Standardize use of templates (#353)

Signed-off-by: David Chung <david.chung@docker.com>

Author: David Chung

cmd/cli/main.go

@@ -39,6 +39,8 @@ func main() {
 	}
 
 	cmd.AddCommand(cli.VersionCommand(), cli.InfoCommand(f))
+
+	cmd.AddCommand(templateCommand(f))
 	cmd.AddCommand(pluginCommand(f), instancePluginCommand(f), groupPluginCommand(f), flavorPluginCommand(f))
 
 	err := cmd.Execute()

cmd/cli/template.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/docker/infrakit/pkg/discovery"
+	"github.com/docker/infrakit/pkg/template"
+	"github.com/spf13/cobra"
+)
+
+func templateCommand(plugins func() discovery.Plugins) *cobra.Command {
+
+	templateURL := ""
+	cmd := &cobra.Command{
+		Use:   "template",
+		Short: "Render an infrakit template",
+		RunE: func(cmd *cobra.Command, args []string) error {
+
+			log.Infof("Using %v for reading template\n", templateURL)
+			engine, err := template.NewTemplate(templateURL, template.Options{
+				SocketDir: discovery.Dir(),
+			})
+			if err != nil {
+				return err
+			}
+			view, err := engine.Render(nil)
+			if err != nil {
+				return err
+			}
+
+			fmt.Print(view)
+			return nil
+		},
+	}
+	cmd.Flags().StringVar(&templateURL, "url", "", "URL for the template")
+
+	return cmd
+}

pkg/example/flavor/swarm/flavor.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+
 	log "github.com/Sirupsen/logrus"
 	docker_types "github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/filters"
@@ -13,8 +14,8 @@ import (
 	"github.com/docker/infrakit/pkg/plugin/group/util"
 	"github.com/docker/infrakit/pkg/spi/flavor"
 	"github.com/docker/infrakit/pkg/spi/instance"
+	"github.com/docker/infrakit/pkg/template"
 	"golang.org/x/net/context"
-	"text/template"
 )
 
 type nodeType string
@@ -26,12 +27,13 @@ const (
 )
 
 // NewSwarmFlavor creates a flavor.Plugin that creates manager and worker nodes connected in a swarm.
-func NewSwarmFlavor(dockerClient client.APIClient) flavor.Plugin {
-	return &swarmFlavor{client: dockerClient}
+func NewSwarmFlavor(dockerClient client.APIClient, templ *template.Template) flavor.Plugin {
+	return &swarmFlavor{client: dockerClient, initScript: templ}
 }
 
 type swarmFlavor struct {
-	client client.APIClient
+	client     client.APIClient
+	initScript *template.Template
 }
 
 type schema struct {
@@ -135,39 +137,20 @@ func (s swarmFlavor) Validate(flavorProperties json.RawMessage, allocation types
 const (
 	// associationTag is a machine tag added to associate machines with Swarm nodes.
 	associationTag = "swarm-association-id"
-
-	// bootScript is used to generate node boot scripts.
-	bootScript = `#!/bin/sh
-set -o errexit
-set -o nounset
-set -o xtrace
-
-mkdir -p /etc/docker
-cat << EOF > /etc/docker/daemon.json
-{
-  "labels": ["swarm-association-id={{.ASSOCIATION_ID}}"]
-}
-EOF
-
-{{.RESTART_DOCKER}}
-
-docker swarm join {{.MY_IP}} --token {{.JOIN_TOKEN}}
-`
 )
 
-func generateInitScript(joinIP, joinToken, associationID, restartCommand string) string {
-	buffer := bytes.Buffer{}
-	templ := template.Must(template.New("").Parse(bootScript))
+func generateInitScript(templ *template.Template, joinIP, joinToken, associationID, restartCommand string) (string, error) {
+	var buffer bytes.Buffer
 	err := templ.Execute(&buffer, map[string]string{
 		"MY_IP":          joinIP,
 		"JOIN_TOKEN":     joinToken,
 		"ASSOCIATION_ID": associationID,
 		"RESTART_DOCKER": restartCommand,
 	})
 	if err != nil {
-		panic(err)
+		return "", err
 	}
-	return buffer.String()
+	return buffer.String(), nil
 }
 
 // Healthy determines whether an instance is healthy.  This is determined by whether it has successfully joined the
@@ -246,7 +229,7 @@ func (s swarmFlavor) Drain(flavorProperties json.RawMessage, inst instance.Descr
 	}
 }
 
