From cf00cb2a6b633b565affbd52b865c20a7557c69c Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Sat, 9 Sep 2023 03:57:10 +0200
Subject: [PATCH 01/10] track component initializations

---
 src/batou/component.py   |  9 +++++++++
 src/batou/environment.py | 12 +++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/batou/component.py b/src/batou/component.py
index 2bda8af6..226c4d48 100644
--- a/src/batou/component.py
+++ b/src/batou/component.py
@@ -7,6 +7,7 @@
 import sys
 import types
 import weakref
+from typing import List
 
 import batou
 import batou.c
@@ -146,6 +147,13 @@ class Component(object):
     #: working directory to this.
     workdir: str = None
 
+    #: A list of all component instances that have been created. When
+    #: a component is created (__init__) it is added to this list.
+    #: After the configuration phase, this list is checked for
+    #: components that have component._prepared == False and
+    #: warns about them.
+    instances: List["Component"] = []
+
     @property
     def defdir(self):
         """(*readonly*) The definition directory
@@ -188,6 +196,7 @@ def root(self):
     _prepared = False
 
     def __init__(self, namevar=None, **kw):
+        Component.instances.append(self)
         self.timer = batou.utils.Timer(self.__class__.__name__)
         # Are any keyword arguments undefined attributes?
         # This is a somewhat rough implementation as it allows overriding
diff --git a/src/batou/environment.py b/src/batou/environment.py
index b52a373b..c2ae2037 100644
--- a/src/batou/environment.py
+++ b/src/batou/environment.py
@@ -31,7 +31,7 @@
     UnusedResources,
 )
 from batou._output import output
-from batou.component import ComponentDefinition, RootComponent
+from batou.component import Component, ComponentDefinition, RootComponent
 from batou.provision import Provisioner
 from batou.repository import Repository
 from batou.utils import CycleError, cmd
@@ -566,6 +566,16 @@ def configure(self):
                 UnusedResources.from_context(self.resources.unused)
             )
 
+        # if any of Component.instances has ._prepared == False, then
+        # warn via output.annotate
+        for component in Component.instances:
+            if not component._prepared:
+                output.annotate(
+                    "Component {} was not prepared.".format(
+                        component.__class__.__name__
+                    ),
+                )
+
         for root in order:
             root.log_finish_configure()
 

From c672bc2a467e85bb5d44e0c08476e37ca602a6b3 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Tue, 19 Dec 2023 01:50:47 +0100
Subject: [PATCH 02/10] Add warning for unprepared (not configured) components

---
 src/batou/environment.py | 15 ++++++++-------
 src/batou/remote_core.py |  6 ++++++
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/batou/environment.py b/src/batou/environment.py
index c2ae2037..592fb281 100644
--- a/src/batou/environment.py
+++ b/src/batou/environment.py
@@ -568,13 +568,14 @@ def configure(self):
 
         # if any of Component.instances has ._prepared == False, then
         # warn via output.annotate
-        for component in Component.instances:
-            if not component._prepared:
-                output.annotate(
-                    "Component {} was not prepared.".format(
-                        component.__class__.__name__
-                    ),
-                )
+        if not exceptions:
+            for component in Component.instances:
+                if not component._prepared:
+                    output.warn(
+                        "A Component '{}' was initialized but was not prepared (configured).\nThis may not be what you want".format(
+                            component.__class__.__name__
+                        ),
+                    )
 
         for root in order:
             root.log_finish_configure()
diff --git a/src/batou/remote_core.py b/src/batou/remote_core.py
index b9b1cd85..9cc2b2d5 100644
--- a/src/batou/remote_core.py
+++ b/src/batou/remote_core.py
@@ -107,6 +107,12 @@ def error(self, message, exc_info=None, debug=False):
             out = "      " + out.replace("\n", "\n      ") + "\n"
             self.backend.write(out, red=True)
 
+    def warn(self, message, debug=False):
+        if debug and not self.enable_debug:
+            return
+        self.flush_buffer()
+        self.step("WARN", message, yellow=True)
+
 
 class ChannelBackend(object):
     def __init__(self, channel):

From 92bee65269d4cce6159e07f1eeb9562672c06062 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Tue, 19 Dec 2023 02:38:52 +0100
Subject: [PATCH 03/10] reset application state in test_environment.py test

