Improve ros_launch support for launch files

Author: julianadrianheine

bazel_ros2_rules/lib/ament_index.bzl

@@ -46,100 +46,140 @@ ament_index_prefixes = aspect(
 Recursively aggregates AmentIndex prefixes from dependencies into one provider.
 """
 
-def _ament_index_share_files_impl(ctx):
-    # declare that a "package" with the given name exists
+def _ament_index_files_impl(ctx):
     package_marker_path = paths.join(
         ctx.attr.prefix,
         "share/ament_index/resource_index/packages/",
         ctx.attr.package_name,
     )
     package_marker_out = ctx.actions.declare_file(package_marker_path)
-    ctx.actions.write(
-        output = package_marker_out,
-        content = "",
-    )
+    ctx.actions.write(output = package_marker_out, content = "")
 
-    # Symlink sources into the share directory
-    runfiles_symlinks = {
-        package_marker_path: package_marker_out,
-    }
+    root_symlinks = {package_marker_path: package_marker_out}
 
     for src in ctx.attr.srcs:
-        # src is a target that could have multiple files
-        for file in src.files.to_list():
-            sp = file.short_path
-            if sp.startswith(ctx.attr.strip_prefix):
-                sp = sp[len(ctx.attr.strip_prefix):]
+        if ctx.attr.subdirectory == "lib":
+            exe_file = src.files_to_run.executable
             symlink_path = paths.join(
                 ctx.attr.prefix,
-                "share",
+                "lib",
                 ctx.attr.package_name,
-                sp,
+                exe_file.basename,
             )
-            runfiles_symlinks[symlink_path] = file
+            root_symlinks[symlink_path] = exe_file
+        else:
+            for file in src.files.to_list():
+                sp = file.short_path
+                if sp.startswith(ctx.attr.strip_prefix):
+                    sp = sp[len(ctx.attr.strip_prefix):]
+                symlink_path = paths.join(
+                    ctx.attr.prefix,
+                    ctx.attr.subdirectory,
+                    ctx.attr.package_name,
+                    sp,
+                )
+                root_symlinks[symlink_path] = file
 
     return [
         AmentIndex(prefix = ctx.attr.prefix),
         DefaultInfo(
-            runfiles = ctx.runfiles(root_symlinks = runfiles_symlinks),
+            runfiles = ctx.runfiles(root_symlinks = root_symlinks),
         ),
     ]
 
