NodeUtils: export upcall variables to the environment

doc/man/man5/groups.conf.5

@@ -176,6 +176,13 @@ shell commands:
 \fI$SOURCE\fP is replaced by current source name
 .UNINDENT
 .sp
+These variables are also exported as environment variables to the executed
+command, taking precedence over any variables of the same name from the
+calling environment. Shell parameter expansions that are not replaced by the
+library, like \fI${GROUP:\-default}\fP, are then expanded by the shell using the
+same values. The context\-dependent \fI$GROUP\fP and \fI$NODE\fP variables are exported
+with an empty value when they do not apply to the upcall.
+.sp
 Each external command might return a non\-zero return code when the operation
 is not doable. But if the call returns zero, for instance, for a non\-existing
 group, the user will not receive any error when trying to resolve such an

doc/sphinx/config.rst

@@ -504,6 +504,14 @@ replaced before executing shell commands:
 * *$SOURCE* is replaced by the current source name (see a usage example just
   below)
 
+These variables are also exported as environment variables to the executed
+command, taking precedence over any variables of the same name from the
+calling environment. Shell parameter expansions that are not replaced by
+the library, like ``${GROUP:-default}``, are then expanded by the shell
+using the same values. The context-dependent ``$GROUP`` and ``$NODE``
+variables are exported with an empty value when they do not apply to the
+upcall.
+
 Upcall commands are executed with their standard input connected to
 ``/dev/null``, so they must not expect any input on stdin.
 

doc/txt/groups.conf.txt

@@ -140,6 +140,13 @@ shell commands:
 * *$CFGDIR* is replaced by groups.conf highest priority base directory path
 * *$SOURCE* is replaced by current source name
 
+These variables are also exported as environment variables to the executed
+command, taking precedence over any variables of the same name from the
+calling environment. Shell parameter expansions that are not replaced by the
+library, like *${GROUP:-default}*, are then expanded by the shell using the
+same values. The context-dependent *$GROUP* and *$NODE* variables are exported
+with an empty value when they do not apply to the upcall.
+
 Each external command might return a non-zero return code when the operation
 is not doable. But if the call returns zero, for instance, for a non-existing
 group, the user will not receive any error when trying to resolve such an

lib/ClusterShell/NodeUtils.py

@@ -217,8 +217,11 @@ def _upcall_read(self, cmdtpl, args=dict()):
         """
         cmdline = Template(self.upcalls[cmdtpl]).safe_substitute(args)
         self.logger.debug("EXEC '%s'", cmdline)
+        # also export variables so shell expansions like ${GROUP:-x} work
+        env = dict(os.environ, GROUP='', NODE='')
+        env.update((var, str(value)) for var, value in args.items())
         proc = Popen(cmdline, stdin=DEVNULL, stdout=PIPE, shell=True,
-                     cwd=self.cfgdir, universal_newlines=True)
+                     cwd=self.cfgdir, universal_newlines=True, env=env)
         output = proc.communicate()[0].strip()
         self.logger.debug("READ '%s'", output)
         if proc.returncode != 0:

tests/NodeSetGroupTest.py

@@ -1007,6 +1007,38 @@ def testConfigCFGDIR(self):
         self.assertEqual(str(NodeSet("@%s" % tmpgroup, resolver=res)),
                          "example[1-100]")
 
+    def testConfigUpcallEnv(self):
+        """test upcall variables exported in the command environment"""
+        f = make_temp_file(dedent("""
+            [Main]
+            default: local
+
+            [local]
+            map: echo "n-${GROUP:-all}"
+            all: echo "a-${SOURCE:-none}${GROUP:-}"
+            list: basename "${CFGDIR:-/none}"
+            reverse: echo "g-${NODE:-none}"
+            """).encode('ascii'))
+        res = GroupResolverConfig(f.name)
+        # ${VAR:-default} is not replaced by the library: the shell expands
+        # it from the exported environment variables
+        self.assertEqual(str(NodeSet("@foo", resolver=res)), "n-foo")
+        # empty group name: the shell uses the default value
+        self.assertEqual(res.group_nodes(''), ["n-all"])
+        self.assertEqual(res.all_nodes(), ["a-local"])
+        tmpgroup = os.path.basename(os.path.dirname(f.name))
+        self.assertEqual(res.grouplist(), [tmpgroup])
+        self.assertEqual(res.node_groups("node1"), ["g-node1"])
+        # exported variables take precedence over the caller's environment,
+        # and are exported empty to upcalls they do not apply to
+        os.environ['GROUP'] = 'callerenv'
+        try:
+            res = GroupResolverConfig(f.name)
+            self.assertEqual(str(NodeSet("@bar", resolver=res)), "n-bar")
+            self.assertEqual(res.all_nodes(), ["a-local"])
+        finally:
+            del os.environ['GROUP']
+
     def test_fromall_grouplist(self):
         """test NodeSet.fromall() without all upcall"""
         # Group Source that has no all upcall and that can handle special char