---
 src/batou/tests/test_environment.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/batou/tests/test_environment.py b/src/batou/tests/test_environment.py
index f72d5060..a40fdc29 100644
--- a/src/batou/tests/test_environment.py
+++ b/src/batou/tests/test_environment.py
@@ -4,6 +4,7 @@
 
 import batou
 import batou.utils
+from batou.component import Component
 from batou.environment import Config, Environment
 from batou.host import Host
 
@@ -286,6 +287,10 @@ def _get_components(hostname):
 
 @mock.patch("batou.remote_core.Output.line")
 def test_log_in_component_configure_is_put_out(output, sample_service):
+    # we are deploying in this test
+    # so we will reset some application state
+    Component.instances = []
+    # this is for tracking which components are used and not
     e = Environment("test-with-provide-require")
     e.load()
     e.configure()

From 22e61ee5b9eed9fa3d73c9a40adea484078190f3 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Wed, 20 Dec 2023 15:12:37 +0100
Subject: [PATCH 04/10] Report root node for unused components, test

---
 src/batou/__init__.py                         | 21 +++++++++++++
 src/batou/environment.py                      | 30 ++++++++++---------
 .../components/hello/component.py             |  9 ++++++
 .../environments/test-unused/environment.cfg  |  5 ++++
 src/batou/tests/test_environment.py           | 10 ++++++-
 5 files changed, 60 insertions(+), 15 deletions(-)
 create mode 100644 src/batou/tests/fixture/sample_service/environments/test-unused/environment.cfg

diff --git a/src/batou/__init__.py b/src/batou/__init__.py
index 454f25a1..3b8222fc 100644
--- a/src/batou/__init__.py
+++ b/src/batou/__init__.py
@@ -473,6 +473,27 @@ def report(self):
             )
 
 
+class UnusedComponentsInitialized(ConfigurationError):
+    """Some components were initialized but never used."""
+
+    sort_key = (5, "unused")
+
+    @classmethod
+    def from_context(cls, components, root):
+        self = cls()
+        self.unused_components = []
+        for component in components:
+            self.unused_components.append(repr(component.__class__.__name__))
+        self.root_name = root.name
+        return self
+
+    def __str__(self):
+        return f"Unused components: {', '.join(self.unused_components)}"
+
+    def report(self):
+        output.error(f"Unused components: {', '.join(self.unused_components)}")
+
+
 class UnsatisfiedResources(ConfigurationError):
     """Some required resources were never provided."""
 
diff --git a/src/batou/environment.py b/src/batou/environment.py
index 592fb281..1be15b8d 100644
--- a/src/batou/environment.py
+++ b/src/batou/environment.py
@@ -28,6 +28,7 @@
     SuperfluousSection,
     UnknownComponentConfigurationError,
     UnsatisfiedResources,
+    UnusedComponentsInitialized,
     UnusedResources,
 )
 from batou._output import output
@@ -497,6 +498,7 @@ def configure(self):
 
             for root in working_set:
                 try:
+                    Component.instances.clear()
                     self.resources.reset_component_resources(root)
                     root.overrides = self.overrides.get(root.name, {})
                     root.prepare()
@@ -516,9 +518,20 @@ def configure(self):
                         )
                     )
                 else:
-                    # configured this component successfully
-                    # we won't have to retry it later
-                    continue
+                    unprepared_components = []
+                    for component in Component.instances:
+                        if not component._prepared:
+                            unprepared_components.append(component)
+                    if unprepared_components:
+                        exceptions.append(
+                            UnusedComponentsInitialized.from_context(
+                                unprepared_components, root
+                            )
+                        )
+                    if not exceptions:
+                        # configured this component successfully
+                        # we won't have to retry it later
+                        continue
                 retry.add(root)
 
             retry.update(self.resources.dirty_dependencies)
@@ -566,17 +579,6 @@ def configure(self):
                 UnusedResources.from_context(self.resources.unused)
             )
 
