Expand Supervisor to support loading additional scripts before user scripts

In supervised nodes, the Supervisor's NodeConfig$scripts vector adds scripts to
the end of the user-provided scripts (options.scripts_to_load), so they load
_after_ any user-provided ones. This can cause confusing redef pitfalls when
users expect their customizations to run last, as they normally do.

This adds two members in Supervisor::NodeConfig, `addl_base_scripts` and
`addl_user_scripts`, to store scripts to load before and after the user scripts,
respectively. The latter serves the same purpose as the old `scripts` member,
which is still there but deprecated (in scriptland only). It functions as
before, after any scripts added via `addl_user_scripts`.

scripts/base/frameworks/supervisor/api.zeek

@@ -45,8 +45,15 @@ export {
 		## Whether to start the node in bare mode. When left out, the node
 		## inherits the bare-mode status the supervisor itself runs with.
 		bare_mode: bool &optional;
-		## Additional script filenames/paths that the node should load.
+		## Additional script filenames/paths that the node should load
-		scripts: vector of string &default = vector();
+		## after the base scripts, and prior to any user-specified ones.
+		addl_base_scripts: vector of string &default = vector();
+		## Additional script filenames/paths that the node should load
+		## after any user-specified scripts.
+		addl_user_scripts: vector of string &default = vector();
+		## The former name of addl_user_scripts.
+		scripts: vector of string &default = vector()
+		    &deprecated="Remove in 6.1. Use the addl_user_scripts field instead.";
 		## Environment variables to define in the supervised node.
 		env: table[string] of string &default=table();
 		## A cpu/core number to which the node will try to pin itself.

src/supervisor/Supervisor.cc

@@ -1256,6 +1256,22 @@ Supervisor::NodeConfig Supervisor::NodeConfig::FromRecord(const RecordVal* node)
 	if ( bare_mode_val )
 		rval.bare_mode = bare_mode_val->AsBool();
 
+	auto addl_base_scripts_val = node->GetField("addl_base_scripts")->AsVectorVal();
+
+	for ( auto i = 0u; i < addl_base_scripts_val->Size(); ++i )
+		{
+		auto script = addl_base_scripts_val->StringValAt(i)->ToStdString();
+		rval.addl_base_scripts.emplace_back(std::move(script));
+		}
+
+	auto addl_user_scripts_val = node->GetField("addl_user_scripts")->AsVectorVal();
+
+	for ( auto i = 0u; i < addl_user_scripts_val->Size(); ++i )
+		{
+		auto script = addl_user_scripts_val->StringValAt(i)->ToStdString();
+		rval.addl_user_scripts.emplace_back(std::move(script));
+		}
+
 	auto scripts_val = node->GetField("scripts")->AsVectorVal();
 
 	for ( auto i = 0u; i < scripts_val->Size(); ++i )
@@ -1332,6 +1348,16 @@ Supervisor::NodeConfig Supervisor::NodeConfig::FromJSON(std::string_view json)
 	if ( auto it = j.FindMember("bare_mode"); it != j.MemberEnd() )
 		rval.bare_mode = it->value.GetBool();
 
+	auto& addl_base_scripts = j["addl_base_scripts"];
+
+	for ( auto it = addl_base_scripts.Begin(); it != addl_base_scripts.End(); ++it )
+		rval.addl_base_scripts.emplace_back(it->GetString());
+
+	auto& addl_user_scripts = j["addl_user_scripts"];
+
+	for ( auto it = addl_user_scripts.Begin(); it != addl_user_scripts.End(); ++it )
+		rval.addl_user_scripts.emplace_back(it->GetString());
+
 	auto& scripts = j["scripts"];
 
 	for ( auto it = scripts.Begin(); it != scripts.End(); ++it )
@@ -1396,6 +1422,22 @@ RecordValPtr Supervisor::NodeConfig::ToRecord() const
 	if ( bare_mode )
 		rval->AssignField("bare_mode", *bare_mode);
 
+	auto abs_t = rt->GetFieldType<VectorType>("addl_base_scripts");
+	auto addl_base_scripts_val = make_intrusive<VectorVal>(std::move(abs_t));
+
+	for ( const auto& s : addl_base_scripts )
+		addl_base_scripts_val->Assign(addl_base_scripts_val->Size(), make_intrusive<StringVal>(s));
+
+	rval->AssignField("addl_base_scripts", std::move(addl_base_scripts_val));
+
+	auto aus_t = rt->GetFieldType<VectorType>("addl_user_scripts");
+	auto addl_user_scripts_val = make_intrusive<VectorVal>(std::move(aus_t));
+
+	for ( const auto& s : addl_user_scripts )
+		addl_user_scripts_val->Assign(addl_user_scripts_val->Size(), make_intrusive<StringVal>(s));
+
+	rval->AssignField("addl_user_scripts", std::move(addl_user_scripts_val));
+
 	auto st = rt->GetFieldType<VectorType>("scripts");
 	auto scripts_val = make_intrusive<VectorVal>(std::move(st));
 
