WIP: autopath as middleware (#859)

autopath as middleware

middleware/autopath/setup.go

@@ -0,0 +1,87 @@
+package autopath
+
+import (
+	"fmt"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/middleware"
+
+	"github.com/mholt/caddy"
+	"github.com/miekg/dns"
+)
+
+func init() {
+	caddy.RegisterPlugin("autopath", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+
+}
+
+func setup(c *caddy.Controller) error {
+	ap, mw, err := autoPathParse(c)
+	if err != nil {
+		return middleware.Error("autopath", err)
+	}
+
+	c.OnStartup(func() error {
+		// So we know for sure the mw is initialized.
+		m := dnsserver.GetMiddleware(c, mw)
+		switch mw {
+		case "kubernetes":
+			m = m
+			//if k, ok := m.(kubernetes.Kubernetes); ok {
+			//&ap.searchFunc = k.AutoPath
+			//}
+		}
+		return nil
+	})
+
+	dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
+		ap.Next = next
+		return ap
+	})
+
+	return nil
+}
+
+var allowedMiddleware = map[string]bool{
+	"@kubernetes": true,
+}
+
+func autoPathParse(c *caddy.Controller) (*AutoPath, string, error) {
+	ap := new(AutoPath)
+	mw := ""
+
+	for c.Next() {
+		zoneAndresolv := c.RemainingArgs()
+		if len(zoneAndresolv) < 1 {
+			return nil, "", fmt.Errorf("no resolv-conf specified")
+		}
+		resolv := zoneAndresolv[len(zoneAndresolv)-1]
+		if resolv[0] == '@' {
+			_, ok := allowedMiddleware[resolv]
+			if ok {
+				mw = resolv[1:]
+			}
+		} else {
+			// assume file on disk
+			rc, err := dns.ClientConfigFromFile(resolv)
+			if err != nil {
+				return nil, "", fmt.Errorf("failed to parse %q: %v", resolv, err)
+			}
+			ap.search = rc.Search
+			middleware.Zones(ap.search).Normalize()
+			ap.search = append(ap.search, "") // sentinal value as demanded.
+		}
+		ap.Zones = zoneAndresolv[:len(zoneAndresolv)-1]
+		if len(ap.Zones) == 0 {
+			ap.Zones = make([]string, len(c.ServerBlockKeys))
+			copy(ap.Zones, c.ServerBlockKeys)
+		}
+		for i, str := range ap.Zones {
+			ap.Zones[i] = middleware.Host(str).Normalize()
+		}
+	}
+	return ap, mw, nil
+}