Maint: alpine package interface rework

- return concrete struct type
- split interface is sub-interfaces

internal/alpine/alpine.go

@@ -2,24 +2,25 @@
 package alpine
 
 import (
-	"context"
 	"os/user"
 )
 
-type Configurator interface {
+var _ Alpiner = (*Alpine)(nil)
-	CreateUser(username string, uid int) (createdUsername string, err error)
+
-	Version(ctx context.Context) (version string, err error)
+type Alpiner interface {
+	UserCreater
+	VersionGetter
 }
 
-type configurator struct {
+type Alpine struct {
 	alpineReleasePath string
 	passwdPath        string
 	lookupID          func(uid string) (*user.User, error)
 	lookup            func(username string) (*user.User, error)
 }
 
-func NewConfigurator() Configurator {
+func New() *Alpine {
-	return &configurator{
+	return &Alpine{
 		alpineReleasePath: "/etc/alpine-release",
 		passwdPath:        "/etc/passwd",
 		lookupID:          user.LookupId,

internal/alpine/users.go

@@ -12,10 +12,14 @@ var (
 	ErrUserAlreadyExists = errors.New("user already exists")
 )
 
+type UserCreater interface {
+	CreateUser(username string, uid int) (createdUsername string, err error)
+}
+
 // CreateUser creates a user in Alpine with the given UID.
-func (c *configurator) CreateUser(username string, uid int) (createdUsername string, err error) {
+func (a *Alpine) CreateUser(username string, uid int) (createdUsername string, err error) {
 	UIDStr := strconv.Itoa(uid)
-	u, err := c.lookupID(UIDStr)
+	u, err := a.lookupID(UIDStr)
 	_, unknownUID := err.(user.UnknownUserIdError)
 	if err != nil && !unknownUID {
 		return "", err
@@ -28,7 +32,7 @@ func (c *configurator) CreateUser(username string, uid int) (createdUsername str
 		return u.Username, nil
 	}
 
-	u, err = c.lookup(username)
+	u, err = a.lookup(username)
 	_, unknownUsername := err.(user.UnknownUserError)
 	if err != nil && !unknownUsername {
 		return "", err
@@ -39,7 +43,7 @@ func (c *configurator) CreateUser(username string, uid int) (createdUsername str
 			ErrUserAlreadyExists, username, u.Uid, uid)
 	}
 
-	file, err := os.OpenFile(c.passwdPath, os.O_APPEND|os.O_WRONLY, 0644)
+	file, err := os.OpenFile(a.passwdPath, os.O_APPEND|os.O_WRONLY, 0644)
 	if err != nil {
 		return "", err
 	}

internal/alpine/version.go

@@ -7,8 +7,12 @@ import (
 	"strings"
 )
 
-func (c *configurator) Version(ctx context.Context) (version string, err error) {
+type VersionGetter interface {
-	file, err := os.OpenFile(c.alpineReleasePath, os.O_RDONLY, 0)
+	Version(ctx context.Context) (version string, err error)
+}
+
+func (a *Alpine) Version(ctx context.Context) (version string, err error) {
+	file, err := os.OpenFile(a.alpineReleasePath, os.O_RDONLY, 0)
 	if err != nil {
 		return "", err
 	}