added docker example

Author: JohnRudolfLewis

examples/MODULE.bazel

@@ -4,6 +4,8 @@ bazel_dep(name = "rules_python", version = "0.36.0")
 bazel_dep(name = "boost.any", version = "1.83.0")
 bazel_dep(name = "boost.smart_ptr", version = "1.83.0")
 bazel_dep(name = "boost.thread", version = "1.83.0")
+bazel_dep(name = "rules_oci", version = "2.0.1")
+bazel_dep(name = "rules_pkg", version = "1.0.1")
 
 # This import is relevant for these examples and this (rules_ros) repository.
 bazel_dep(name = "rules_ros")
@@ -44,3 +46,18 @@ use_repo(
     "urdfdom",
     "urdfdom_headers",
 )
+
+# in order to build an oci image with our ros nodes in it, one
+# needs to define the base image to use, and that must be performed
+# at the module level here. 
+# NOTE: Even though the version of python that the nodes run in is contained
+# in the runfiles, a version of python is required at the system level in order
+# to run the roslaunch command.
+oci = use_extension("@rules_oci//oci:extensions.bzl", "oci")
+oci.pull(
+    name = "rules_ros_base_image",
+    image = "python:3.10-bookworm",
+    digest = "sha256:fd0fa50d997eb56ce560c6e5ca6a1f5cf8fdff87572a16ac07fb1f5ca01eb608",
+    platforms = ["linux/amd64"],
+)
+use_repo(oci, "rules_ros_base_image", "rules_ros_base_image_linux_amd64")

examples/chatter/BUILD.bazel

@@ -19,6 +19,12 @@ load("@rules_ros//ros:launch.bzl", "ros_launch")
 load("@rules_ros//ros:test.bzl", "ros_test")
 load("@rules_ros//ros:topic.bzl", "ros_topic")
 load("@rules_ros//third_party:expand_template.bzl", "expand_template")
+load(
+    "@rules_oci//oci:defs.bzl", 
+    "oci_image", 
+    "oci_load"
+)
+load("@rules_pkg//pkg:pkg.bzl", "pkg_tar")
 
 # Handling of ROS messages & services resembles to some extent Bazel's rules for
 # handling protobuf messages (e.g. proto_library and cc_proto_library).
@@ -127,3 +133,37 @@ ros_topic(
     name = "rostopic",
     deps = [":chatter"],
 )
+
+
+# packages up the nodes, launch file, and all the other required runfiles.
+# Note the symlink is required in order to place the files where ros_launch is
+# expecting them to be.
+pkg_tar(
+    name = "chatter_tar",
+    srcs = [
+        ":chatter",
+    ],
+    include_runfiles = True,
+    package_dir = "chatter",
+    symlinks = {
+        "/chatter/chatter.runfiles/_main/external": "/chatter/chatter.runfiles",
+    }
+)
+
+# builds the oci image on top of the @rules_ros_base_image defined at the MODULE level. 
+oci_image(
+    name = "chatter_oci_image",
+    base = "@rules_ros_base_image",
+    tars = [":chatter_tar"],
+    workdir = "/chatter/chatter.runfiles/_main",
+    entrypoint = ["/chatter/chatter"],
+)
+
+# loads the oci image into the docker daemon.
+# Example usage: `bazel run //chatter:chatter_oci_load`
+# Then to run the container: `docker run -it --rm chatter:latest`
+oci_load(
+    name = "chatter_oci_load",
+    image = ":chatter_oci_image",
+    repo_tags = ["chatter:latest"],
+)