modules: use depends-on to autoload module with Lmod on Tcl (#38347)

Update Tcl modulefile template to use the `depends-on` command to
autoload modules if Lmod is the current module tool.

Autoloading modules with `module load` command in Tcl modulefile does
not work well for Lmod at some extend. An attempt to unload then load
designated module is performed each time such command is encountered. It
may lead to a load storm that may not end correctly with large number of
module dependencies.

`depends-on` command should be used for Lmod instead of `module load`,
as it checks if module is already loaded, and does not attempt to reload
this module.

Lua modulefile template already uses `depends_on` command to autoload
dependencies. Thus it is already considered that to use Lmod with Spack,
it must support `depends_on` command (version 7.6+).

Environment Modules copes well with `module load` command to autoload
dependencies (version 3.2+). `depends-on` command is supported starting
version 5.1 (as an alias of `prereq-all` command) which was relased last
year.

This change introduces a test to determine if current module tool that
evaluates modulefile is Lmod. If so, autoload dependencies are defined
with `depends-on` command. Otherwise `module load` command is used.

Test is based on `LMOD_VERSION_MAJOR` environment variable, which is set
by Lmod starting version 5.1.

Fixes #36764

lib/spack/spack/test/modules/tcl.py

@@ -37,6 +37,11 @@ def test_autoload_direct(self, modulefile_content, module_configuration):
         module_configuration("autoload_direct")
         content = modulefile_content(mpileaks_spec_string)
 
+        assert (
+            len([x for x in content if "if {![info exists ::env(LMOD_VERSION_MAJOR)]} {" in x])
+            == 1
+        )
+        assert len([x for x in content if "depends-on " in x]) == 2
         assert len([x for x in content if "module load " in x]) == 2
 
         # dtbuild1 has
@@ -46,6 +51,11 @@ def test_autoload_direct(self, modulefile_content, module_configuration):
         # Just make sure the 'build' dependency is not there
         content = modulefile_content("dtbuild1")
 
+        assert (
+            len([x for x in content if "if {![info exists ::env(LMOD_VERSION_MAJOR)]} {" in x])
+            == 1
+        )
+        assert len([x for x in content if "depends-on " in x]) == 2
         assert len([x for x in content if "module load " in x]) == 2
 
         # The configuration file sets the verbose keyword to False
@@ -58,6 +68,11 @@ def test_autoload_all(self, modulefile_content, module_configuration):
         module_configuration("autoload_all")
         content = modulefile_content(mpileaks_spec_string)
 
+        assert (
+            len([x for x in content if "if {![info exists ::env(LMOD_VERSION_MAJOR)]} {" in x])
+            == 1
+        )
+        assert len([x for x in content if "depends-on " in x]) == 5
         assert len([x for x in content if "module load " in x]) == 5
 
         # dtbuild1 has
@@ -67,6 +82,11 @@ def test_autoload_all(self, modulefile_content, module_configuration):
         # Just make sure the 'build' dependency is not there
         content = modulefile_content("dtbuild1")
 
+        assert (
+            len([x for x in content if "if {![info exists ::env(LMOD_VERSION_MAJOR)]} {" in x])
+            == 1
+        )
+        assert len([x for x in content if "depends-on " in x]) == 2
         assert len([x for x in content if "module load " in x]) == 2
 
     def test_prerequisites_direct(self, modulefile_content, module_configuration):
@@ -103,6 +123,7 @@ def test_alter_environment(self, modulefile_content, module_configuration):
         assert len([x for x in content if x.startswith("prepend-path CMAKE_PREFIX_PATH")]) == 0
         assert len([x for x in content if 'setenv FOO "foo"' in x]) == 0
         assert len([x for x in content if "unsetenv BAR" in x]) == 0
+        assert len([x for x in content if "depends-on foo/bar" in x]) == 1
         assert len([x for x in content if "module load foo/bar" in x]) == 1
         assert len([x for x in content if "setenv LIBDWARF_ROOT" in x]) == 1
 
@@ -434,10 +455,16 @@ def test_autoload_with_constraints(self, modulefile_content, module_configuratio
 
         # Test the mpileaks that should have the autoloaded dependencies
         content = modulefile_content("mpileaks ^mpich2")
+        assert len([x for x in content if "depends-on " in x]) == 2
         assert len([x for x in content if "module load " in x]) == 2
 
         # Test the mpileaks that should NOT have the autoloaded dependencies
         content = modulefile_content("mpileaks ^mpich")
+        assert (
+            len([x for x in content if "if {![info exists ::env(LMOD_VERSION_MAJOR)]} {" in x])
+            == 0
+        )
+        assert len([x for x in content if "depends-on " in x]) == 0
         assert len([x for x in content if "module load " in x]) == 0
 
     def test_modules_no_arch(self, factory, module_configuration):

share/spack/templates/modules/modulefile.tcl

@@ -26,9 +26,17 @@ proc ModulesHelp { } {
 {% endblock %}
 
 {% block autoloads %}
+{% if autoload|length > 0 %}
+if {![info exists ::env(LMOD_VERSION_MAJOR)]} {
 {% for module in autoload %}
-module load {{ module }}
+    module load {{ module }}
 {% endfor %}
+} else {
+{% for module in autoload %}
+    depends-on {{ module }}
+{% endfor %}
+}
+{% endif %}
 {% endblock %}
 {#  #}
 {% block prerequisite %}