-        # if any of Component.instances has ._prepared == False, then
-        # warn via output.annotate
-        if not exceptions:
-            for component in Component.instances:
-                if not component._prepared:
-                    output.warn(
-                        "A Component '{}' was initialized but was not prepared (configured).\nThis may not be what you want".format(
-                            component.__class__.__name__
-                        ),
-                    )
-
         for root in order:
             root.log_finish_configure()
 
diff --git a/src/batou/tests/fixture/sample_service/components/hello/component.py b/src/batou/tests/fixture/sample_service/components/hello/component.py
index c829c267..844ac859 100644
--- a/src/batou/tests/fixture/sample_service/components/hello/component.py
+++ b/src/batou/tests/fixture/sample_service/components/hello/component.py
@@ -62,3 +62,12 @@ def configure(self):
 class Sub(Component):
     def configure(self):
         self.log("Sub!")
+
+
+class Unused(Component):
+    pass
+
+
+class BadUnused(Component):
+    def configure(self):
+        Unused()
diff --git a/src/batou/tests/fixture/sample_service/environments/test-unused/environment.cfg b/src/batou/tests/fixture/sample_service/environments/test-unused/environment.cfg
new file mode 100644
index 00000000..c67a1166
--- /dev/null
+++ b/src/batou/tests/fixture/sample_service/environments/test-unused/environment.cfg
@@ -0,0 +1,5 @@
+[environment]
+connect_method = local
+
+[hosts]
+localhost = badunused
diff --git a/src/batou/tests/test_environment.py b/src/batou/tests/test_environment.py
index a40fdc29..b9557bba 100644
--- a/src/batou/tests/test_environment.py
+++ b/src/batou/tests/test_environment.py
@@ -4,7 +4,7 @@
 
 import batou
 import batou.utils
-from batou.component import Component
+from batou.component import Component, RootComponent
 from batou.environment import Config, Environment
 from batou.host import Host
 
@@ -336,3 +336,11 @@ def test_resolver_overrides_invalid_address(sample_service):
     errors = e.configure()
     assert len(errors) == 1
     assert "thisisinvalid" == errors[0].address
+
+
+def test_unused_components_get_reported(sample_service):
+    e = Environment("test-unused")
+    e.load()
+    errors = e.configure()
+
+    assert any(isinstance(e, batou.UnusedComponentsInitialized) for e in errors)

From 939cdeb6b3f0391cf2998d7120bd423aa433f637 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Wed, 20 Dec 2023 15:21:39 +0100
Subject: [PATCH 05/10] Remove unnecessary code in test_environment.py

---
 src/batou/tests/test_environment.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/src/batou/tests/test_environment.py b/src/batou/tests/test_environment.py
index b9557bba..bd96c983 100644
--- a/src/batou/tests/test_environment.py
+++ b/src/batou/tests/test_environment.py
@@ -287,10 +287,6 @@ def _get_components(hostname):
 
 @mock.patch("batou.remote_core.Output.line")
 def test_log_in_component_configure_is_put_out(output, sample_service):
-    # we are deploying in this test
-    # so we will reset some application state
-    Component.instances = []
-    # this is for tracking which components are used and not
     e = Environment("test-with-provide-require")
     e.load()
     e.configure()

From 5380434ffc083b06d3762f5ed76838086736da0a Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Wed, 20 Dec 2023 15:26:51 +0100
Subject: [PATCH 06/10] Fix component configuration retry logic if unused
 components exist

---
 src/batou/environment.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/batou/environment.py b/src/batou/environment.py
index 1be15b8d..103376da 100644
--- a/src/batou/environment.py
+++ b/src/batou/environment.py
@@ -528,10 +528,9 @@ def configure(self):
                                 unprepared_components, root
                             )
                         )
-                    if not exceptions:
-                        # configured this component successfully
-                        # we won't have to retry it later
-                        continue
+                    # configured this component successfully
+                    # we won't have to retry it later
+                    continue
                 retry.add(root)
 
             retry.update(self.resources.dirty_dependencies)

From 0c0a8d3dc7d773f1552ba094f9acb5e7661dac20 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Thu, 20 Jun 2024 03:45:01 +0200
Subject: [PATCH 07/10] save stack on component init for better unused error
 message/warning

