Provide a fallback copy of telnetlib module for PyNUTClient [#2183]

Signed-off-by: Jim Klimov <[email protected]>

NEWS.adoc

@@ -162,6 +162,10 @@ https://github.com/networkupstools/nut/milestone/11
    as a service, have a help message, pass debug verbosity to launched NUT
    programs...) and add a man page for it. [issue #2432, PR #2446]
 
+ - the `PyNUTClient` module should no longer rely on presence of a `telnetlib`
+   module in the build or execution environment (deprecated in Python 3.11,
+   removed since Python 3.13). [#2183]
+
  - enabled installation of built single-file PDF and HTML (including man page
    renditions) under the configured `docdir`. It seems previously they were
    only built (if requested) but not installed via `make`, unlike the common

configure.ac

@@ -2447,7 +2447,7 @@ if test x"${nut_with_nut_monitor}" != xno ; then
 fi
 
 dnl ${nut_with_pynut}: TODO: arg values to request python 2, 3 or both
-AC_MSG_CHECKING([if we can and should install PyNUT module])
+AC_MSG_CHECKING([if we can and should install PyNUT module (note for warnings from python 3.11 and beyond: we have a fallback nut_telnetlib module just in case)])
 nut_with_pynut_py=""
 nut_with_pynut_py2=""
 nut_with_pynut_py3=""
@@ -2469,6 +2469,15 @@ if test x"${nut_with_pynut}" != xno \
         if ${PYTHON3} -c "import telnetlib" \
         ; then
             nut_with_pynut_py3="yes"
+        else
+            dnl We have a stashed copy from Python 3.10, so
+            dnl this line essentially checks for presence of
+            dnl a usable interpreter implementation compatible
+            dnl with Python 3.x syntax.
+            if (cd script/python/module && ${PYTHON3} -c "import nut_telnetlib as telnetlib") \
+            ; then
+                nut_with_pynut_py3="yes"
+            fi
         fi
     fi
 
@@ -2480,6 +2489,12 @@ if test x"${nut_with_pynut}" != xno \
         if ${PYTHON} -c "import telnetlib" \
         ; then
             nut_with_pynut_py="yes"
+        else
+            dnl See comments above
+            if (cd script/python/module && ${PYTHON} -c "import nut_telnetlib as telnetlib") \
+            ; then
+                nut_with_pynut_py="yes"
+            fi
         fi
     fi
 fi

docs/nut.dict

@@ -1,4 +1,4 @@
-personal_ws-1.1 en 3172 utf-8
+personal_ws-1.1 en 3173 utf-8
 AAC
 AAS
 ABI
@@ -2888,6 +2888,7 @@ tcsetattr
 tcsh
 td
 tdriver
+telnetlib
 tempmax
 tempmin
 termios

scripts/python/Makefile.am

@@ -70,6 +70,7 @@ NUT_MONITOR_COMMON = \
 	app/locale/ru/LC_MESSAGES/NUT-Monitor.mo
 
 PYNUT_COMMON = \
+	module/nut_telnetlib.py \
 	module/README.adoc
 
 # Note: we both distribute and install the generated *.mo translation files

scripts/python/README.adoc

@@ -35,6 +35,21 @@ and protocol support.
 
 For one practical example, you can research `tests/NIT/nit.sh` in NUT sources.
 
+telnetlib
+^^^^^^^^^
+
+Historically, the `PyNUTClient` class relied on `telnetlib` module for socket
+communications with the NUT data server, which was provided as part of Python
+core installation with tested 2.6+ and 3.* versions. The module was, however,
+marked deprecated since Python 3.11 and not provided since 3.13. Due to this,
+as a quick stop-gap solution, NUT sources provide `nut_telnetlib.py` - a copy
+of the module from Python 3.10 installation, and no longer should require its
+presence in the Python deployment.
+
+A better solution would be to find or create a new layer for the constrained
+use-case of NUT client interactions with a data server, which do not need the
+fully fledged Telnet-like capabilities.
+
 app
 ~~~
 

scripts/python/module/Makefile.am

@@ -16,7 +16,7 @@ check-local:
 tox: dist .pypi-tools-tox
 	tox
 
-EXTRA_DIST = tox.ini MANIFEST.in
+EXTRA_DIST = tox.ini MANIFEST.in nut_telnetlib.py
 
 NUT_SOURCE_GITREV_NUMERIC = @NUT_SOURCE_GITREV_NUMERIC@
 PYTHON = @PYTHON@
@@ -64,7 +64,9 @@ upload publish:
 	 esac
 
 # README.txt is also a part of module standard expectations
-.pypi-src: test_nutclient.py.in PyNUT.py.in setup.py.in README.adoc Makefile $(top_srcdir)/LICENSE-GPL3
+# nut_telnetlib.py is not converted from a .in template, it
+# does not even have a shebang line.
+.pypi-src: test_nutclient.py.in PyNUT.py.in setup.py.in nut_telnetlib.py README.adoc Makefile $(top_srcdir)/LICENSE-GPL3
 	@echo "  PYPI  Generate PyPI module source"
 	@rm -rf $(GENERATED_SRC) "$@"
 	@mkdir -p PyNUTClient
@@ -83,6 +85,7 @@ upload publish:
 		sed -e "s,[@]PYTHON[@],@PYTHON@," < "$(srcdir)/$${B}.in" > "PyNUTClient/$${B}" || exit ; \
 		if test -x "$(srcdir)/$${B}.in" ; then chmod +x "PyNUTClient/$${B}"; fi ; \
 	 done ; \
+	 cp -pf "$(srcdir)/nut_telnetlib.py" PyNUTClient/ || exit ; \
 	 cp -pf "$(srcdir)/README.adoc" README.txt || exit ; \
 	 cp -pf "$(top_srcdir)/LICENSE-GPL3" . || exit ; \
 	 echo "from . import PyNUT" > PyNUTClient/__init__.py || exit

scripts/python/module/PyNUT.py.in

@@ -55,8 +55,20 @@
 # 2023-01-18 Jim Klimov <[email protected]> - Version 1.6.0
 #            Added CheckUPSAvailable() method originally by Michal Hlavinka
 #            from 2013-01-07 RedHat/Fedora packaging
+#
+# 2024-07-01 Jim Klimov <[email protected]> - Version 1.7.0
+#            Re-arranged dependency on telnetlib module (deprecated/removed
+#            since Python 3.11/3.13), so we can fall back on a privately
+#            stashed copy until a better solution is developed.
+#
 
-import telnetlib
+try:
+    import telnetlib
+except ModuleNotFoundError:
+    import os
+    if "true" == os.getenv('DEBUG', 'false'):
+        print( "[DEBUG] Fall back to private copy of telnetlib for PyNUTClient\n" )
+    import nut_telnetlib as telnetlib
 
 class PyNUTError( Exception ) :
     """ Base class for custom exceptions """
@@ -73,8 +85,8 @@ class PyNUTClient :
     __timeout     = None
     __srv_handler = None
 
-    __version     = "1.6.0"
-    __release     = "2023-01-18"
+    __version     = "1.7.0"
+    __release     = "2024-07-01"
 
 
     def __init__( self, host="127.0.0.1", port=3493, login=None, password=None, debug=False, timeout=5 ) :