@@ -1601,8 +1643,11 @@ void SupervisedNode::Init(Options* options) const
 	if ( config.interface )
 		options->interface = *config.interface;
 
-	for ( const auto& s : config.scripts )
+	auto& stl = options->scripts_to_load;
-		options->scripts_to_load.emplace_back(s);
+
+	stl.insert(stl.begin(), config.addl_base_scripts.begin(), config.addl_base_scripts.end());
+	stl.insert(stl.end(), config.addl_user_scripts.begin(), config.addl_user_scripts.end());
+	stl.insert(stl.end(), config.scripts.begin(), config.scripts.end());
 	}
 
 RecordValPtr Supervisor::Status(std::string_view node_name)

src/supervisor/Supervisor.h

@@ -198,9 +198,20 @@ public:
 		 */
 		std::optional<bool> bare_mode;
 		/**
-		 * Additional script filename/paths that the node should load.
+		 * Additional script filenames/paths that the node should load
+		 * after the base scripts, and prior to any user-specified ones.
 		 */
-		std::vector<std::string> scripts;
+		std::vector<std::string> addl_base_scripts;
+		/**
+		 * Additional script filename/paths that the node should load
+		 * after any user-specified scripts.
+		 */
+		std::vector<std::string> addl_user_scripts;
+		/**
+		 * The former name for addl_user_scripts, now deprecated.
+		 */
+		std::vector<std::string> scripts
+			[[deprecated("Remove in v6.1. Use NodeConfig::addl_user_scripts.")]];
 		/**
 		 * Environment variables and values  to define in the node.
 		 */

testing/btest/Baseline/supervisor.config-scripts/zeek.node.out

@@ -1,4 +1,5 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-supervised node zeek_init()
+supervised node zeek_init(), counter at 1
-supervised node loaded qux.zeek
+supervised node loaded addl_user_script.zeek, counter at 2
+supervised node loaded script.zeek, counter at 3
 supervised node zeek_done()

testing/btest/supervisor/config-scripts.zeek

@@ -26,7 +26,9 @@ event zeek_init()
 		supervisor_output_file = open("supervisor.out");
 		print supervisor_output_file, "supervisor zeek_init()";
 		local sn = Supervisor::NodeConfig($name="grault",
-		                                  $scripts=vector("../qux.zeek"));
+		    $addl_base_scripts=vector("../addl_base_script.zeek"),
+		    $addl_user_scripts=vector("../addl_user_script.zeek"),
+		    $scripts=vector("../script.zeek"));
 		local res = Supervisor::create(sn);
 
 		if ( res != "" )
@@ -36,7 +38,15 @@ event zeek_init()
 		{
 		Broker::peer("127.0.0.1", to_port(getenv("BROKER_PORT")));
 		node_output_file = open("node.out");
-		print node_output_file, "supervised node zeek_init()";
+
+@ifdef ( Pre::counter )
+		# Even though this else-block runs only in the supervised node,
+		# it still needs to parse correctly in the Supervisor, so we
+		# need to condition this with availability of the counter (which
+		# only exists in the supervised node).
+		++Pre::counter;
+		print node_output_file, fmt("supervised node zeek_init(), counter at %s", Pre::counter);
+@endif
 		}
 	}
 
@@ -60,11 +70,32 @@ event zeek_done()
 		print supervisor_output_file, "supervisor zeek_done()";
 	}
 
-@TEST-START-FILE qux.zeek
+@TEST-START-FILE addl_base_script.zeek
+
+module Pre;
+
+export {
+	global counter = 0;
+}
+
+@TEST-END-FILE
+
+@TEST-START-FILE addl_user_script.zeek
 
 event zeek_init() &priority=-10
 	{
-	print node_output_file, "supervised node loaded qux.zeek";
+	++Pre::counter;
+	print node_output_file, fmt("supervised node loaded addl_user_script.zeek, counter at %s", Pre::counter);
+	}
+
+@TEST-END-FILE
+
+@TEST-START-FILE script.zeek
+
+event zeek_init() &priority=-20
+	{
+	++Pre::counter;
+	print node_output_file, fmt("supervised node loaded script.zeek, counter at %s", Pre::counter);
 	}
 
 @TEST-END-FILE