SSinstancing (I need to test this with 2 machines)

code/controllers/configuration/configuration_core.dm

@@ -24,6 +24,8 @@ GLOBAL_DATUM_INIT(configuration, /datum/server_configuration, new())
 	var/datum/configuration_section/gateway_configuration/gateway
 	/// Holder for the general configuration datum
 	var/datum/configuration_section/general_configuration/general
+	/// Holder for the instancing configuration datum
+	var/datum/configuration_section/instancing_configuration/instancing
 	/// Holder for the IPIntel configuration datum
 	var/datum/configuration_section/ipintel_configuration/ipintel
 	/// Holder for the job configuration datum
@@ -79,6 +81,7 @@ GLOBAL_DATUM_INIT(configuration, /datum/server_configuration, new())
 	gamemode = new()
 	gateway = new()
 	general = new()
+	instancing = new()
 	ipintel = new()
 	jobs = new()
 	logging = new()
@@ -98,6 +101,15 @@ GLOBAL_DATUM_INIT(configuration, /datum/server_configuration, new())
 	raw_data = json_decode(raw_json)
 
 	// Now pass through all our stuff
+	load_all_sections()
+
+	// Clear our list to save RAM
+	raw_data = list()
+
+	// And report the load
+	DIRECT_OUTPUT(world.log, "Config loaded in [stop_watch(start)]s")
+
+/datum/server_configuration/proc/load_all_sections()
 	safe_load(admin, "admin_configuration")
 	safe_load(afk, "afk_configuration")
 	safe_load(custom_sprites, "custom_sprites_configuration")
@@ -107,6 +119,7 @@ GLOBAL_DATUM_INIT(configuration, /datum/server_configuration, new())
 	safe_load(gamemode, "gamemode_configuration")
 	safe_load(gateway, "gateway_configuration")
 	safe_load(general, "general_configuration")
+	safe_load(instancing, "instancing_configuration")
 	safe_load(ipintel, "ipintel_configuration")
 	safe_load(jobs, "job_configuration")
 	safe_load(logging, "logging_configuration")
@@ -118,12 +131,6 @@ GLOBAL_DATUM_INIT(configuration, /datum/server_configuration, new())
 	safe_load(url, "url_configuration")
 	safe_load(vote, "voting_configuration")
 
-	// Clear our list to save RAM
-	raw_data = list()
-
-	// And report the load
-	DIRECT_OUTPUT(world.log, "Config loaded in [stop_watch(start)]s")
-
 // Proc to load up instance-specific overrides
 /datum/server_configuration/proc/load_overrides()
 	var/override_file = "config/overrides_[world.port].toml"
@@ -140,25 +147,7 @@ GLOBAL_DATUM_INIT(configuration, /datum/server_configuration, new())
 	// Now safely load our overrides.
 	// Due to the nature of config wrappers, only vars that exist in the config file are applied to the config datums.
 	// This means that an override missing a key doesnt null it out from the main server
-	safe_load(admin, "admin_configuration")
-	safe_load(afk, "afk_configuration")
-	safe_load(custom_sprites, "custom_sprites_configuration")
-	safe_load(database, "database_configuration")
-	safe_load(discord, "discord_configuration")
-	safe_load(event, "event_configuration")
-	safe_load(gamemode, "gamemode_configuration")
-	safe_load(gateway, "gateway_configuration")
-	safe_load(general, "general_configuration")
-	safe_load(ipintel, "ipintel_configuration")
-	safe_load(jobs, "job_configuration")
-	safe_load(logging, "logging_configuration")
-	safe_load(mc, "mc_configuration")
-	safe_load(movement, "movement_configuration")
-	safe_load(overflow, "overflow_configuration")
-	safe_load(ruins, "ruin_configuration")
-	safe_load(system, "system_configuration")
-	safe_load(url, "url_configuration")
-	safe_load(vote, "voting_configuration")
+	load_all_sections()
 
 	// Clear our list to save RAM
 	raw_data = list()

code/controllers/configuration/sections/instancing_configuration.dm

@@ -0,0 +1,20 @@
+/// Config holder for stuff relating to multi-server instances
+/datum/configuration_section/instancing_configuration
+	/// ID of this specific server
+	var/server_id = "paradise_main"
+	/// List of all peer servers
+	var/list/datum/peer_server/peers = list()
+
+/datum/configuration_section/instancing_configuration/load_data(list/data)
+	// Use the load wrappers here. That way the default isnt made 'null' if you comment out the config line
+	CONFIG_LOAD_STR(server_id, data["server_id"])
+
+	if(islist(data["peer_servers"]))
+		for(var/list/server in data["peer_servers"])
+			if(server["server_port"] == world.port) // Skip our own instance
+				continue
+			var/datum/peer_server/PS = new()
+			PS.internal_ip = server["internal_ip"]
+			PS.server_port = server["server_port"]
+			PS.commskey = server["commskey"]
+			peers.Add(PS)

code/controllers/subsystem/instancing.dm

@@ -0,0 +1,63 @@
+SUBSYSTEM_DEF(instancing)
+	name = "Instancing"
+	runlevels = RUNLEVEL_INIT | RUNLEVEL_LOBBY | RUNLEVEL_SETUP | RUNLEVEL_GAME | RUNLEVEL_POSTGAME
+	/// Have we announced startup yet
+	var/startup_announced = FALSE
+	/// Is a check currently running?
+	var/check_running = FALSE
+
+/datum/controller/subsystem/instancing/Initialize(start_timeofday)
+	// Do an initial peer check
+	check_peers()
+	return ..()
+
+/datum/controller/subsystem/instancing/fire(resumed)
+	check_peers()
+
+
+/**
+  * Refreshes all peers on the server
+  *
+  * Called periodically during fire() as well as when a new peer reports itself as online
+  * Only one instance of this proc may run at a time
+  *
+  */
+/datum/controller/subsystem/instancing/proc/check_peers()
+	set waitfor = FALSE // This has sleeps if it cant topic so we dont want to bog things down
+	if(check_running)
+		return
+
+	check_running = TRUE // Dont allow multiple of these
+	// A NOTE TO ANYONE ELSE WHO LOOKS AT THIS
+	// THESE TIMINGS ARE A FUCKING NIGHTMARE AND YOU WILL NEED DEBUG LOGGING TO TEST THEM
+	// DO NOT FUCK WITH THE TIMINGS -aa
+	for(var/datum/peer_server/PS in GLOB.configuration.instancing.peers)
+		// If the server hasnt been discovered and its been more than 5 minutes
+		if((!PS.discovered && PS.last_operation_time + 5 MINUTES > world.time))
+			continue
+
+		if(PS.last_operation_time + 1 MINUTES > world.time)
+			continue // Only run main operations once every minute anyway
+
+		var/peer_response = world.Export("byond://[PS.internal_ip]:[PS.server_port]?server_discovery&key=[PS.commskey]")
+		if(!peer_response)
+			PS.online = FALSE // Peer is offline
+			PS.last_operation_time = world.time
+			continue
+
+		// We got a response
+		PS.discovered = TRUE
+		PS.online = TRUE
+		var/list/peer_data = json_decode(peer_response)
+
+		PS.external_ip = peer_data["external_ip"]
+		PS.server_id = peer_data["server_id"]
+		PS.server_name = peer_data["server_name"]
+		PS.playercount = peer_data["playercount"]
+
+		PS.last_operation_time = world.time
+
+	check_running = FALSE
+
+/datum/controller/subsystem/instancing/proc/message_all_peers(include_offline = FALSE)
+	return