16504234e5
* plugin/forward: on demand healtchecking Only start doing health checks when we encouner an error (any error). This uses the new pluing/pkg/up package to abstract away the actual checking. This reduces the LOC quite a bit; does need more testing, unit testing and tcpdumping a bit. * fix tests * Fix readme * Use pkg/up for healthchecks * remove unused channel * more cleanups * update readme * * Again do go generate and go build; still referencing the wrong forward repo? Anyway fixed. * Use pkg/up for doing the healtchecks to cut back on unwanted queries * Change up.Func to return an error instead of a boolean. * Drop the string target argument as it doesn't make sense. * Add healthcheck test on failing to get an upstream answer. TODO(miek): double check Forward and Lookup and how they interact with HC, and if we correctly call close() on those * actual test * Tests here * more tests * try getting rid of host * Get rid of the host indirection * Finish removing hosts * moar testing * import fmt * field is not used * docs * move some stuff * bring back health_check * maxfails=0 test * git and merging, bah * review
63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
// Package forward implements a forwarding proxy. It caches an upstream net.Conn for some time, so if the same
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// client returns the upstream's Conn will be precached. Depending on how you benchmark this looks to be
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// 50% faster than just openening a new connection for every client. It works with UDP and TCP and uses
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// inband healthchecking.
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package forward
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import (
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"strconv"
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"time"
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"github.com/coredns/coredns/request"
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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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func (p *Proxy) connect(ctx context.Context, state request.Request, forceTCP, metric bool) (*dns.Msg, error) {
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start := time.Now()
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proto := state.Proto()
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if forceTCP {
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proto = "tcp"
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}
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conn, err := p.Dial(proto)
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if err != nil {
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return nil, err
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}
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// Set buffer size correctly for this client.
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conn.UDPSize = uint16(state.Size())
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if conn.UDPSize < 512 {
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conn.UDPSize = 512
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}
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conn.SetWriteDeadline(time.Now().Add(timeout))
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if err := conn.WriteMsg(state.Req); err != nil {
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conn.Close() // not giving it back
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return nil, err
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}
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conn.SetReadDeadline(time.Now().Add(timeout))
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ret, err := conn.ReadMsg()
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if err != nil {
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conn.Close() // not giving it back
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return nil, err
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}
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p.Yield(conn)
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if metric {
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rc, ok := dns.RcodeToString[ret.Rcode]
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if !ok {
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rc = strconv.Itoa(ret.Rcode)
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}
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RequestCount.WithLabelValues(p.addr).Add(1)
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RcodeCount.WithLabelValues(rc, p.addr).Add(1)
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RequestDuration.WithLabelValues(p.addr).Observe(time.Since(start).Seconds())
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}
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return ret, nil
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}
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