fix: useradd docker-client gid handling

README.md

@@ -229,7 +229,7 @@ The useradd partial contains a devcontainer bake config file. See [Devcontainer
 | Variable | Required | Default | Effect |
 | --- | --- | --- | --- |
 | `USER` | ✗ | `"root"` | See [useradd Dockerfile](#useradd-dockerfile-usage) |
-| `EXTRA_GID_ARGS` | ✗ | `""` | See [useradd Dockerfile](#useradd-dockerfile-usage) |
+| `EXTRA_GID_ARGS` | ✗ | `""` or `DOCKER_CLIENT_EXTRA_GID_ARGS` if defined | See [useradd Dockerfile](#useradd-dockerfile-usage) |
 | `UID` | ✗ | `0` | Maps to `USER_UID`. See [useradd Dockerfile](#useradd-dockerfile-usage) |
 | `GID` | ✗ | `${UID}` | Maps to `USER_GID`.See [useradd Dockerfile](#useradd-dockerfile-usage) |
 

docker-client/devcontainer-bake.hcl

@@ -1,8 +1,8 @@
 variable "DOCKER_GID" {
   default = "800"
 }
-// Set EXTRA_GID_ARGS to include a Docker group in case the useradd partial will be included
-variable "EXTRA_GID_ARGS" {
+// Define an extra GID arg with the Docker group ID in case the useradd partial will be included
+variable "DOCKER_CLIENT_EXTRA_GID_ARGS" {
   default = "--gid ${DOCKER_GID}"
 }
 

useradd/devcontainer-bake.hcl

@@ -1,5 +1,5 @@
 variable "EXTRA_GID_ARGS" {
-  default = ""
+  default = try(DOCKER_CLIENT_EXTRA_GID_ARGS, "")
 }
 variable "USER" {
   default = "root"