Add createKubeconfigFile()

Refactoring. Make createKubeconfigFile() a stand along function, so we
don't have to recreate the file every time we look up the file name.

cli/cluster.go

@@ -1,8 +1,10 @@
 package run
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
 	"path"
@@ -90,6 +92,62 @@ func getClusterKubeConfigPath(cluster string) (string, error) {
 	return path.Join(clusterDir, "kubeconfig.yaml"), err
 }
 
+func createKubeConfigFile(cluster string) error {
+	ctx := context.Background()
+	docker, err := client.NewEnvClient()
+	if err != nil {
+		return err
+	}
+
+	filters := filters.NewArgs()
+	filters.Add("label", "app=k3d")
+	filters.Add("label", fmt.Sprintf("cluster=%s", cluster))
+	filters.Add("label", "component=server")
+	server, err := docker.ContainerList(ctx, types.ContainerListOptions{
+		Filters: filters,
+	})
+
+	if err != nil {
+		return fmt.Errorf("Failed to get server container for cluster %s\n%+v", cluster, err)
+	}
+
+	if len(server) == 0 {
+		return fmt.Errorf("No server container for cluster %s", cluster)
+	}
+
+	// get kubeconfig file from container and read contents
+	reader, _, err := docker.CopyFromContainer(ctx, server[0].ID, "/output/kubeconfig.yaml")
+	if err != nil {
+		return fmt.Errorf("ERROR: couldn't copy kubeconfig.yaml from server container %s\n%+v", server[0].ID, err)
+	}
+	defer reader.Close()
+
+	readBytes, err := ioutil.ReadAll(reader)
+	if err != nil {
+		return fmt.Errorf("ERROR: couldn't read kubeconfig from container\n%+v", err)
+	}
+
+	// create destination kubeconfig file
+	destPath, err := getClusterKubeConfigPath(cluster)
+	if err != nil {
+		return err
+	}
+
+	kubeconfigfile, err := os.Create(destPath)
+	if err != nil {
+		return fmt.Errorf("ERROR: couldn't create kubeconfig file %s\n%+v", destPath, err)
+	}
+	defer kubeconfigfile.Close()
+
+	// write to file, skipping the first 512 bytes which contain file metadata and trimming any NULL characters
+	_, err = kubeconfigfile.Write(bytes.Trim(readBytes[512:], "\x00"))
+	if err != nil {
+		return fmt.Errorf("ERROR: couldn't write to kubeconfig.yaml\n%+v", err)
+	}
+
+	return nil
+}
+
 // printClusters prints the names of existing clusters
 func printClusters() {
 	clusters, err := getClusters(true, "")

cli/commands.go

@@ -9,15 +9,12 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/docker/docker/api/types/filters"
-
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/client"
 	"github.com/urfave/cli"
@@ -346,60 +343,29 @@ func ListClusters(c *cli.Context) error {
 
 // GetKubeConfig grabs the kubeconfig from the running cluster and prints the path to stdout
 func GetKubeConfig(c *cli.Context) error {
-	ctx := context.Background()
-	docker, err := client.NewEnvClient()
-	if err != nil {
-		return err
-	}
-
-	filters := filters.NewArgs()
-	filters.Add("label", "app=k3d")
-	filters.Add("label", fmt.Sprintf("cluster=%s", c.String("name")))
-	filters.Add("label", "component=server")
-	server, err := docker.ContainerList(ctx, types.ContainerListOptions{
-		Filters: filters,
-	})
-
-	if err != nil {
-		return fmt.Errorf("Failed to get server container for cluster %s\n%+v", c.String("name"), err)
-	}
-
-	if len(server) == 0 {
-		return fmt.Errorf("No server container for cluster %s", c.String("name"))
-	}
-
-	// get kubeconfig file from container and read contents
-	reader, _, err := docker.CopyFromContainer(ctx, server[0].ID, "/output/kubeconfig.yaml")
-	if err != nil {
-		return fmt.Errorf("ERROR: couldn't copy kubeconfig.yaml from server container %s\n%+v", server[0].ID, err)
-	}
-	defer reader.Close()
-
-	readBytes, err := ioutil.ReadAll(reader)
-	if err != nil {
-		return fmt.Errorf("ERROR: couldn't read kubeconfig from container\n%+v", err)
-	}
-
-	// create destination kubeconfig file
+	cluster := c.String("name")
 	destPath, err := getClusterKubeConfigPath(c.String("name"))
 	if err != nil {
 		return err
 	}
 
-	kubeconfigfile, err := os.Create(destPath)
-	if err != nil {
-		return fmt.Errorf("ERROR: couldn't create kubeconfig file %s\n%+v", destPath, err)
+	if clusters, err := getClusters(false, cluster); err != nil || len(clusters) != 1 {
+		if err != nil {
+			return err
+		}
+		return fmt.Errorf("Cluster %s does not exist", cluster)
 	}
-	defer kubeconfigfile.Close()
 
-	// write to file, skipping the first 512 bytes which contain file metadata and trimming any NULL characters
-	_, err = kubeconfigfile.Write(bytes.Trim(readBytes[512:], "\x00"))
-	if err != nil {
-		return fmt.Errorf("ERROR: couldn't write to kubeconfig.yaml\n%+v", err)
+	// If kubeconfig.yaml has not been created, generate it now.
+	if _, err := os.Stat(destPath); os.IsNotExist(err) {
+		if err = createKubeConfigFile(cluster); err != nil {
+			return err
+		}
+	} else {
+		return err
 	}
 
 	// output kubeconfig file path to stdout
 	fmt.Println(destPath)
-
 	return nil
 }