-func (s swarmFlavor) Prepare(
+func (s *swarmFlavor) Prepare(
 	flavorProperties json.RawMessage,
 	spec instance.Spec,
 	allocation types.AllocationMethod) (instance.Spec, error) {
@@ -281,24 +264,34 @@ func (s swarmFlavor) Prepare(
 
 	switch properties.Type {
 	case worker:
-		spec.Init = generateInitScript(
-			self.ManagerStatus.Addr,
-			swarmStatus.JoinTokens.Worker,
-			associationID,
-			properties.DockerRestartCommand)
+		initScript, err :=
+			generateInitScript(
+				s.initScript,
+				self.ManagerStatus.Addr,
+				swarmStatus.JoinTokens.Worker,
+				associationID,
+				properties.DockerRestartCommand)
+		if err != nil {
+			return spec, err
+		}
+		spec.Init = initScript
 
 	case manager:
 		if spec.LogicalID == nil {
 			return spec, errors.New("Manager nodes require a LogicalID, " +
 				"which will be used as an assigned private IP address")
 		}
 
-		spec.Init = generateInitScript(
+		initScript, err := generateInitScript(
+			s.initScript,
 			self.ManagerStatus.Addr,
 			swarmStatus.JoinTokens.Manager,
 			associationID,
 			properties.DockerRestartCommand)
-
+		if err != nil {
+			return spec, err
+		}
+		spec.Init = initScript
 	default:
 		return spec, errors.New("Unsupported node type")
 	}

pkg/example/flavor/swarm/flavor_test.go

@@ -3,23 +3,33 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"testing"
+
 	docker_types "github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/filters"
 	"github.com/docker/docker/api/types/swarm"
 	mock_client "github.com/docker/infrakit/pkg/mock/docker/docker/client"
 	"github.com/docker/infrakit/pkg/plugin/group/types"
 	"github.com/docker/infrakit/pkg/spi/flavor"
 	"github.com/docker/infrakit/pkg/spi/instance"
+	"github.com/docker/infrakit/pkg/template"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/require"
-	"testing"
 )
 
+func templ() *template.Template {
+	t, err := template.NewTemplate("str://"+DefaultInitScriptTemplate, template.Options{})
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+
 func TestValidate(t *testing.T) {
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 
-	swarmFlavor := NewSwarmFlavor(mock_client.NewMockAPIClient(ctrl))
+	swarmFlavor := NewSwarmFlavor(mock_client.NewMockAPIClient(ctrl), templ())
 
 	require.NoError(t, swarmFlavor.Validate(
 		json.RawMessage(`{"Type": "worker", "DockerRestartCommand": "systemctl restart docker"}`),
@@ -72,7 +82,7 @@ func TestWorker(t *testing.T) {
 
 	client := mock_client.NewMockAPIClient(ctrl)
 
-	flavorImpl := NewSwarmFlavor(client)
+	flavorImpl := NewSwarmFlavor(client, templ())
 
 	swarmInfo := swarm.Swarm{
 		ClusterInfo: swarm.ClusterInfo{ID: "ClusterUUID"},
@@ -134,7 +144,7 @@ func TestManager(t *testing.T) {
 
 	client := mock_client.NewMockAPIClient(ctrl)
 
-	flavorImpl := NewSwarmFlavor(client)
+	flavorImpl := NewSwarmFlavor(client, templ())
 
 	swarmInfo := swarm.Swarm{
 		ClusterInfo: swarm.ClusterInfo{ID: "ClusterUUID"},

pkg/example/flavor/swarm/main.go

@@ -6,7 +6,9 @@ import (
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/go-connections/tlsconfig"
 	"github.com/docker/infrakit/pkg/cli"
+	"github.com/docker/infrakit/pkg/discovery"
 	flavor_plugin "github.com/docker/infrakit/pkg/rpc/flavor"
+	"github.com/docker/infrakit/pkg/template"
 	"github.com/docker/infrakit/pkg/util/docker"
 	"github.com/spf13/cobra"
 )
@@ -31,6 +33,8 @@ func main() {
 	certFile := cmd.Flags().String("tlscert", "", "TLS cert file path")
 	tlsKey := cmd.Flags().String("tlskey", "", "TLS key file path")
 	insecureSkipVerify := cmd.Flags().Bool("tlsverify", true, "True to skip TLS")
+	initScriptTemplURL := cmd.Flags().String("init-template", "", "Init script template file, in URL form")
+
 	cmd.RunE = func(c *cobra.Command, args []string) error {
 
