Set parameters for running flow instead of any imported (Netflix#1691)

* Set parameters for running flow instead of any imported

This fixes the issue where parameters for multiple imported flows
are displayed instead of the running one when multple flows are
in the same file with parameters.

Also:
1. Change to use Exception as bare except is bad practice / fails
flake8.
2. Switch to editable/develop install so any code changes would be
   effective without reinstalling. Much faster to iterate changes.

* suggested changes

* restore except blocks

---------

Co-authored-by: Max Zheng <[email protected]>

metaflow/flowspec.py

@@ -7,7 +7,7 @@
 from types import FunctionType, MethodType
 from typing import Any, Callable, List, Optional, Tuple
 
-from . import cmd_with_io
+from . import cmd_with_io, parameters
 from .parameters import DelayedEvaluationParameter, Parameter
 from .exception import (
     MetaflowException,
@@ -100,6 +100,9 @@ def __init__(self, use_cli=True):
         self._graph = FlowGraph(self.__class__)
         self._steps = [getattr(self, node.name) for node in self._graph]
 
+        # This must be set before calling cli.main() below (or specifically, add_custom_parameters)
+        parameters.parameters = [p for _, p in self._get_parameters()]
+
         if use_cli:
             # we import cli here to make sure custom parameters in
             # args.py get fully evaluated before cli.py is imported.

metaflow/parameters.py

@@ -31,11 +31,7 @@
     ],
 )
 
-# currently we execute only one flow per process, so we can treat
-# Parameters globally. If this was to change, it should/might be
-# possible to move these globals in a FlowSpec (instance) specific
-# closure.
-parameters = []
+parameters = []  # Set by FlowSpec.__init__()
 context_proto = None
 
 
@@ -335,7 +331,6 @@ def __init__(
                 "Parameter *%s*: Separator is only allowed "
                 "for string parameters." % name
             )
-        parameters.append(self)
 
     def option_kwargs(self, deploy_mode):
         kwargs = self.kwargs

test_runner

@@ -5,7 +5,7 @@ set -o errexit -o nounset -o pipefail
 install_deps() {
   for version in 2 3;
   do
-    python$version -m pip install . 
+    python$version -m pip install .
   done
 }
 

tox.ini

@@ -3,4 +3,3 @@
 [testenv]
 allowlist_externals = ./test_runner
 commands = ./test_runner
-