---
 src/batou/__init__.py               | 14 ++++++++++++--
 src/batou/component.py              | 23 +++++++++++++++++++++++
 src/batou/environment.py            |  5 ++++-
 src/batou/tests/test_environment.py |  8 +++++---
 4 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/src/batou/__init__.py b/src/batou/__init__.py
index 3b8222fc..1d84907e 100644
--- a/src/batou/__init__.py
+++ b/src/batou/__init__.py
@@ -482,16 +482,26 @@ class UnusedComponentsInitialized(ConfigurationError):
     def from_context(cls, components, root):
         self = cls()
         self.unused_components = []
+        self.breadcrumbs = []
         for component in components:
             self.unused_components.append(repr(component.__class__.__name__))
+            self.breadcrumbs.append(component._init_breadcrumbs)
         self.root_name = root.name
         return self
 
     def __str__(self):
-        return f"Unused components: {', '.join(self.unused_components)}"
+        out_str = "Unused components: "
+        for i, component in enumerate(self.unused_components):
+            out_str += f"\n    {component}: {' -> '.join(self.breadcrumbs[i])}"
+        return out_str
 
     def report(self):
-        output.error(f"Unused components: {', '.join(self.unused_components)}")
+        output.error(f"Unused components:")
+        for i, component in enumerate(self.unused_components):
+            output.line(
+                f"    {component}: {' -> '.join(self.breadcrumbs[i])}", red=True
+            )
+        output.tabular("Root", self.root_name, red=True)
 
 
 class UnsatisfiedResources(ConfigurationError):
diff --git a/src/batou/component.py b/src/batou/component.py
index 226c4d48..6df0f52b 100644
--- a/src/batou/component.py
+++ b/src/batou/component.py
@@ -196,6 +196,29 @@ def root(self):
     _prepared = False
 
     def __init__(self, namevar=None, **kw):
+        init_stack = inspect.stack()
+        init_stack.reverse()
+        init_breadcrumbs = []
+        for frame in init_stack:
+            if (
+                "self" in frame.frame.f_locals
+                and isinstance(frame.frame.f_locals["self"], Component)
+                and frame.frame.f_code.co_name == "configure"
+            ):
+                component = frame.frame.f_locals["self"]
+                try:
+                    init_breadcrumbs.append(component._breadcrumb)
+                except AttributeError:
+                    # some ._breadcrumb are broken
+                    breadcrumb = component.__class__.__name__
+                    if component.namevar:
+                        breadcrumb += (
+                            f"({getattr(component, component.namevar, None)})"
+                        )
+                    init_breadcrumbs.append(breadcrumb)
+
+        self._init_breadcrumbs = init_breadcrumbs
+
         Component.instances.append(self)
         self.timer = batou.utils.Timer(self.__class__.__name__)
         # Are any keyword arguments undefined attributes?
diff --git a/src/batou/environment.py b/src/batou/environment.py
index 103376da..2f9cfee3 100644
--- a/src/batou/environment.py
+++ b/src/batou/environment.py
@@ -523,11 +523,14 @@ def configure(self):
                         if not component._prepared:
                             unprepared_components.append(component)
                     if unprepared_components:
-                        exceptions.append(
+                        # TODO: activate in future
+                        unused_exception = (
                             UnusedComponentsInitialized.from_context(
                                 unprepared_components, root
                             )
                         )
+                        # exceptions.append(unused_exception)
+                        output.warn(str(unused_exception))
                     # configured this component successfully
                     # we won't have to retry it later
                     continue
diff --git a/src/batou/tests/test_environment.py b/src/batou/tests/test_environment.py
index bd96c983..8b42e6e2 100644
--- a/src/batou/tests/test_environment.py
+++ b/src/batou/tests/test_environment.py
@@ -334,9 +334,11 @@ def test_resolver_overrides_invalid_address(sample_service):
     assert "thisisinvalid" == errors[0].address
 
 
-def test_unused_components_get_reported(sample_service):
+def test_unused_components_get_reported(sample_service, output):
     e = Environment("test-unused")
     e.load()
-    errors = e.configure()
 
-    assert any(isinstance(e, batou.UnusedComponentsInitialized) for e in errors)
+    output.backend.output = ""
+    e.configure()
+
+    assert "'Unused': BadUnused" in output.backend.output

From 1f916470799628e56d85eb4f9e248ccd654c3639 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Thu, 20 Jun 2024 03:46:17 +0200
Subject: [PATCH 08/10] changelog: report unused Components as warnings

---
 CHANGES.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGES.md b/CHANGES.md
index 15967029..32a9c970 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,7 @@
 -----------------------
 
 - batou migrate now writes .batou.json with a newline at the end as `pre-commit` hooks expect (usually).
+- Unused Components, that is, Components that are initialized, but not used in the deployment, are now reported as warnings.
 
