New package defines .kubernetes_auth format.

Refactored common code to that package.
Subsequent PRs will load and emit these files.

pkg/clientauth/clientauth.go

@@ -0,0 +1,119 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/*
+Package authcfg defines a file format for holding authentication
+information needed by clients of Kubernetes.  Typically,
+a Kubernetes cluster will put auth info for the admin in a known
+location when it is created, and will (soon) put it in a known
+location within a Container's file tree for Containers that
+need access to the Kubernetes API.
+
+Having a defined format allows:
+  - clients to be implmented in multiple languages
+  - applications which link clients to be portable across
+    clusters with different authentication styles (e.g.
+    some may use SSL Client certs, others may not, etc)
+  - when the format changes, applications only
+    need to update this code.
+
+The file format is json, marshalled from a struct authcfg.Info.
+
+Clinet libraries in other languages should use the same format.
+
+It is not intended to store general preferences, such as default
+namespace, output options, etc.  CLIs (such as kubectl) and UIs should
+develop their own format and may wish to inline the authcfg.Info type.
+
+The authcfg.Info is just a file format.  It is distinct from
+client.Config which holds options for creating a client.Client.
+Helper functions are provided in this package to fill in a
+client.Client from an authcfg.Info.
+
+Example:
+
+    import (
+        "pkg/client"
+        "pkg/clientauth"
+    )
+
+    info, err := clientauth.LoadFromFile(filename)
+    if err != nil {
+      // handle error
+    }
+    clientConfig = client.Config{}
+    clientConfig.Host = "example.com:4901"
+    clientConfig = info.MergeWithConfig()
+    client := client.New(clientConfig)
+    client.ListPods()
+*/
+package clientauth
+
+// TODO: need a way to rotate Tokens.  Therefore, need a way for client object to be reset when the authcfg is updated.
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
+)
+
+// Info holds Kubernetes API authorization config.  It is intended
+// to be read/written from a file as a JSON object.
+type Info struct {
+	User        string
+	Password    string
+	CAFile      string
+	CertFile    string
+	KeyFile     string
+	BearerToken string
+	Insecure    *bool
+}
+
+// LoadFromFile parses an Info object from a file path.
+// If the file does not exist, then os.IsNotExist(err) == true
+func LoadFromFile(path string) (*Info, error) {
+	var info Info
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return nil, err
+	}
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	err = json.Unmarshal(data, &info)
+	if err != nil {
+		return nil, err
+	}
+	return &info, err
+}
+
+// MergeWithConfig returns a copy of a client.Config with values from the Info.
+// The fields of client.Config with a corresponding field in the Info are set
+// with the value from the Info.
+func (info Info) MergeWithConfig(c client.Config) (client.Config, error) {
+	var config client.Config = c
+	config.Username = info.User
+	config.Password = info.Password
+	config.CAFile = info.CAFile
+	config.CertFile = info.CertFile
+	config.KeyFile = info.KeyFile
+	config.BearerToken = info.BearerToken
+	if info.Insecure != nil {
+		config.Insecure = *info.Insecure
+	}
+	return config, nil
+}