Make CoreDNS a server type plugin for Caddy (#220)

* Make CoreDNS a server type plugin for Caddy

Remove code we don't need and port all middleware over. Fix all tests
and rework the documentation.

Also make `go generate` build a caddy binary which we then copy into
our directory. This means `go build`-builds remain working as-is.

And new etc instances in each etcd test for better isolation.
Fix more tests and rework test.Server with the newer support Caddy offers.

Fix Makefile to support new mode of operation.

1 files changed, 66 insertions, 0 deletions

diff --git a/middleware/cache/setup.go b/middleware/cache/setup.go
new file mode 100644
index 000000000..ab7f423f2
--- /dev/null
+++ b/middleware/cache/setup.go
@@ -0,0 +1,66 @@
+package cache
+
+import (
+	"strconv"
+
+	"github.com/miekg/coredns/core/dnsserver"
+	"github.com/miekg/coredns/middleware"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("cache", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+}
+
+// Cache sets up the root file path of the server.
+func setup(c *caddy.Controller) error {
+	ttl, zones, err := cacheParse(c)
+	if err != nil {
+		return err
+	}
+	dnsserver.GetConfig(c).AddMiddleware(func(next dnsserver.Handler) dnsserver.Handler {
+		return NewCache(ttl, zones, next)
+	})
+
+	return nil
+}
+
+func cacheParse(c *caddy.Controller) (int, []string, error) {
+	var (
+		err     error
+		ttl     int
+		origins []string
+	)
+
+	for c.Next() {
+		if c.Val() == "cache" {
+			// cache [ttl] [zones..]
+			origins = make([]string, len(c.ServerBlockKeys))
+			copy(origins, c.ServerBlockKeys)
+			args := c.RemainingArgs()
+			if len(args) > 0 {
+				origins = args
+				// first args may be just a number, then it is the ttl, if not it is a zone
+				t := origins[0]
+				ttl, err = strconv.Atoi(t)
+				if err == nil {
+					origins = origins[1:]
+					if len(origins) == 0 {
+						// There was *only* the ttl, revert back to server block
+						copy(origins, c.ServerBlockKeys)
+					}
+				}
+			}
+
+			for i, _ := range origins {
+				origins[i] = middleware.Host(origins[i]).Normalize()
+			}
+			return ttl, origins, nil
+		}
+	}
+	return 0, nil, nil
+}