Simplified bootstrapping of a cluster (#40)

* Simplified bootstrapping of a cluster

Introduced a new convention about a pre-defined `bootstrap-admin` account for `orchard controller run`. Providing `ORCHARD_BOOTSTRAP_ADMIN_TOKEN` will auto-create such user for easier configuration. `bootstrap-admin` can be used for creating other service accounts on the first run and after that can be disposed.

Also change `orchard worker run` to expect controller URL as the only parameter and a bootstrap token passed via an argument instead of using a context that might not be created.

* Missing error check

internal/command/worker/run.go

@@ -1,19 +1,52 @@
 package worker
 
 import (
+	"errors"
+	"github.com/cirruslabs/orchard/internal/bootstraptoken"
+	"github.com/cirruslabs/orchard/internal/netconstants"
 	"github.com/cirruslabs/orchard/internal/worker"
+	"github.com/cirruslabs/orchard/pkg/client"
 	"github.com/spf13/cobra"
 	"go.uber.org/zap"
 )
 
+var ErrBootstrapTokenNotProvided = errors.New("no bootstrap token provided")
+
+var bootstrapTokenRaw string
+
 func newRunCommand() *cobra.Command {
-	return &cobra.Command{
+	cmd := &cobra.Command{
 		Use:  "run",
 		RunE: runWorker,
+		Args: cobra.ExactArgs(1),
 	}
+	cmd.PersistentFlags().StringVar(&bootstrapTokenRaw, "bootstrap-token", "",
+		"a bootstrap token retrieved via `orchard get bootstrap-token <service-account-name-for-workers>`")
+	return cmd
 }
 
 func runWorker(cmd *cobra.Command, args []string) (err error) {
+	controllerURL, err := netconstants.NormalizeAddress(args[0])
+	if err != nil {
+		return err
+	}
+	if bootstrapTokenRaw == "" {
+		return ErrBootstrapTokenNotProvided
+	}
+	bootstrapToken, err := bootstraptoken.NewFromString(bootstrapTokenRaw)
+	if err != nil {
+		return err
+	}
+
+	controllerClient, err := client.New(
+		client.WithAddress(controllerURL.String()),
+		client.WithTrustedCertificate(bootstrapToken.Certificate()),
+		client.WithCredentials(bootstrapToken.ServiceAccountName(), bootstrapToken.ServiceAccountToken()),
+	)
+	if err != nil {
+		return err
+	}
+
 	// Initialize the logger
 	logger, err := zap.NewProduction()
 	if err != nil {
@@ -25,10 +58,10 @@ func runWorker(cmd *cobra.Command, args []string) (err error) {
 		}
 	}()
 
-	worker, err := worker.New(worker.WithDataDirPath(dataDirPath), worker.WithLogger(logger))
+	workerInstance, err := worker.New(worker.WithClient(controllerClient), worker.WithLogger(logger))
 	if err != nil {
 		return err
 	}
 
-	return worker.Run(cmd.Context())
+	return workerInstance.Run(cmd.Context())
 }