Init env metadata from provided context

`ks env add myenv --context=dev` will initialize the environment URI
and namespace based on the context `dev`, as specfied in the
kubeconfig file. The same applies for `ks init foo --context=dev`.

If both the context and uri argument is not provided, the current
context is used.

This change will also remove uri as a mandatory arg in `ks env add`.
The uri will be moved to a flag. It cannot be used at the same time as
`context`.

cmd/env.go

@@ -20,6 +20,7 @@ import (
 	"os"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
 
 	"github.com/ksonnet/ksonnet/metadata"
 	"github.com/ksonnet/ksonnet/pkg/kubecfg"
@@ -29,6 +30,7 @@ const (
 	flagEnvName      = "name"
 	flagEnvURI       = "uri"
 	flagEnvNamespace = "namespace"
+	flagEnvContext   = "context"
 )
 
 func init() {
@@ -45,6 +47,10 @@ func init() {
 		"Manually specify API version from OpenAPI schema, cluster, or Kubernetes version")
 	envAddCmd.PersistentFlags().String(flagEnvNamespace, "",
 		"Specify namespace that the environment cluster should use")
+	envAddCmd.PersistentFlags().String(flagEnvURI, "",
+		"Specify the server URI that the environment should use")
+	envAddCmd.PersistentFlags().String(flagEnvContext, "",
+		"Specify the context in your kubecfg file that this environment should use")
 
 	envSetCmd.PersistentFlags().String(flagEnvName, "",
 		"Specify name to rename environment to. Name must not already exist")
@@ -52,6 +58,8 @@ func init() {
 		"Specify URI to point environment cluster to a new location")
 	envSetCmd.PersistentFlags().String(flagEnvNamespace, "",
 		"Specify namespace that the environment cluster should use")
+	envSetCmd.PersistentFlags().String(flagEnvContext, "",
+		"Specify the context in your kubecfg file that this environment should use. This will update the server URI for your environment")
 }
 
 var envCmd = &cobra.Command{
@@ -95,22 +103,41 @@ environments/
 }
 
 var envAddCmd = &cobra.Command{
-	Use:   "add <env-name> <env-uri>",
+	Use:   "add <env-name>",
 	Short: "Add a new environment to a ksonnet project",
 	RunE: func(cmd *cobra.Command, args []string) error {
 		flags := cmd.Flags()
-		if len(args) != 2 {
-			return fmt.Errorf("'env add' takes two arguments, the name and the uri of the environment, respectively")
+		if len(args) != 1 {
+			return fmt.Errorf("'env add' takes exactly one argument, which is the name of the environment")
 		}
 
-		envName := args[0]
-		envURI := args[1]
+		name := args[0]
 
-		envNamespace, err := flags.GetString(flagEnvNamespace)
+		uri, namespace, context, err := commonEnvFlags(flags)
 		if err != nil {
 			return err
 		}
 
+		if len(uri) == 0 {
+			// If uri is not provided, use the provided context.
+			// If context is also not provided, use the current context.
+			var ctx *string
+			if len(context) != 0 {
+				ctx = &context
+			}
+
+			var ns string
+			uri, ns, err = resolveContext(ctx)
+			if err != nil {
+				return err
+			}
+
+			// If namespace is not provided, use the default namespace provided in the context.
+			if len(namespace) == 0 {
+				namespace = ns
+			}
+		}
+
 		appDir, err := os.Getwd()
 		if err != nil {
 			return err
@@ -127,7 +154,7 @@ var envAddCmd = &cobra.Command{
 			return err
 		}
 
-		c, err := kubecfg.NewEnvAddCmd(envName, envURI, envNamespace, specFlag, manager)
+		c, err := kubecfg.NewEnvAddCmd(name, uri, namespace, specFlag, manager)
 		if err != nil {
 			return err
 		}
@@ -164,17 +191,20 @@ environments/
         swagger.json
       spec.json      [This will contain the uri of the environment and other environment metadata],
       staging.jsonnet`,
-	Example: `  # Initialize a new staging environment at 'us-west'. Using the
-	# namespace 'my-namespace'. The directory structure rooted at 'us-west' in the
-	# documentation above will be generated.
-  ks env add us-west/staging https://ksonnet-1.us-west.elb.amazonaws.com --namespace=my-namespace
+	Example: `  # Initialize a new staging environment at 'us-west'.
+	# The environment will be setup using the current context in your kubecfg file. The directory
+	# structure rooted at 'us-west' in the documentation above will be generated.
+  ks env add us-west/staging
 
-  # Initialize a new staging environment at 'us-west', using the OpenAPI specification
-  # generated in the Kubernetes v1.7.1 build to generate 'ksonnet-lib'.
-  ks env add us-west/staging https://ksonnet-1.us-west.elb.amazonaws.com --api-spec=version:v1.7.1
+  # Initialize a new staging environment at 'us-west' with the namespace 'staging', using
+  # the OpenAPI specification generated in the Kubernetes v1.7.1 build to generate 'ksonnet-lib'.
+  ks env add us-west/staging --api-spec=version:v1.7.1 --namespace=staging
 
-  # Initialize a new development environment locally.
-  ks env add local localhost:8000`,
+  # Initialize a new environment using the 'dev' context in your kubeconfig file.
+  ks env add my-env --context=dev
+
+  # Initialize a new environment using a server URI.
+  ks env add my-env --uri=https://ksonnet-1.us-west.elb.amazonaws.com`,
 }
 
 var envRmCmd = &cobra.Command{
@@ -255,7 +285,7 @@ var envSetCmd = &cobra.Command{
 			return fmt.Errorf("'env set' takes a single argument, that is the name of the environment")
 		}
 
