Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

plugin/cache/setup.go

@@ -0,0 +1,170 @@
+package cache
+
+import (
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/pkg/cache"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("cache", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+}
+
+func setup(c *caddy.Controller) error {
+	ca, err := cacheParse(c)
+	if err != nil {
+		return plugin.Error("cache", err)
+	}
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		ca.Next = next
+		return ca
+	})
+
+	// Export the capacity for the metrics. This only happens once, because this is a re-load change only.
+	cacheCapacity.WithLabelValues(Success).Set(float64(ca.pcap))
+	cacheCapacity.WithLabelValues(Denial).Set(float64(ca.ncap))
+
+	return nil
+}
+
+func cacheParse(c *caddy.Controller) (*Cache, error) {
+
+	ca := &Cache{pcap: defaultCap, ncap: defaultCap, pttl: maxTTL, nttl: maxNTTL, prefetch: 0, duration: 1 * time.Minute}
+
+	for c.Next() {
+		// cache [ttl] [zones..]
+		origins := make([]string, len(c.ServerBlockKeys))
+		copy(origins, c.ServerBlockKeys)
+		args := c.RemainingArgs()
+
+		if len(args) > 0 {
+			// first args may be just a number, then it is the ttl, if not it is a zone
+			ttl, err := strconv.Atoi(args[0])
+			if err == nil {
+				// Reserve 0 (and smaller for future things)
+				if ttl <= 0 {
+					return nil, fmt.Errorf("cache TTL can not be zero or negative: %d", ttl)
+				}
+				ca.pttl = time.Duration(ttl) * time.Second
+				ca.nttl = time.Duration(ttl) * time.Second
+				args = args[1:]
+			}
+			if len(args) > 0 {
+				copy(origins, args)
+			}
+		}
+
+		// Refinements? In an extra block.
+		for c.NextBlock() {
+			switch c.Val() {
+			// first number is cap, second is an new ttl
+			case Success:
+				args := c.RemainingArgs()
+				if len(args) == 0 {
+					return nil, c.ArgErr()
+				}
+				pcap, err := strconv.Atoi(args[0])
+				if err != nil {
+					return nil, err
+				}
+				ca.pcap = pcap
+				if len(args) > 1 {
+					pttl, err := strconv.Atoi(args[1])
+					if err != nil {
+						return nil, err
+					}
+					// Reserve 0 (and smaller for future things)
+					if pttl <= 0 {
+						return nil, fmt.Errorf("cache TTL can not be zero or negative: %d", pttl)
+					}
+					ca.pttl = time.Duration(pttl) * time.Second
+				}
+			case Denial:
+				args := c.RemainingArgs()
+				if len(args) == 0 {
+					return nil, c.ArgErr()
+				}
+				ncap, err := strconv.Atoi(args[0])
+				if err != nil {
+					return nil, err
+				}
+				ca.ncap = ncap
+				if len(args) > 1 {
+					nttl, err := strconv.Atoi(args[1])
+					if err != nil {
+						return nil, err
+					}
+					// Reserve 0 (and smaller for future things)
+					if nttl <= 0 {
+						return nil, fmt.Errorf("cache TTL can not be zero or negative: %d", nttl)
+					}
+					ca.nttl = time.Duration(nttl) * time.Second
+				}
+			case "prefetch":
+				args := c.RemainingArgs()
+				if len(args) == 0 || len(args) > 3 {
+					return nil, c.ArgErr()
+				}
+				amount, err := strconv.Atoi(args[0])
+				if err != nil {
+					return nil, err
+				}
+				if amount < 0 {
+					return nil, fmt.Errorf("prefetch amount should be positive: %d", amount)
+				}
+				ca.prefetch = amount
+
+				ca.duration = 1 * time.Minute
+				ca.percentage = 10
+				if len(args) > 1 {
+					dur, err := time.ParseDuration(args[1])
+					if err != nil {
+						return nil, err
+					}
+					ca.duration = dur
+				}
+				if len(args) > 2 {
+					pct := args[2]
+					if x := pct[len(pct)-1]; x != '%' {
+						return nil, fmt.Errorf("last character of percentage should be `%%`, but is: %q", x)
+					}
+					pct = pct[:len(pct)-1]
+
+					num, err := strconv.Atoi(pct)
+					if err != nil {
+						return nil, err
+					}
+					if num < 10 || num > 90 {
+						return nil, fmt.Errorf("percentage should fall in range [10, 90]: %d", num)
+					}
+					ca.percentage = num
+				}
+
+			default:
+				return nil, c.ArgErr()
+			}
+		}
+
+		for i := range origins {
+			origins[i] = plugin.Host(origins[i]).Normalize()
+		}
+
+		ca.Zones = origins
+
+		ca.pcache = cache.New(ca.pcap)
+		ca.ncache = cache.New(ca.ncap)
+
+		return ca, nil
+	}
+
+	return nil, nil
+}