allow instance overriding in config

config.lua

@@ -23,6 +23,8 @@ config = {
         ["reddit[.]com"] = {
             -- Specify which frontents should be used
             frontends = { "libreddit", "redlib" }
+            -- This can be used to force and instance on a per site basis, overrides everything else
+            -- force_instance = { "example.com" }
         },
         ["instagram[.]com"] = {
             frontends = { "proxigram" }

main.lua

@@ -39,7 +39,7 @@ client:hook("ready", function()
                     local body = event.stanza:get_child_text("body")
                     if body then
                         for site, services in pairs(config.sites) do
-                            local instance = choose_instance(services.frontends)
+                            local instance = choose_instance(services)
                             for match in string.gmatch(body, string.format("%%s(%s/%%S+)", site)) do
                                 send_reply_link(room, match, site, instance, event)
                             end

utils.lua

@@ -60,12 +60,16 @@ end
 
 -- Choose instance from available services
 function choose_instance(services)
-    -- TODO: make it try all available services before falling back
+    -- TODO: make it try all available frontends before falling back
-    -- Choose a random service
+    -- Return instance if overrided in config
-    local service = services[math.random(#services)]
+    if services.force_instance then 
-    -- Get list of instances for service
+        return services.force_instance
+    end
+    -- Choose a random frontend
+    local frontend = services.frontends[math.random(#services.frontends)]
+    -- Get list of instances for frontend
     for _, service_instance_list in pairs(config.instances) do
-        if service_instance_list.type == service then
+        if service_instance_list.type == frontend then
             -- Based on config choose instance
             if config.random_frontend then
                 -- TODO: cache this?
@@ -99,7 +103,7 @@ function choose_instance(services)
             end
         end
     end
-    return string.format("%s-no-instances-available", service)
+    return string.format("%s-no-instances-available", frontend)
 end
 
 -- Config file