bindings: package ns-3 as a pip wheel

Includes:
- Python examples to test Brite, Click and Openflow
- CI jobs for manylinux packaging of pip wheel
- Support for Linux distributions with lib and lib64 directories
- Configuration of RPATH not to require setting LD_LIBRARY_PATH

Signed-off-by: Gabriel Ferreira <gabrielcarvfer@gmail.com>

build-support/macros-and-definitions.cmake

@@ -36,6 +36,9 @@ option(NS3_ENABLE_SUDO
        "Set executables ownership to root and enable the SUID flag" OFF
 )
 
+# a flag that controls some aspects related to pip packaging
+option(NS3_PIP_PACKAGING "Control aspects related to pip wheel packaging" OFF)
+
 # Replace default CMake messages (logging) with custom colored messages as early
 # as possible
 include(${PROJECT_SOURCE_DIR}/build-support/3rd-party/colored-messages.cmake)
@@ -152,6 +155,25 @@ link_directories(${CMAKE_OUTPUT_DIRECTORY}/lib)
 include(GNUInstallDirs)
 include(build-support/custom-modules/ns3-cmake-package.cmake)
 
+# Set RPATH not too need LD_LIBRARY_PATH after installing
+set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib:$ORIGIN/:$ORIGIN/../lib")
+
+# Add the 64 suffix to the library path when manually requested with the
+# -DNS3_USE_LIB64=ON flag. May be necessary depending on the target platform.
+# This is used to properly build the manylinux pip wheel.
+if(${NS3_USE_LIB64})
+  link_directories(${CMAKE_OUTPUT_DIRECTORY}/lib64)
+  set(CMAKE_INSTALL_RPATH
+      "${CMAKE_INSTALL_RPATH}:${CMAKE_INSTALL_PREFIX}/lib64:$ORIGIN/:$ORIGIN/../lib64"
+  )
+endif()
+
+# cmake-format: off
+# You are a wizard, Harry!
+# source: https://gitlab.kitware.com/cmake/community/-/wikis/doc/cmake/RPATH-handling
+# cmake-format: on
+set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
+
 if(${XCODE})
   # Is that so hard not to break people's CI, AAPL? Why would you output the
   # targets to a Debug/Release subfolder? Why?
@@ -816,7 +838,7 @@ macro(process_options)
       find_package(Python3 COMPONENTS Interpreter Development)
     else()
       # cmake-format: off
-      set(Python_ADDITIONAL_VERSIONS 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9)
+      set(Python_ADDITIONAL_VERSIONS 3.6 3.7 3.8 3.9 3.10 3.11)
       # cmake-format: on
       find_package(PythonInterp)
       find_package(PythonLibs)
@@ -924,6 +946,9 @@ macro(process_options)
           "Set NS3_BINDINGS_INSTALL_DIR=\"${SUGGESTED_BINDINGS_INSTALL_DIR}\" to install it to the default location."
         )
       else()
+        if(${NS3_BINDINGS_INSTALL_DIR} STREQUAL "INSTALL_PREFIX")
+          set(NS3_BINDINGS_INSTALL_DIR ${CMAKE_INSTALL_PREFIX})
+        endif()
         install(FILES bindings/python/ns__init__.py
                 DESTINATION ${NS3_BINDINGS_INSTALL_DIR}/ns RENAME __init__.py
         )

build-support/pip-wheel/auditwheel-exclude-list.py

@@ -0,0 +1,11 @@
+import os
+
+ns3_path = os.path.dirname(os.path.abspath(os.sep.join([__file__, "../../"])))
+
+for variant in ["lib", "lib64"]:
+    lib_dir = os.path.abspath(os.path.join(ns3_path, f"build/{variant}"))
+    if not os.path.exists(lib_dir):
+        continue
+    for lib in os.listdir(lib_dir):
+        if "libns3" in lib:
+            print(f"--exclude {lib}", end=' ')

build-support/pip-wheel/ns/__init__.py

@@ -0,0 +1,10 @@
+# This is a stub module that loads the actual ns-3
+# bindings from nsnam.ns
+import sys
+
+try:
+    import ns3.ns
+    sys.modules['ns'] = ns3.ns
+except ModuleNotFoundError as e:
+    print("Install the ns3 package with pip install ns3.", file=sys.stderr)
+    exit(-1)

build-support/pip-wheel/visualizer/__init__.py

@@ -0,0 +1,11 @@
+# This is a stub module that loads the actual visualizer
+# from nsnam.visualizer
+import sys
+
+try:
+    import ns3.visualizer
+except ModuleNotFoundError as e:
+    print("Install the ns3 package with pip install ns3.", file=sys.stderr)
+    exit(-1)
+
+from ns3.visualizer import start, register_plugin, set_bounds, add_initialization_hook