k8s middleware cleanup, testcases, basic SRV (#181)

* Removing unnecessary gitignore pattern

* Updating Makefile to run unittests for subpackages

* Adding Corefile validation to ignore overlapping zones

* Fixing SRV query handling

* Updating README.md now that SRV works

* Fixing debug message, adding code comment

* Clarifying implementation of zone normalization

* "Overlapping zones" is ill-defined. Reimplemented zone overlap/subzone
  checking to contain these functions in k8s middleware and provide
  better code comments explaining the normalization.

* Separate build verbosity from test verbosity

* Cleaning up comments to match repo code style

* Merging warning messages into single message
* Moving function docs to before function declaration

* Adding test cases for k8sclient connector

* Tests cover connector create and setting base url
* Fixed bugs in connector create and setting base url functions

* Updaing README to group and order development work

* Priority focused on achieving functional parity with SkyDNS.

* Adding work items to README and cleaning up formatting

* More README format cleaning

* List formating

* Refactoring k8s API call to allow dependency injection

* Add test cases for data parsing from k8s into dataobject structures

* URL is dependency-injected to allow replacement with a mock http
  server during test execution

* Adding more data validation for JSON parsing tests

* Adding test case for GetResourceList()

* Adding notes about SkyDNS embedded IP and port record names

* Marked test case implemented.

* Fixing formatting for example command.

* Fixing formatting

* Adding notes about Docker image building.

* Adding SkyDNS work item

* Updating TODO list

* Adding name template to Corefile to specify how k8s record names are assembled

* Adding template support for multi-segment zones

* Updating example CoreFile for k8s with template comment

* Misc whitespace cleanup

* Adding SkyDNS naming notes

* Adding namespace filtering to CoreFile config

* Updating example k8sCoreFile to specify namespaces

* Removing unused codepath

* Adding check for valid namespace

* More README TODO restructuring to focus effort

* Adding template validation while parsing CoreFile

* Record name template is considered invalid if it contains a symbol of the form ${bar} where the symbol
  "${bar}" is not an accepted template symbol.

* Refactoring generation of answer records

* Parse typeName out of query string
* Refactor answer record creation as operation over list of ServiceItems

* Moving k8s API caching into SkyDNS equivalency segment

* Adding function to assemble record names from template

* Warning: This commit may be broken. Syncing to get laptop code over to dev machine.

* More todo notes

* Adding comment describing sample test data.

* Update k8sCorefile

* Adding comment

* Adding filtering support for kubernetes "type"

* Required refactoring to support reuse of the StringInSlice function.

* Cleaning up formatting

* Adding note about SkyDNS supporting word "any".

* baseUrl -> baseURL

* Also removed debug statement from core/setup/kubernetes.go

* Fixing test breaking from Url -> URL naming changes

* Changing record name template language ${...} -> {...}

* Fix formatting with go fmt

* Updating all k8sclient data getters to return error value

* Adding error message to k8sclient data accessors

* Cleaning up setup for kubernetes

* Removed verbose nils in initial k8s middleware instance
* Set reasonable defaults if CoreFile has no parameters in the
kubernetes block. (k8s endpoint, and name template)

* Formatting cleanup -- go fmt

1 files changed, 60 insertions, 57 deletions

diff --git a/middleware/kubernetes/k8sclient/dataobjects.go b/middleware/kubernetes/k8sclient/dataobjects.go
index a5ab4f19c..b17adeba4 100644
--- a/middleware/kubernetes/k8sclient/dataobjects.go
+++ b/middleware/kubernetes/k8sclient/dataobjects.go
@@ -1,110 +1,113 @@
 package k8sclient
 
 import (
-    "encoding/json"
-    "net/http"
+	"encoding/json"
+	"net/http"
 )
 
+// getK8sAPIResponse wraps the http.Get(url) function to provide dependency
+// injection for unit testing.
+var getK8sAPIResponse = func(url string) (resp *http.Response, err error) {
+	resp, err = http.Get(url)
+	return resp, err
+}
 
-func getJson(url string, target interface{}) error {
-    r, err := http.Get(url)
-    if err != nil {
-        return err
-    }
-    defer r.Body.Close()
+func parseJson(url string, target interface{}) error {
+	r, err := getK8sAPIResponse(url)
+	if err != nil {
+		return err
+	}
+	defer r.Body.Close()
 
-    return json.NewDecoder(r.Body).Decode(target)
+	return json.NewDecoder(r.Body).Decode(target)
 }
 
-
 // Kubernetes Resource List
 type ResourceList struct {
-    Kind         string `json:"kind"`
-    GroupVersion string `json:"groupVersion"`
-    Resources    []resource `json:"resources"`
+	Kind         string     `json:"kind"`
+	GroupVersion string     `json:"groupVersion"`
+	Resources    []resource `json:"resources"`
 }
 
 type resource struct {
-    Name         string `json:"name"`
-    Namespaced   bool   `json:"namespaced"`
-    Kind         string `json:"kind"`
+	Name       string `json:"name"`
+	Namespaced bool   `json:"namespaced"`
+	Kind       string `json:"kind"`
 }
 
