bc301be5ee
Adds a middleware to enable tracing with OpenTracing/OpenZipkin. Enabling tracing will have a large impact on performance so it is not advisable in production.
87 lines
1.6 KiB
Go
87 lines
1.6 KiB
Go
package trace
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import (
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"fmt"
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"strings"
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"sync"
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"github.com/miekg/coredns/core/dnsserver"
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"github.com/miekg/coredns/middleware"
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"github.com/mholt/caddy"
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)
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func init() {
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caddy.RegisterPlugin("trace", caddy.Plugin{
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ServerType: "dns",
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Action: setup,
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})
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}
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func setup(c *caddy.Controller) error {
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t, err := traceParse(c)
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if err != nil {
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return middleware.Error("trace", err)
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}
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dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
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t.Next = next
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return t
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})
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traceOnce.Do(func() {
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c.OnStartup(t.OnStartup)
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})
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return nil
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}
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func traceParse(c *caddy.Controller) (*Trace, error) {
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var (
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tr = &Trace{Endpoint: defEP, EndpointType: defEpType}
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err error
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)
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cfg := dnsserver.GetConfig(c)
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tr.ServiceEndpoint = cfg.ListenHost + ":" + cfg.Port
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for c.Next() {
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if c.Val() == "trace" {
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var err error
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args := c.RemainingArgs()
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switch len(args) {
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case 0:
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tr.Endpoint, err = normalizeEndpoint(tr.EndpointType, defEP)
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case 1:
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tr.Endpoint, err = normalizeEndpoint(defEpType, args[0])
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case 2:
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tr.EndpointType = strings.ToLower(args[0])
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tr.Endpoint, err = normalizeEndpoint(tr.EndpointType, args[1])
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default:
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err = c.ArgErr()
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}
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if err != nil {
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return tr, err
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}
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}
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}
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return tr, err
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}
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func normalizeEndpoint(epType, ep string) (string, error) {
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switch epType {
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case "zipkin":
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if strings.Index(ep, "http") == -1 {
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ep = "http://" + ep + "/api/v1/spans"
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}
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return ep, nil
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default:
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return "", fmt.Errorf("Tracing endpoint type '%s' is not supported.", epType)
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}
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}
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var traceOnce sync.Once
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const (
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defEP = "localhost:9411"
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defEpType = "zipkin"
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)
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