feat(user): Allow overriding the default shell

docs/apko_file.md

@@ -63,6 +63,7 @@ accounts:
   users:
     - username: nginx
       uid: 10000
+      shell: /bin/sh
   run-as: nginx
 
 # optional environment configuration
@@ -160,6 +161,7 @@ There are several child elements:
   users:
     - username: nginx
       uid: 10000
+      shell: /bin/sh
 ```
  - `run-as`: name of the user to run the main process under (should match a username or uid specified in
    users)

pkg/build/accounts.go

@@ -41,14 +41,17 @@ func userToUserEntry(user types.User) passwd.UserEntry {
 	if user.GID == 0 {
 		user.GID = user.UID
 	}
+	if user.Shell == "" {
+		user.Shell = "/bin/sh"
+	}
 	return passwd.UserEntry{
 		UserName: user.UserName,
 		UID:      user.UID,
 		GID:      user.GID,
 		HomeDir:  "/home/" + user.UserName,
 		Password: "x",
 		Info:     "Account created by apko",
-		Shell:    "/bin/sh",
+		Shell:    user.Shell,
 	}
 }
 

pkg/build/types/schema.json

@@ -253,6 +253,10 @@
         "gid": {
           "type": "integer",
           "description": "Required: The user's group ID"
+        },
+        "shell": {
+          "type": "string",
+          "description": "Required: The user's shell"
         }
       },
       "additionalProperties": false,

pkg/build/types/types.go

@@ -29,6 +29,8 @@ type User struct {
 	UID uint32 `json:"uid,omitempty"`
 	// Required: The user's group ID
 	GID uint32 `json:"gid,omitempty"`
+	// Required: The user's shell
+	Shell string `json:"shell,omitempty"`
 }
 
 type Group struct {