-
 // Kubernetes NamespaceList
 type NamespaceList struct {
-    Kind         string          `json:"kind"`
-    APIVersion   string          `json:"apiVersion"`
-    Metadata     apiListMetadata  `json:"metadata"`
-    Items        []nsItems       `json:"items"`   
+	Kind       string          `json:"kind"`
+	APIVersion string          `json:"apiVersion"`
+	Metadata   apiListMetadata `json:"metadata"`
+	Items      []nsItems       `json:"items"`
 }
 
 type apiListMetadata struct {
-    SelfLink         string `json:"selfLink"`
-    resourceVersion  string `json:"resourceVersion"`
+	SelfLink        string `json:"selfLink"`
+	ResourceVersion string `json:"resourceVersion"`
 }
 
 type nsItems struct {
-    Metadata   nsMetadata  `json:"metadata"`
-    Spec       nsSpec      `json:"spec"`
-    Status     nsStatus    `json:"status"`
+	Metadata nsMetadata `json:"metadata"`
+	Spec     nsSpec     `json:"spec"`
+	Status   nsStatus   `json:"status"`
 }
 
 type nsMetadata struct {
-    Name              string  `json:"name"`
-    SelfLink          string  `json:"selfLink"`
-    Uid               string  `json:"uid"`
-    ResourceVersion   string  `json:"resourceVersion"`
-    CreationTimestamp string  `json:"creationTimestamp"`
+	Name              string `json:"name"`
+	SelfLink          string `json:"selfLink"`
+	Uid               string `json:"uid"`
+	ResourceVersion   string `json:"resourceVersion"`
+	CreationTimestamp string `json:"creationTimestamp"`
 }
 
 type nsSpec struct {
-    Finalizers []string `json:"finalizers"`
+	Finalizers []string `json:"finalizers"`
 }
 
 type nsStatus struct {
-    Phase string `json:"phase"`
+	Phase string `json:"phase"`
 }
 
-
 // Kubernetes ServiceList
 type ServiceList struct {
-    Kind         string          `json:"kind"`
-    APIVersion   string          `json:"apiVersion"`
-    Metadata     apiListMetadata  `json:"metadata"`
-    Items        []ServiceItem    `json:"items"`   
+	Kind       string          `json:"kind"`
+	APIVersion string          `json:"apiVersion"`
+	Metadata   apiListMetadata `json:"metadata"`
+	Items      []ServiceItem   `json:"items"`
 }
 
 type ServiceItem struct {
-    Metadata   serviceMetadata  `json:"metadata"`
-    Spec       serviceSpec      `json:"spec"`
-//    Status     serviceStatus    `json:"status"`
+	Metadata serviceMetadata `json:"metadata"`
+	Spec     serviceSpec     `json:"spec"`
+	//    Status     serviceStatus    `json:"status"`
 }
 
 type serviceMetadata struct {
-    Name              string  `json:"name"`
-    Namespace         string  `json:"namespace"`
-    SelfLink          string  `json:"selfLink"`
-    Uid               string  `json:"uid"`
-    ResourceVersion   string  `json:"resourceVersion"`
-    CreationTimestamp string  `json:"creationTimestamp"`
-    // labels
+	Name              string `json:"name"`
+	Namespace         string `json:"namespace"`
+	SelfLink          string `json:"selfLink"`
+	Uid               string `json:"uid"`
+	ResourceVersion   string `json:"resourceVersion"`
+	CreationTimestamp string `json:"creationTimestamp"`
+	// labels
 }
 
 type serviceSpec struct {
-    Ports           []servicePort `json:"ports"`
-    ClusterIP       string        `json:"clusterIP"`
-    Type            string        `json:"type"`
-    SessionAffinity string        `json:"sessionAffinity"`
+	Ports           []servicePort `json:"ports"`
+	ClusterIP       string        `json:"clusterIP"`
+	Type            string        `json:"type"`
+	SessionAffinity string        `json:"sessionAffinity"`
 }
 
 type servicePort struct {
-    Name            string        `json:"name"`
-    Protocol        string        `json:"protocol"`
-    Port            int           `json:"port"`
-    TargetPort      int           `json:"targetPort"`
+	Name       string `json:"name"`
+	Protocol   string `json:"protocol"`
+	Port       int    `json:"port"`
+	TargetPort int    `json:"targetPort"`
 }
 
 type serviceStatus struct {
-    LoadBalancer string `json:"loadBalancer"`
+	LoadBalancer string `json:"loadBalancer"`
 }