 		cli.SetLogLevel(*logLevel)
@@ -46,7 +50,27 @@ func main() {
 			return err
 		}
 
-		cli.RunPlugin(*name, flavor_plugin.PluginServer(NewSwarmFlavor(dockerClient)))
+		opts := template.Options{
+			SocketDir: discovery.Dir(),
+		}
+
+		var templ *template.Template
+		if *initScriptTemplURL == "" {
+			t, err := template.NewTemplate("str://"+DefaultInitScriptTemplate, opts)
+			if err != nil {
+				return err
+			}
+			templ = t
+		} else {
+
+			t, err := template.NewTemplate(*initScriptTemplURL, opts)
+			if err != nil {
+				return err
+			}
+			templ = t
+		}
+
+		cli.RunPlugin(*name, flavor_plugin.PluginServer(NewSwarmFlavor(dockerClient, templ)))
 		return nil
 	}
 
@@ -58,3 +82,25 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+const (
+	// DefaultInitScriptTemplate is the default template for the init script which
+	// the flavor injects into the user data of the instance to configure Docker Swarm.
+	DefaultInitScriptTemplate = `
+#!/bin/sh
+set -o errexit
+set -o nounset
+set -o xtrace
+
+mkdir -p /etc/docker
+cat << EOF > /etc/docker/daemon.json
+{
+  "labels": ["swarm-association-id={{.ASSOCIATION_ID}}"]
+}
+EOF
+
+{{.RESTART_DOCKER}}
+
+docker swarm join {{.MY_IP}} --token {{.JOIN_TOKEN}}
+`
+)

pkg/example/flavor/swarm/swarm-vagrant-manager.json

@@ -2,7 +2,7 @@
   "ID": "swarm-managers",
   "Properties": {
     "Allocation": {
-      "LogicalIDs": ["192.168.2.200"]
+	"LogicalIDs": ["192.168.2.200"]
     },
     "Instance": {
       "Plugin": "instance-vagrant",

pkg/example/flavor/swarm/swarm-vagrant-workers.json

@@ -2,7 +2,7 @@
   "ID": "swarm-workers",
   "Properties": {
     "Allocation": {
-      "Size": 1
+      "Size": 2
     },
     "Instance": {
       "Plugin": "instance-vagrant",

pkg/example/instance/vagrant/instance.go

@@ -9,9 +9,9 @@ import (
 	"os"
 	"os/exec"
 	"path"
-	"text/template"
 
 	"github.com/docker/infrakit/pkg/spi/instance"
+	"github.com/docker/infrakit/pkg/template"
 )
 
 // NewVagrantPlugin creates an instance plugin for vagrant.

pkg/example/instance/vagrant/main.go

@@ -2,11 +2,14 @@ package main
 
 import (
 	"os"
-	"text/template"
+	"path/filepath"
+	"strings"
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/infrakit/pkg/cli"
+	"github.com/docker/infrakit/pkg/discovery"
 	instance_plugin "github.com/docker/infrakit/pkg/rpc/instance"
+	"github.com/docker/infrakit/pkg/template"
 	"github.com/spf13/cobra"
 )
 
@@ -24,18 +27,38 @@ func main() {
 		os.Exit(1)
 	}
 	dir := cmd.Flags().String("dir", defaultDir, "Vagrant directory")
-	templFile := cmd.Flags().String("template", "", "Vagrant Template file")
+	templFile := cmd.Flags().String("template", "", "Vagrant Template file, in URL form")
 	cmd.RunE = func(c *cobra.Command, args []string) error {
 
+		opts := template.Options{
+			SocketDir: discovery.Dir(),
+		}
+
 		var templ *template.Template
 		if *templFile == "" {
-			templ = template.Must(template.New("").Parse(VagrantFile))
+			t, err := template.NewTemplate("str://"+VagrantFile, opts)
+			if err != nil {
+				return err
+			}
+			templ = t
 		} else {
-			var err error
-			templ, err = template.ParseFiles()
+
+			// For compatiblity with old code, append a file:// if the
+			// value is just a path
+			if strings.Index(*templFile, "://") == -1 {
+
+				p, err := filepath.Abs(*templFile)
+				if err != nil {
+					return err
+				}
+				*templFile = "file://localhost" + p
+			}
+
+			t, err := template.NewTemplate(*templFile, opts)
 			if err != nil {
 				return err
 			}
+			templ = t
 		}
 
 		cli.SetLogLevel(*logLevel)