Update README.md, go.mod, and resolver.go

resolver/README.md

@@ -0,0 +1,67 @@
+## Installation
+To be able to import this package, you must add `replace github.com/up9inc/mizu/resolver => ../resolver` to the end of your `go.mod` file 
+
+And then add `github.com/up9inc/mizu/resolver v0.0.0` to your require block
+
+full example `go.mod`:
+
+```
+module github.com/up9inc/mizu/cli
+
+go 1.16
+
+require (
+	github.com/spf13/cobra v1.1.3
+	github.com/up9inc/mizu/resolver v0.0.0
+	k8s.io/api v0.21.0
+	k8s.io/apimachinery v0.21.0
+	k8s.io/client-go v0.21.0
+)
+
+replace github.com/up9inc/mizu/resolver => ../resolver
+```
+
+Now you will be able to import `github.com/up9inc/mizu/resolver` in any `.go` file
+
+## Usage
+
+### Full example
+``` go
+errOut := make(chan error, 100)
+k8sResolver, err := resolver.NewFromOutOfCluster("", errOut)
+if err != nil {
+    fmt.Printf("error creating k8s resolver %s", err)
+}
+
+ctx, cancel := context.WithCancel(context.Background())
+k8sResolver.Start(ctx)
+
+resolvedName := k8sResolver.Resolve("10.107.251.91") // will always return `nil` in real scenarios as the internal map takes a moment to populate after `Start` is called
+if resolvedName != nil {
+    fmt.Printf("resolved 10.107.251.91=%s", *resolvedName)
+} else {
+    fmt.Printf("Could not find a resolved name for 10.107.251.91")
+}
+
+for {
+    select {
+        case err := <- errOut:
+            fmt.Printf("name resolving error %s", err)
+    }
+}
+```
+
+### In cluster
+use the function `NewFromInCluster(errOut chan error)`
+
+### Out of cluster
+use the function `NewFromOutOfCluster(kubeConfigPath string, errOut chan error)`
+
+the `kubeConfigPath` param is optional, pass an empty string `""` for resolver to auto locate the default kubeconfig file
+
+### Error handling
+Please ensure there is always a thread reading from the `errOut` channel, not doing so will result in the resolver threads getting blocked and the resolver will fail to update.
+
+Also note that any error you receive through this channel does not necessarily mean that resolver is no longer running. the resolver will infinitely retry watching k8s resources.
+
+

resolver/go.mod

@@ -1,4 +1,4 @@
-module github.com/up9inc/k8s-resolver
+module github.com/up9inc/mizu/resolver
 
 go 1.16
 

resolver/resolver.go

@@ -32,6 +32,14 @@ func (resolver *Resolver) Start(ctx context.Context) {
 	}
 }
 
+func (resolver *Resolver) Resolve(name string) *string {
+	resolvedName, isFound := resolver.nameMap[name]
+	if !isFound {
+		return nil
+	}
+	return &resolvedName
+}
+
 func (resolver *Resolver) watchPods(ctx context.Context) error {
 	// empty namespace makes the client watch all namespaces
 	watcher, err := resolver.clientSet.CoreV1().Pods("").Watch(ctx, metav1.ListOptions{Watch: true})
@@ -131,10 +139,10 @@ func (resolver *Resolver) watchServices(ctx context.Context) error {
 func (resolver *Resolver) saveResolvedName(key string, resolved string, eventType watch.EventType) {
 	if eventType == watch.Deleted {
 		delete(resolver.nameMap, key)
-		fmt.Printf("setting %s=nil\n", key)
+		// fmt.Printf("setting %s=nil\n", key)
 	} else {
 		resolver.nameMap[key] = resolved
-		fmt.Printf("setting %s=%s\n", key, resolved)
+		// fmt.Printf("setting %s=%s\n", key, resolved)
 	}
 }