fix(docker.bzl): avoid duplicate tags

README.md

@@ -19,20 +19,21 @@ Provides:
 See [releases] page for an `http_archive` of the latest `@pycross_image`.
 
 Examples:
-- [@rules_oci example](example/oci/WORKSPACE.in).
-- [@rules_docker example](example/docker/WORKSPACE.in).
+
+- [@rules_oci example](example/oci/WORKSPACE.in)
+- [@rules_docker example](example/docker/WORKSPACE.in)
 
 A few notes about the workspace setup:
 
 - It's divided into "steps" based on load statement dependencies.  `step1.bzl`
   only depends on things declared in `repositories.bzl`, `step2.bzl` depends on
-  things declared in `step3.bzl`, etc (this pattern is from
+  things declared in `step1.bzl`, etc (this pattern is from
   [tensorflow](https://github.com/tensorflow/tensorflow/tree/master/tensorflow)).
-- Your workspace may already have many of the dependencies.  Some of the
+- Your workspace may already contain some of these dependencies.  Also, selected
   external workspace names may be differ from yours. Use the example as a study
   guide rather than canonical reference.
 - The examples are only tested with the older `WORKSPACE`.  The rules may not be
-  compatible with bzlmod yet.
+  compatible with `bzlmod` yet.
 
 ## How it Works
 
@@ -43,7 +44,7 @@ graph TD;
     numpy{{numpy}}
     grpclib{{grpclib}}
 
-    subgraph linux_x86_64["linuxx86_64\n"]
+    subgraph linux_x86_64
         image.tar-->image;
         image-->app_layer;
         image-->site_packages_layer;

bazel/rules/docker.bzl

@@ -6,6 +6,7 @@ def py_image(
         binary,
         base = "@pycross_image_base_container//image",
         layers = [],
+        tags = [],
         **kwargs):
     """
     py_image is a macro that instantiates an container_image from a py_binary rule
@@ -15,6 +16,7 @@ def py_image(
         binary: target label of the py_binary rule
         base: target label of the base image
         layers: additional container_layer targets
+        tags: additional bazel tags for the container_image
         **kwargs: additional arguments for the pycross_binary and container_image rules
     """
 
@@ -42,6 +44,6 @@ def py_image(
         entrypoint = metadata.entrypoint,
         cmd = metadata.cmd,
         workdir = metadata.workdir,
-        tags = [metadata.repo_tag],
+        tags = [metadata.repo_tag] + tags,
         **kwargs
     )

example/BUILD.bazel

@@ -19,7 +19,6 @@ example_test(
 example_test(
     name = "docker",
     srcs = [
-        "docker/.bazelrc",
         "docker/.bazelversion",
         "docker/.docker/config.json",
         "docker/.dockerconfig.json",

example/local.WORKSPACE

@@ -2,5 +2,3 @@ local_repository(
     name = "pycross_image",
     path = "../pycross_image",
 )
-
-# -----------------------------------------