-ament_index_share_files = rule(
+_ament_index_files = rule(
     attrs = dict(
         package_name = attr.string(mandatory = True),
         srcs = attr.label_list(
             mandatory = True,
             allow_empty = False,
             allow_files = True,
         ),
+        subdirectory = attr.string(default = "share"),
         # A prefix is required because the shim can't prepend the runfiles
         # root to AMENT_PREFIX_PATH
         prefix = attr.string(default = "ament_index_share_files"),
         strip_prefix = attr.string(default = ""),
     ),
-    implementation = _ament_index_share_files_impl,
+    implementation = _ament_index_files_impl,
     output_to_genfiles = True,
     provides = [AmentIndex],
 )
-"""
-Creates an ament resource index and share/ directory for a single package.
-
-This creates both a package marker for a package, and a share directory
-for that package.
-Files in `srcs` will be added to `share/package_name`.
-A target depending on this one will be able to access the files in the
-share directory using the package's share directory joined with the
-files they expect.
-
-    d = ament_index_cpp::get_package_share_directory("package_name")
-    file = join(d, "short_path of file")
-
-Note that this works only when bazel creates runfiles links,
-and not just a *.runfiles_manifest (which it might do on an unsupported
-platform like Windows, or with `--nobuild_runfile_links`).
-
-Note that the same `package_name` for ROS 2 packages should not be used
-in multiple different rules spread across multiple Bazel packages.
-This is called "overriding", and it's not currently supported.
-Currently if the two calls to `ament_index_share_files` also have
-the same value for "prefix", then a target depending on both may
-be able to find resources from both rules, but that behavior is not
-guaranteed.
-TODO(sloretz) detect and error when a target is given two ament indexes
-with the same package.
-
-Args:
-    package_name: name of a ROS 2 package to which these share files belong
-    srcs: files to put into the share directory
-    prefix: optional prefix to give to the generated runfiles.
-    strip_prefix: optional prefix to strip from the short_path of the files
-
-Provides:
-    AmentIndex: a prefix path where the ament resource index was generated.
-    DefaultInfo: folders and symlinked files to add to the runfiles of a
-      dependent target.
-
-See https://github.com/ament/ament_cmake/blob/master/ament_cmake_core/doc/resource_index.md
-for further reference.
-"""  # noqa
+
+def ament_index_share_files(name, package_name, srcs, prefix = "ament_index_share_files", strip_prefix = "", **kwargs):
+    """Creates an ament resource index and share/ directory for a single package.
+
+    Files in `srcs` will be added to `<prefix>/share/<package_name>/`.
+    A target depending on this one will be able to access the files in the
+    share directory using the package's share directory joined with the
+    files they expect.
+
+        d = ament_index_cpp::get_package_share_directory("package_name")
+        file = join(d, "short_path of file")
+
+    Note that this works only when bazel creates runfiles links,
+    and not just a *.runfiles_manifest (which it might do on an unsupported
+    platform like Windows, or with `--nobuild_runfile_links`).
+
+    Note that the same `package_name` for ROS 2 packages should not be used
+    in multiple different rules spread across multiple Bazel packages.
+    This is called "overriding", and it's not currently supported.
+    Currently if the two calls to `ament_index_share_files` also have
+    the same value for "prefix", then a target depending on both may
+    be able to find resources from both rules, but that behavior is not
+    guaranteed.
+    TODO(sloretz) detect and error when a target is given two ament indexes
+    with the same package.
+
+    Args:
+        package_name: name of a ROS 2 package to which these share files belong
+        srcs: files to put into the share directory
+        prefix: optional prefix to give to the generated runfiles.
+        strip_prefix: optional prefix to strip from the short_path of the files
+
+    Provides:
+        AmentIndex: a prefix path where the ament resource index was generated.
+        DefaultInfo: folders and symlinked files to add to the runfiles of a
+          dependent target.
+
+    See https://github.com/ament/ament_cmake/blob/master/ament_cmake_core/doc/resource_index.md
+    for further reference.
+    """  # noqa
+    _ament_index_files(
+        name = name,
+        package_name = package_name,
+        srcs = srcs,
+        subdirectory = "share",
+        prefix = prefix,
+        strip_prefix = strip_prefix,
+        **kwargs
+    )
+
+def ament_index_executables(name, package_name, srcs, prefix = "ament_index_share_files", **kwargs):
+    """Creates an ament resource index that exposes Bazel-built executables under
+    `<prefix>/lib/<package_name>/`, enabling launch_ros.actions.Node(package=...,
+    executable=...) to find them without a colcon install space.
+
+    When added to the `data=` of a ros_launch() target, the shim injects
+    `<prefix>` into AMENT_PREFIX_PATH so ROS 2 libexec lookup succeeds:
+
+        launch_ros.actions.Node(package="my_pkg", executable="my_node")
+        # resolves to: <prefix>/lib/my_pkg/my_node  ✓
+
+    Args:
+        package_name: the ROS 2 package name (must match Node(package=...))
+        srcs: Bazel labels of the executable targets to expose
+        prefix: optional directory prefix for the generated runfiles tree
+
+    Provides:
+        AmentIndex: a prefix path where the ament resource index was generated.
+        DefaultInfo: symlinks and marker files for all executables.
+    """  # noqa
+    _ament_index_files(
+        name = name,
+        package_name = package_name,
+        srcs = srcs,
+        subdirectory = "lib",
+        prefix = prefix,
+        **kwargs
+    )

