docs: update docstrings of passwd, sysctl, systemd and add warning to README

README.md

@@ -3,6 +3,17 @@
 ![Release Libraries](https://github.com/canonical/operator-libs-linux/actions/workflows/release-libs.yaml/badge.svg)
 ![Release to Charmhub](https://github.com/canonical/operator-libs-linux/actions/workflows/release.yaml/badge.svg)
 
+> [!WARNING]
+> The libraries provided by this charm are deprecated and will no longer receive feature updates or bugfixes.
+>
+> Some of the libraries have been migrated to packages in the `charmlibs` monorepo:
+>
+> - [apt](https://documentation.ubuntu.com/charmlibs/reference/charmlibs/apt/)
+> - [passwd](https://documentation.ubuntu.com/charmlibs/reference/charmlibs/passwd/)
+> - [snap](https://documentation.ubuntu.com/charmlibs/reference/charmlibs/snap/)
+> - [sysctl](https://documentation.ubuntu.com/charmlibs/reference/charmlibs/sysctl/)
+> - [systemd](https://documentation.ubuntu.com/charmlibs/reference/charmlibs/systemd/)
+
 ## Description
 
 The `operator-libs-linux` charm provides a set of [charm libraries] which can be used for managing and manipulating Debian packages, [snap packages], system repositories, users and groups, and other operations

lib/charms/operator_libs_linux/v0/passwd.py

@@ -12,7 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Simple library for managing Linux users and groups.
+"""Legacy Charmhub-hosted passwd library, deprecated in favour of ``charmlibs.passwd``.
+
+WARNING: This library is deprecated and will no longer receive feature updates or bugfixes.
+``charmlibs.passwd`` version 1.0 is a bug-for-bug compatible migration of this library.
+Add 'charmlibs-passwd~=1.0' to your charm's dependencies, and remove this Charmhub-hosted library.
+Then replace `from charms.operator_libs_linux.v0 import passwd` with
+`from charmlibs import passwd`.
+Read more:
+- https://documentation.ubuntu.com/charmlibs
+- https://pypi.org/project/charmlibs-passwd
+
+---
+
+Simple library for managing Linux users and groups.
 
 The `passwd` module provides convenience methods and abstractions around users and groups on a
 Linux system, in order to make adding and managing users and groups easy.
@@ -45,7 +58,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 4
+LIBPATCH = 5
 
 
 def user_exists(user: Union[str, int]) -> Optional[pwd.struct_passwd]:

lib/charms/operator_libs_linux/v0/sysctl.py

@@ -12,7 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Handler for the sysctl config.
+"""Legacy Charmhub-hosted sysctl library, deprecated in favour of ``charmlibs.sysctl``.
+
+WARNING: This library is deprecated and will no longer receive feature updates or bugfixes.
+``charmlibs.sysctl`` version 1.0 is a bug-for-bug compatible migration of this library.
+Add 'charmlibs-sysctl~=1.0' to your charm's dependencies, and remove this Charmhub-hosted library.
+Then replace `from charms.operator_libs_linux.v0 import sysctl` with
+`from charmlibs import sysctl`.
+Read more:
+- https://documentation.ubuntu.com/charmlibs
+- https://pypi.org/project/charmlibs-sysctl
+
+---
+
+Handler for the sysctl config.
 
 This library allows your charm to create and configure sysctl options to the machine.
 
@@ -84,7 +97,7 @@ def _on_remove(self, _):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 4
+LIBPATCH = 5
 
 CHARM_FILENAME_PREFIX = "90-juju-"
 SYSCTL_DIRECTORY = Path("/etc/sysctl.d")

lib/charms/operator_libs_linux/v1/systemd.py

@@ -13,7 +13,20 @@
 # limitations under the License.
 
 
-"""Abstractions for stopping, starting and managing system services via systemd.
+"""Legacy Charmhub-hosted systemd library, deprecated in favour of ``charmlibs.systemd``.
+
+WARNING: This library is deprecated and will no longer receive feature updates or bugfixes.
+``charmlibs.systemd`` version 1.0 is a bug-for-bug compatible migration of this library.
+Add 'charmlibs-systemd~=1.0' to your charm's dependencies, and remove this Charmhub-hosted library.
+Then replace `from charms.operator_libs_linux.v0 import systemd` with
+`from charmlibs import systemd`.
+Read more:
+- https://documentation.ubuntu.com/charmlibs
+- https://pypi.org/project/charmlibs-systemd
+
+---
+
+Abstractions for stopping, starting and managing system services via systemd.
 
 This library assumes that your charm is running on a platform that uses systemd. E.g.,
 Centos 7 or later, Ubuntu Xenial (16.04) or later.
@@ -64,7 +77,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 4
+LIBPATCH = 5
 
 
 class SystemdError(Exception):