 
 ## 2.5.0b2 (2024-05-15)

From acd98c625b4bb0c1bc717154d2f332b4b0fdfb18 Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Tue, 25 Jun 2024 04:01:00 +0200
Subject: [PATCH 09/10] Add initialization file paths and line numbers to
 UnusedComponentsInitialized error message

---
 src/batou/__init__.py  | 9 +++++++++
 src/batou/component.py | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/src/batou/__init__.py b/src/batou/__init__.py
index 1d84907e..1c849fdd 100644
--- a/src/batou/__init__.py
+++ b/src/batou/__init__.py
@@ -483,9 +483,13 @@ def from_context(cls, components, root):
         self = cls()
         self.unused_components = []
         self.breadcrumbs = []
+        self.init_file_paths = []
+        self.init_line_numbers = []
         for component in components:
             self.unused_components.append(repr(component.__class__.__name__))
             self.breadcrumbs.append(component._init_breadcrumbs)
+            self.init_file_paths.append(component._init_file_path)
+            self.init_line_numbers.append(component._init_line_number)
         self.root_name = root.name
         return self
 
@@ -493,6 +497,7 @@ def __str__(self):
         out_str = "Unused components: "
         for i, component in enumerate(self.unused_components):
             out_str += f"\n    {component}: {' -> '.join(self.breadcrumbs[i])}"
+            out_str += f"\n        initialized in {self.init_file_paths[i]}:{self.init_line_numbers[i]}"
         return out_str
 
     def report(self):
@@ -501,6 +506,10 @@ def report(self):
             output.line(
                 f"    {component}: {' -> '.join(self.breadcrumbs[i])}", red=True
             )
+            output.line(
+                f"        initialized in {self.init_file_paths[i]}:{self.init_line_numbers[i]}",
+                red=True,
+            )
         output.tabular("Root", self.root_name, red=True)
 
 
diff --git a/src/batou/component.py b/src/batou/component.py
index 6df0f52b..73ae7ccb 100644
--- a/src/batou/component.py
+++ b/src/batou/component.py
@@ -199,6 +199,9 @@ def __init__(self, namevar=None, **kw):
         init_stack = inspect.stack()
         init_stack.reverse()
         init_breadcrumbs = []
+        call_site = init_stack[-2]
+        self._init_file_path = call_site.filename
+        self._init_line_number = call_site.lineno
         for frame in init_stack:
             if (
                 "self" in frame.frame.f_locals

From b4b878b360f989110c15ce77cc24add2c7cccf9c Mon Sep 17 00:00:00 2001
From: Eli Kogan-Wang <elikowa@gmail.com>
Date: Tue, 25 Jun 2024 04:11:31 +0200
Subject: [PATCH 10/10] Update UnusedComponentsInitialized error message format

---
 src/batou/__init__.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/batou/__init__.py b/src/batou/__init__.py
index 1c849fdd..62636c97 100644
--- a/src/batou/__init__.py
+++ b/src/batou/__init__.py
@@ -494,14 +494,18 @@ def from_context(cls, components, root):
         return self
 
     def __str__(self):
-        out_str = "Unused components: "
+        out_str = "Some components were initialized but never added to the environment:"
         for i, component in enumerate(self.unused_components):
             out_str += f"\n    {component}: {' -> '.join(self.breadcrumbs[i])}"
             out_str += f"\n        initialized in {self.init_file_paths[i]}:{self.init_line_numbers[i]}"
+        out_str += f"\nRoot: {self.root_name}"
+        out_str += f"\nAdd the components to the environment using `self += component`."
         return out_str
 
     def report(self):
-        output.error(f"Unused components:")
+        output.error(
+            f"Some components were initialized but never added to the environment:"
+        )
         for i, component in enumerate(self.unused_components):
             output.line(
                 f"    {component}: {' -> '.join(self.breadcrumbs[i])}", red=True
@@ -510,6 +514,10 @@ def report(self):
                 f"        initialized in {self.init_file_paths[i]}:{self.init_line_numbers[i]}",
                 red=True,
             )
+        output.line(
+            f"Add the components to the environment using `self += component`.",
+            red=True,
+        )
         output.tabular("Root", self.root_name, red=True)