mw/kubernetes: add configurable TTL (#995)

* mw/kubernetes: add configurable TTL

Add ttl option to kubernetes. This defaults to 5s but allows
configuration to go up to 3600.

Configure the tests so that a few actually check for the 5s, while the
rest use the TTL of 303 which is ignored by the checking code.

Fixes #935

* fix tests

* and more

middleware/kubernetes/setup_ttl_test.go

@@ -0,0 +1,45 @@
+package kubernetes
+
+import (
+	"testing"
+
+	"github.com/mholt/caddy"
+)
+
+func TestKubernetesParseTTL(t *testing.T) {
+	tests := []struct {
+		input       string // Corefile data as string
+		expectedTTL uint32 // expected count of defined zones.
+		shouldErr   bool
+	}{
+		{`kubernetes cluster.local {
+			ttl 56
+		}`, 56, false},
+		{`kubernetes cluster.local`, defaultTTL, false},
+		{`kubernetes cluster.local {
+			ttl -1
+		}`, 0, true},
+		{`kubernetes cluster.local {
+			ttl 3601
+		}`, 0, true},
+	}
+
+	for i, tc := range tests {
+		c := caddy.NewTestController("dns", tc.input)
+		k, _, err := kubernetesParse(c)
+		if err != nil && !tc.shouldErr {
+			t.Fatalf("Test %d: Expected no error, got %q", i, err)
+		}
+		if err == nil && tc.shouldErr {
+			t.Fatalf("Test %d: Expected error, got none", i)
+		}
+		if err != nil && tc.shouldErr {
+			// input should error
+			continue
+		}
+
+		if k.ttl != tc.expectedTTL {
+			t.Errorf("Test %d: Expected TTl to be %d, got %d", i, tc.expectedTTL, k.ttl)
+		}
+	}
+}