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.

middleware/errors/setup_test.go

@@ -0,0 +1,98 @@
+package errors
+
+import (
+	"testing"
+
+	"github.com/mholt/caddy"
+	"github.com/miekg/coredns/middleware"
+)
+
+func TestErrorsParse(t *testing.T) {
+	tests := []struct {
+		inputErrorsRules     string
+		shouldErr            bool
+		expectedErrorHandler ErrorHandler
+	}{
+		{`errors`, false, ErrorHandler{
+			LogFile: "",
+		}},
+		{`errors errors.txt`, false, ErrorHandler{
+			LogFile: "errors.txt",
+		}},
+		{`errors visible`, false, ErrorHandler{
+			LogFile: "",
+			Debug:   true,
+		}},
+		{`errors { log visible }`, false, ErrorHandler{
+			LogFile: "",
+			Debug:   true,
+		}},
+		{`errors { log errors.txt { size 2 age 10 keep 3 } }`, false, ErrorHandler{
+			LogFile: "errors.txt",
+			LogRoller: &middleware.LogRoller{
+				MaxSize:    2,
+				MaxAge:     10,
+				MaxBackups: 3,
+				LocalTime:  true,
+			},
+		}},
+		{`errors { log errors.txt {
+            size 3
+            age 11
+            keep 5
+        }
+}`, false, ErrorHandler{
+			LogFile: "errors.txt",
+			LogRoller: &middleware.LogRoller{
+				MaxSize:    3,
+				MaxAge:     11,
+				MaxBackups: 5,
+				LocalTime:  true,
+			},
+		}},
+	}
+	for i, test := range tests {
+		c := caddy.NewTestController("dns", test.inputErrorsRules)
+		actualErrorsRule, err := errorsParse(c)
+
+		if err == nil && test.shouldErr {
+			t.Errorf("Test %d didn't error, but it should have", i)
+		} else if err != nil && !test.shouldErr {
+			t.Errorf("Test %d errored, but it shouldn't have; got '%v'", i, err)
+		}
+		if actualErrorsRule.LogFile != test.expectedErrorHandler.LogFile {
+			t.Errorf("Test %d expected LogFile to be %s, but got %s",
+				i, test.expectedErrorHandler.LogFile, actualErrorsRule.LogFile)
+		}
+		if actualErrorsRule.Debug != test.expectedErrorHandler.Debug {
+			t.Errorf("Test %d expected Debug to be %v, but got %v",
+				i, test.expectedErrorHandler.Debug, actualErrorsRule.Debug)
+		}
+		if actualErrorsRule.LogRoller != nil && test.expectedErrorHandler.LogRoller == nil || actualErrorsRule.LogRoller == nil && test.expectedErrorHandler.LogRoller != nil {
+			t.Fatalf("Test %d expected LogRoller to be %v, but got %v",
+				i, test.expectedErrorHandler.LogRoller, actualErrorsRule.LogRoller)
+		}
+		if actualErrorsRule.LogRoller != nil && test.expectedErrorHandler.LogRoller != nil {
+			if actualErrorsRule.LogRoller.Filename != test.expectedErrorHandler.LogRoller.Filename {
+				t.Fatalf("Test %d expected LogRoller Filename to be %s, but got %s",
+					i, test.expectedErrorHandler.LogRoller.Filename, actualErrorsRule.LogRoller.Filename)
+			}
+			if actualErrorsRule.LogRoller.MaxAge != test.expectedErrorHandler.LogRoller.MaxAge {
+				t.Fatalf("Test %d expected LogRoller MaxAge to be %d, but got %d",
+					i, test.expectedErrorHandler.LogRoller.MaxAge, actualErrorsRule.LogRoller.MaxAge)
+			}
+			if actualErrorsRule.LogRoller.MaxBackups != test.expectedErrorHandler.LogRoller.MaxBackups {
+				t.Fatalf("Test %d expected LogRoller MaxBackups to be %d, but got %d",
+					i, test.expectedErrorHandler.LogRoller.MaxBackups, actualErrorsRule.LogRoller.MaxBackups)
+			}
+			if actualErrorsRule.LogRoller.MaxSize != test.expectedErrorHandler.LogRoller.MaxSize {
+				t.Fatalf("Test %d expected LogRoller MaxSize to be %d, but got %d",
+					i, test.expectedErrorHandler.LogRoller.MaxSize, actualErrorsRule.LogRoller.MaxSize)
+			}
+			if actualErrorsRule.LogRoller.LocalTime != test.expectedErrorHandler.LogRoller.LocalTime {
+				t.Fatalf("Test %d expected LogRoller LocalTime to be %t, but got %t",
+					i, test.expectedErrorHandler.LogRoller.LocalTime, actualErrorsRule.LogRoller.LocalTime)
+			}
+		}
+	}
+}