polish code: introduce provisioners package

cmd/commit.go

@@ -17,10 +17,8 @@ package cmd
 
 import (
 	"errors"
-	"fmt"
 	"github.com/mhewedy/vermin/vms"
 	"github.com/spf13/cobra"
-	"os"
 )
 
 // commitCmd represents the commit command
@@ -39,10 +37,7 @@ $ vermin commit vm_01 elk/elastic
 		override, _ := cmd.Flags().GetBool("override")
 
 		err := vms.Commit(vmName, imageName, override)
-		if err != nil {
-			fmt.Println(err)
-			os.Exit(1)
-		}
+		exitOnError(err)
 	},
 	Args: func(cmd *cobra.Command, args []string) error {
 		if len(args) < 1 {

cmd/create.go

@@ -18,15 +18,11 @@ package cmd
 import (
 	"errors"
 	"fmt"
+	"github.com/mhewedy/vermin/provisioners"
 	"github.com/mhewedy/vermin/vms"
 	"github.com/spf13/cobra"
-	"os"
-	"strings"
 )
 
-const paramShell = "shell"
-const paramAnsible = "ansible"
-
 // createCmd represents the create command
 var createCmd = &cobra.Command{
 	Use:   "create",
@@ -48,26 +44,20 @@ $ vermin create <image> </path/to/shell/script.sh>
 		var ps vms.ProvisionScript
 
 		if len(args) > 1 {
-			ps.Script = args[1]
-			checkFilePath(ps.Script)
 
 			t, _ := cmd.Flags().GetString("type")
-			switch t {
-			case paramShell:
-				ps.Func = vms.ProvisionShell
-			case paramAnsible:
-				ps.Func = vms.ProvisionAnsible
-			}
+			pf, err := provisioners.Load(t)
+			exitOnError(err)
 
+			ps.Func = pf
+			ps.Script = args[1]
+			checkFilePath(ps.Script)
 		}
 		cpus, _ := cmd.Flags().GetInt("cpus")
 		mem, _ := cmd.Flags().GetInt("mem")
 
 		vmName, err := vms.Create(imageName, ps, cpus, mem)
-		if err != nil {
-			fmt.Println(err)
-			os.Exit(1)
-		}
+		exitOnError(err)
 
 		fmt.Printf("\nVM is ready, to connect to it use:\n$ vermin ssh %s\n", vmName)
 	},
@@ -76,11 +66,6 @@ $ vermin create <image> </path/to/shell/script.sh>
 			return errors.New("Image required\nUse the command 'vermin images' to list all images available")
 		}
 
-		typeStr, _ := cmd.Flags().GetString("type")
-		if !(strings.EqualFold(typeStr, paramShell) || strings.EqualFold(typeStr, paramAnsible)) {
-			return errors.New("provision script type should be either shell or ansible")
-		}
-
 		return nil
 	},
 	ValidArgsFunction: listImages,

cmd/util.go

@@ -17,3 +17,10 @@ func checkFilePath(path string) {
 func preRun(cmd *cobra.Command, args []string) {
 	config.CheckForUpdates(version)
 }
+
+func exitOnError(err error) {
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}

provisioners/ansible.go

@@ -0,0 +1,22 @@
+package provisioners
+
+import (
+	"github.com/mhewedy/vermin/command"
+	"github.com/mhewedy/vermin/ip"
+)
+
+type Ansible struct{}
+
+func (Ansible) Accept(ptype string) bool {
+	return ptype == "ansible"
+}
+
+func (Ansible) Exec(vmName string, script string) error {
+
+	ipAddr, err := ip.Find(vmName, false)
+	if err != nil {
+		return err
+	}
+
+	return command.AnsiblePlaybook(ipAddr, script).Interact()
+}

provisioners/provisioners.go

@@ -0,0 +1,29 @@
+package provisioners
+
+import "fmt"
+
+type Func func(vmName string, script string) error
+
+type Provisioner interface {
+	Accept(ptype string) bool
+	Exec(vmName string, script string) error
+}
+
+func Load(pType string) (Func, error) {
+
+	// TODO in future if we need to implement plugin arch,
+	//  we might construct this slice dynamically by checking some directory of binaries of some name
+	// e.g. vermin-provisioner-<name>
+	ps := []Provisioner{
+		Shell{},
+		Ansible{},
+	}
+
+	for _, p := range ps {
+		if p.Accept(pType) {
+			return p.Exec, nil
+		}
+	}
+
+	return nil, fmt.Errorf("Cannot load provisioner of type: %s", pType)
+}

vms/provision.go → provisioners/shell.go

@@ -1,14 +1,18 @@
-package vms
+package provisioners
 
 import (
-	"github.com/mhewedy/vermin/command"
 	"github.com/mhewedy/vermin/command/scp"
 	"github.com/mhewedy/vermin/command/ssh"
-	"github.com/mhewedy/vermin/ip"
 	"path/filepath"
 )
 
-func ProvisionShell(vmName string, script string) error {
+type Shell struct{}
+
+func (Shell) Accept(ptype string) bool {
+	return "shell" == ptype
+}
+
+func (Shell) Exec(vmName string, script string) error {
 
 	vmFile := "/tmp/" + filepath.Base(script)
 	if err := scp.CopyToVM(vmName, script, vmFile); err != nil {
@@ -23,13 +27,3 @@ func ProvisionShell(vmName string, script string) error {
 
 	return nil
 }
-
-func ProvisionAnsible(vmName string, script string) error {
-
-	ipAddr, err := ip.Find(vmName, false)
-	if err != nil {
-		return err
-	}
-
-	return command.AnsiblePlaybook(ipAddr, script).Interact()
-}

vms/create.go

@@ -8,6 +8,7 @@ import (
 	"github.com/mhewedy/vermin/db"
 	"github.com/mhewedy/vermin/images"
 	"github.com/mhewedy/vermin/progress"
+	"github.com/mhewedy/vermin/provisioners"
 	"os"
 	"runtime"
 	"sort"
@@ -17,7 +18,7 @@ import (
 
 type ProvisionScript struct {
 	Script string
-	Func   func(vmName string, script string) error
+	Func   provisioners.Func
 }
 
 func Create(imageName string, ps ProvisionScript, cpus int, mem int) (string, error) {