-		envName := args[0]
+		originalName := args[0]
 
 		appDir, err := os.Getwd()
 		if err != nil {
@@ -268,22 +298,24 @@ var envSetCmd = &cobra.Command{
 			return err
 		}
 
-		desiredEnvName, err := flags.GetString(flagEnvName)
+		name, err := flags.GetString(flagEnvName)
 		if err != nil {
 			return err
 		}
 
-		desiredEnvURI, err := flags.GetString(flagEnvURI)
+		uri, namespace, context, err := commonEnvFlags(flags)
 		if err != nil {
 			return err
 		}
 
-		desiredEnvNamespace, err := flags.GetString(flagEnvNamespace)
-		if err != nil {
-			return err
+		if len(context) != 0 {
+			uri, _, err = resolveContext(&context)
+			if err != nil {
+				return err
+			}
 		}
 
-		c, err := kubecfg.NewEnvSetCmd(envName, desiredEnvName, desiredEnvURI, desiredEnvNamespace, manager)
+		c, err := kubecfg.NewEnvSetCmd(originalName, name, uri, namespace, manager)
 		if err != nil {
 			return err
 		}
@@ -300,6 +332,34 @@ the name of an environment will also update the directory structure in
   ks env set us-west/staging --namespace=staging
 
   # Updates both the name and the URI of the environment 'us-west/staging'.
-  # Updating the name will update the directory structure in 'environments'
-  ks env set us-west/staging --uri=http://example.com --name=us-east/staging`,
+  # Updating the name will update the directory structure in 'environments'.
+  ks env set us-west/staging --uri=http://example.com --name=us-east/staging
+  
+  # Updates URI of the environment 'us-west/staging' based on the server URI
+  # in the context 'staging-west' in your kubeconfig file.
+  ks env set us-west/staging --context=staging-west`,
+}
+
+func commonEnvFlags(flags *pflag.FlagSet) (uri, namespace, context string, err error) {
+	uri, err = flags.GetString(flagEnvURI)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	namespace, err = flags.GetString(flagEnvNamespace)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	context, err = flags.GetString(flagEnvContext)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	if len(context) != 0 && len(uri) != 0 {
+		return "", "", "", fmt.Errorf("flags '%s' and '%s' are mutually exclusive, because '%s' has a URI. Try setting '%s', '%s' to the desired values",
+			flagEnvContext, flagEnvURI, flagEnvContext, flagEnvURI, flagEnvNamespace)
+	}
+
+	return uri, namespace, context, nil
 }

cmd/init.go

@@ -20,8 +20,6 @@ import (
 	"os"
 	"path"
 
-	"k8s.io/client-go/tools/clientcmd/api"
-
 	"github.com/ksonnet/ksonnet/metadata"
 	"github.com/ksonnet/ksonnet/pkg/kubecfg"
 	"github.com/spf13/cobra"
@@ -57,32 +55,22 @@ var initCmd = &cobra.Command{
 			return err
 		}
 
-		//
-		// Find the URI of the current cluster, if it exists.
-		//
-
-		rawConfig, err := clientConfig.RawConfig()
+		context, err := flags.GetString(flagEnvContext)
 		if err != nil {
 			return err
 		}
 
-		var currCtx *api.Context
-		for name, ctx := range rawConfig.Contexts {
-			if name == rawConfig.CurrentContext {
-				currCtx = ctx
-			}
+		// Find the URI and namespace of the current cluster, if it exists.
+		var ctx *string
+		if len(context) != 0 {
+			ctx = &context
 		}
-
-		var currClusterURI *string
-		if rawConfig.CurrentContext != "" && currCtx != nil {
-			for name, cluster := range rawConfig.Clusters {
-				if currCtx.Cluster == name {
-					currClusterURI = &cluster.Server
-				}
-			}
+		uri, namespace, err := resolveContext(ctx)
+		if err != nil {
+			return err
 		}
 
-		c, err := kubecfg.NewInitCmd(appRoot, specFlag, currClusterURI, &currCtx.Namespace)
+		c, err := kubecfg.NewInitCmd(appRoot, specFlag, &uri, &namespace)
 		if err != nil {
 			return err
 		}
@@ -123,5 +111,9 @@ consists of two steps:
 
   # Initialize ksonnet application, using an OpenAPI specification file
   # generated by a build of Kubernetes to generate 'ksonnet-lib'.
-  ks init app-name --api-spec=file:swagger.json`,
+  ks init app-name --api-spec=file:swagger.json
+  
+  # Initialize ksonnet application, using the context 'dev' from the kubeconfig
+  # file.
+  ks init app-name --context=dev`,
 }

cmd/root.go

@@ -128,6 +128,28 @@ func namespace() (string, error) {
 	return ns, err
 }
 
+// resolveContext returns the server URI and namespace of the cluster at the provided
+// context. If context is nil, the current context is used.
+func resolveContext(context *string) (uri, namespace string, err error) {
+	rawConfig, err := clientConfig.RawConfig()
+	if err != nil {
+		return "", "", err
+	}
+
+	ctxName := rawConfig.CurrentContext
+	if context != nil {
+		ctxName = *context
+	}
+	ctx := rawConfig.Contexts[ctxName]
+	if ctx == nil {
+		return "", "", fmt.Errorf("context '%s' does not exist in the kubeconfig file", *context)
+	}
+
+	log.Infof("Using context '%s'", ctxName)
+	cluster := rawConfig.Clusters[ctx.Cluster]
+	return cluster.Server, ctx.Namespace, nil
+}
+
 func logLevel(verbosity int) log.Level {
 	switch verbosity {
 	case 0: