assumes *no* reply has yet been written. All other response
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// codes signal other handlers above it that the response message is
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// already written, and that they should not write to it also.
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//
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// If ServeDNS encounters an error, it should return the error value
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// so it can be logged by designated error-handling middleware.
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//
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// If writing a response after calling another ServeDNS method, the
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// returned rcode SHOULD be used when writing the response.
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//
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// If handling errors after calling another ServeDNS method, the
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// returned error value SHOULD be logged or handled accordingly.
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//
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// Otherwise, return values should be propagated down the middleware
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// chain by returning them unchanged.
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Handler interface {
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ServeDNS(context.Context, dns.ResponseWriter, *dns.Msg) (int, error)
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Name() string
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}
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// HandlerFunc is a convenience type like dns.HandlerFunc, except
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// ServeDNS returns an rcode and an error. See Handler
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// documentation for more information.
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HandlerFunc func(context.Context, dns.ResponseWriter, *dns.Msg) (int, error)
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)
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// ServeDNS implements the Handler interface.
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func (f HandlerFunc) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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return f(ctx, w, r)
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}
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func (f HandlerFunc) Name() string { return "handlerfunc" }
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// Error returns err with 'middleware/name: ' prefixed to it.
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func Error(name string, err error) error { return fmt.Errorf("%s/%s: %s", "middleware", name, err) }
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// Namespace is the namespace used for the metrics.
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const Namespace = "coredns"
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