[Feature] Add rez-pip extra args passthrough

src/rez/cli/pip.py

@@ -2,6 +2,7 @@
 Install a pip-compatible python package, and its dependencies, as rez packages.
 """
 from __future__ import print_function
+from argparse import REMAINDER
 
 
 def setup_parser(parser, completions=False):
@@ -30,7 +31,10 @@ def setup_parser(parser, completions=False):
     parser.add_argument(
         "PACKAGE",
         help="package to install or archive/url to install from")
-
+    parser.add_argument(
+        "-e", "--extra", nargs=REMAINDER,
+        help="extra args passthrough to pip install (overrides pre-configured args if specified)"
+    )
 
 def command(opts, parser, extra_arg_groups=None):
     from rez.pip import pip_install_package, run_pip_command
@@ -59,7 +63,8 @@ def command(opts, parser, extra_arg_groups=None):
         pip_version=opts.pip_ver,
         python_version=opts.py_ver,
         release=opts.release,
-        prefix=opts.prefix)
+        prefix=opts.prefix,
+        extra_args=opts.extra)
 
     # print summary
     #

src/rez/config.py

@@ -308,6 +308,7 @@ def _parse_env_var(self, value):
     "implicit_styles":                              OptionalStrList,
     "alias_styles":                                 OptionalStrList,
     "memcached_uri":                                OptionalStrList,
+    "pip_extra_args":                               OptionalStrList,
     "local_packages_path":                          Str,
     "release_packages_path":                        Str,
     "dot_image_format":                             Str,

src/rez/pip.py

@@ -198,7 +198,8 @@ def find_pip_from_context(python_version, pip_version=None):
 
 
 def pip_install_package(source_name, pip_version=None, python_version=None,
-                        mode=InstallMode.min_deps, release=False, prefix=None):
+                        mode=InstallMode.min_deps, release=False, prefix=None,
+                        extra_args=None):
     """Install a pip-compatible python package as a rez package.
     Args:
         source_name (str): Name of package or archive/url containing the pip
@@ -212,6 +213,7 @@ def pip_install_package(source_name, pip_version=None, python_version=None,
             managed.
         release (bool): If True, install as a released package; otherwise, it
             will be installed as a local package.
+        extra_args (List[str]): Additional options to the pip install command.
 
     Returns:
         2-tuple:
@@ -249,13 +251,30 @@ def pip_install_package(source_name, pip_version=None, python_version=None,
         context.print_info(buf)
         _log(buf.getvalue())
 
+    # preconfigured options
+    pre_configured = ["--use-pep517", "--target=%s" % destpath]
+
+    # gather additional pip install options
+    pip_extra_opts = extra_args if extra_args else config.pip_extra_args
+
+    # make sure that the target option is overridden if supplied
+    if any("--target=" in opt for opt in pip_extra_opts):
+        # extra args redefines the target option so ignore pre-configured one
+        pre_configured = pre_configured[0:1]
+    # disable pep517 if forced
+    if "--no-use-pep517" in pip_extra_opts:
+        pre_configured = []
+
+    # keep unique opts
+    opts = list(set(pre_configured + pip_extra_opts))
+
     # Build pip commandline
     cmd = [
-        py_exe, "-m", "pip", "install",
-        "--use-pep517",
-        "--target=%s" % destpath
+        py_exe, "-m", "pip", "install"
     ]
 
+    cmd.extend(opts)
+
     if mode == InstallMode.no_deps:
         cmd.append("--no-deps")
     cmd.append(source_name)

src/rez/rezconfig.py

@@ -694,6 +694,15 @@
 #       launched without extension from windows and other systems.
 create_executable_script_mode = "single"
 
+# Configurable pip extra arguments passed to the rez-pip install command.
+# Since the rez-pip install command already includes some pre-configured
+# arguments (target, use-pep517) this setting can potentially override the
+# default configuration in a way which can cause package installation issues.
+# It is recommended to refrain from overriding the default arguments and only
+# use this setting for additional arguments that might be needed.
+# https://pip.pypa.io/en/stable/reference/pip_install/#options
+pip_extra_args = []
+
 
 ###############################################################################
 # Rez-1 Compatibility