add support for multiple requirement input files

Revise dependency_resolver.py to use `click`
Avoid mutating `sys.argv`

Co-authored-by: Logan Pulley <lpulley@ocient.com>

Author: cj81499

docs/pip.md

@@ -48,7 +48,7 @@ def compile_pip_requirements(
         extra_deps: extra dependencies passed to pip-compile.
         py_binary: the py_binary rule to be used.
         py_test: the py_test rule to be used.
-        requirements_in: file expressing desired dependencies.
+        requirements_in: file(s) expressing desired dependencies.
         requirements_txt: result of "compiling" the requirements.in file.
         requirements_linux: File of linux specific resolve output to check validate if requirement.in has changes.
         requirements_darwin: File of darwin specific resolve output to check validate if requirement.in has changes.
@@ -69,16 +69,17 @@ def compile_pip_requirements(
         visibility = visibility,
     )
 
-    data = [name, requirements_in, requirements_txt] + [f for f in (requirements_linux, requirements_darwin, requirements_windows) if f != None]
+    if type(requirements_in) == "string":
+        requirements_in = [requirements_in]
+    data = [name] + requirements_in + [requirements_txt] + [f for f in (requirements_linux, requirements_darwin, requirements_windows) if f != None]
 
     # Use the Label constructor so this is expanded in the context of the file
     # where it appears, which is to say, in @rules_python
     pip_compile = Label("//python/pip_install/tools/dependency_resolver:dependency_resolver.py")
 
     loc = "$(rootpath {})"
 
-    args = [
-        loc.format(requirements_in),
+    args = ["--in={}".format(loc.format(f)) for f in requirements_in] + [
         loc.format(requirements_txt),
         "//%s:%s.update" % (native.package_name(), name),
     ]

python/pip_install/requirements.bzl

@@ -69,15 +69,15 @@ def _select_golden_requirements_file(
 
 
 @click.command(context_settings={"ignore_unknown_options": True})
-@click.argument("requirements_in")
+@click.option("--in", "requirements_ins", multiple=True, required=True)
 @click.argument("requirements_txt")
 @click.argument("update_target_label")
 @click.option("--requirements-linux")
 @click.option("--requirements-darwin")
 @click.option("--requirements-windows")
 @click.argument("extra_args", nargs=-1, type=click.UNPROCESSED)
 def main(
-    requirements_in: str,
+    requirements_ins: Tuple[str, ...],
     requirements_txt: str,
     update_target_label: str,
     requirements_linux: Optional[str],
@@ -87,8 +87,8 @@ def main(
 ) -> None:
     # The requirements_in file could be generated, so we will need to remove the
     # absolute prefixes in the locked requirements output file.
-    requirements_in_path = Path(requirements_in)
-    resolved_requirements_in = str(requirements_in_path.resolve())
+    requirements_in_paths = [Path(f) for f in requirements_ins]
+    resolved_requirements_ins = [str(p.resolve()) for p in requirements_in_paths]
 
     # Before loading click, set the locale for its parser.
     # If it leaks through to the system setting, it may fail:
@@ -126,11 +126,16 @@ def main(
 
     argv.append("--generate-hashes")
     argv.append(f"--output-file={requirements_txt if UPDATE else requirements_out}")
-    argv.append(
-        requirements_in if requirements_in_path.exists() else resolved_requirements_in
+    argv.extend(
+        (req_in if req_in_path.exists() else resolved_req_in)
+        for req_in, req_in_path, resolved_req_in in zip(
+            requirements_ins, requirements_in_paths, resolved_requirements_ins
+        )
     )
     argv.extend(extra_args)
 
+    argv.extend(extra_args)
+
     if UPDATE:
         print("Updating " + requirements_txt)
         if "BUILD_WORKSPACE_DIRECTORY" in os.environ:
@@ -156,7 +161,7 @@ def main(
                 print(
                     "pip-compile exited with code 2. This means that pip-compile found "
                     "incompatible requirements or could not find a version that matches "
-                    f"the install requirement in {requirements_in}.",
+                    f"the install requirement in one of {requirements_ins}.",
                     file=sys.stderr,
                 )
                 sys.exit(1)