Docker: Add full_directory interpolation value for repository configuration.

docs/docs/docker/tagging-docker-images.mdx

@@ -131,6 +131,7 @@ docker_image(
 The default placeholders are:
 
 - `{directory}`: The directory the docker_image's BUILD file is in.
+- `{build_file_path}`: The full path to the BUILD file.
 - `{parent_directory}`: The parent directory of `{directory}`.
 - `{name}`: The name of the docker_image target.
 - `{build_args.ARG_NAME}`: Each defined Docker build arg is available for interpolation under the `build_args.` prefix.

src/python/pants/backend/docker/goals/package_image.py

@@ -95,6 +95,7 @@ def format_repository(
         repository_context = InterpolationContext.from_dict(
             {
                 "directory": os.path.basename(self.address.spec_path),
+                "build_file_path": self.address.spec_path,
                 "name": self.address.target_name,
                 "parent_directory": os.path.basename(os.path.dirname(self.address.spec_path)),
                 "default_repository": default_repository,

src/python/pants/backend/docker/goals/package_image_test.py

@@ -272,6 +272,11 @@ def test_build_docker_image(rule_runner: RuleRunner) -> None:
                   name="test5",
                   image_tags=["latest", "alpha-1.0", "alpha-1"],
                 )
+                docker_image(
+                  name="test6",
+                  image_tags=["1.2.3"],
+                  repository="xyz/{build_file_path}/{name}",
+                )
                 docker_image(
                   name="err1",
                   repository="{bad_template}",
@@ -365,11 +370,16 @@ def test_build_docker_image(rule_runner: RuleRunner) -> None:
             )
         ],
     )
+    assert_build(
+        rule_runner,
+        Address("docker/test", target_name="test6"),
+        "Built docker image: xyz/docker/test/test6:1.2.3",
+    )
 
     err1 = (
         r"Invalid value for the `repository` field of the `docker_image` target at "
         r"docker/test:err1: '{bad_template}'\.\n\nThe placeholder 'bad_template' is unknown\. "
-        r"Try with one of: build_args, default_repository, directory, name, pants, "
+        r"Try with one of: build_args, build_file_path, default_repository, directory, name, pants, "
         r"parent_directory, tags, target_repository\."
     )
     with pytest.raises(DockerRepositoryNameError, match=err1):

src/python/pants/backend/docker/subsystems/docker_options.py

@@ -108,13 +108,14 @@ def env_vars(self) -> tuple[str, ...]:
             The value is formatted and may reference these variables (in addition to the normal
             placeholders derived from the Dockerfile and build args etc):
 
-            {bullet_list(["name", "directory", "parent_directory", "target_repository"])}
+            {bullet_list(["name", "directory", "parent_directory", "build_file_path", "target_repository"])}
 
             Example: `--default-repository="{{directory}}/{{name}}"`.
 
             The `name` variable is the `docker_image`'s target name, `directory` and
             `parent_directory` are the name of the directory in which the BUILD file is for the
-            target, and its parent directory respectively.
+            target, and its parent directory respectively; and `build_file_path` is the full repository path
+            to the BUILD file.
 
             Use the `repository` field to set this value directly on a `docker_image` target.