bazel_ros2_rules/lib/private/ros_py.bzl

@@ -1,5 +1,9 @@
 # -*- python -*-
 
+load(
+    "@bazel_ros2_rules//lib:ament_index.bzl",
+    "ament_index_executables",
+)
 load(
     "@bazel_ros2_rules//lib:kwargs.bzl",
     "filter_to_only_common_kwargs",
@@ -198,6 +202,11 @@ def ros_launch(
         # runfiles.py to use "this repository" in a way that doesn't require
         # bespoke information.
         workspace_name = None,
+        # Optional ROS 2 package name. When set, an ament_index_executables
+        # target is created from the data= labels, enabling
+        # launch_ros.actions.Node(package=..., executable=...) to find
+        # Bazel-built binaries without a colcon install space.
+        package_name = None,
         **kwargs):
     main = "{}_roslaunch_main.py".format(name)
     launch_respath = _make_respath(launch_file, workspace_name)
@@ -218,6 +227,17 @@ def ros_launch(
             REPOSITORY_ROOT + ":ros2",
         ],
     )
+
+    if package_name:
+        index_target = "_{}_ament_index".format(name)
+        ament_index_executables(
+            name = index_target,
+            package_name = package_name,
+            srcs = data,
+            visibility = ["//visibility:private"],
+        )
+        data = data + [":" + index_target]
+
     data = data + [launch_file]
 
     if "tags" not in kwargs:

ros2_example_bazel_installed/ros2_example_apps/BUILD.bazel

@@ -233,7 +233,8 @@ ros_cc_binary(
 # See bazel_ros2_rules/ros2/README.md, Launch Files, for notes on
 # features and limitations.
 
-# Uses a python launch file to spawn the talker and listener.
+# Uses a python launch file to spawn the talker and listener using
+# ExecuteProcess to run the node binaries.
 workspace_name = "ros2_example_bazel_installed"
 
 ros_launch(
@@ -242,7 +243,7 @@ ros_launch(
         ":eg_listener",
         ":eg_talker",
     ],
-    launch_file = "eg_launch.py",
+    launch_file = "roslaunch_eg.py",
     workspace_name = workspace_name,
 )
 
@@ -257,6 +258,19 @@ ros_launch(
     workspace_name = workspace_name,
 )
 
+# Uses launch_ros.actions.Node, the natural ROS 2 pattern, by registering
+# the Bazel-built binaries in a fake ament prefix via package_name=.
+ros_launch(
+    name = "eg_launch_with_action_node",
+    package_name = "ros2_example_apps",
+    data = [
+        ":eg_listener",
+        ":eg_talker",
+    ],
+    launch_file = "eg_launch_with_action_node.py",
+    workspace_name = workspace_name,
+)
+
 ros_py_test(
     name = "roslaunch_eg_test",
     srcs = ["test/roslaunch_eg_test.py"],

ros2_example_bazel_installed/ros2_example_apps/eg_launch_with_action_node.py

@@ -0,0 +1,17 @@
+from launch import LaunchDescription
+import launch_ros.actions
+
+
+def generate_launch_description():
+    return LaunchDescription(
+        [
+            launch_ros.actions.Node(
+                package="ros2_example_apps",
+                executable="eg_talker",
+            ),
+            launch_ros.actions.Node(
+                package="ros2_example_apps",
+                executable="eg_listener",
+            ),
+        ]
+    )

…installed/ros2_example_apps/eg_launch.py …talled/ros2_example_apps/roslaunch_eg.pyros2_example_bazel_installed/ros2_example_apps/eg_launch.py renamed to ros2_example_bazel_installed/ros2_example_apps/roslaunch_eg.py ros2_example_bazel_installed/ros2_example_apps/eg_launch.py renamed to ros2_example_bazel_installed/ros2_example_apps/roslaunch_eg.py

@@ -8,8 +8,8 @@ def generate_launch_description():
     # features and limitations.
     r = runfiles.Create()
     prefix = "ros2_example_bazel_installed/ros2_example_apps"
-    talker_bin = r.Rlocation(f"{prefix}/eg_talker")
-    listener_bin = r.Rlocation(f"{prefix}/eg_listener")
+    talker_bin = r.Rlocation(f"{prefix}/eg_talker", source_repo="")
+    listener_bin = r.Rlocation(f"{prefix}/eg_listener", source_repo="")
 
     return LaunchDescription(
         [